WO2016104448A1 - Method for mining water-soluble natural gas - Google Patents
Method for mining water-soluble natural gas Download PDFInfo
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- WO2016104448A1 WO2016104448A1 PCT/JP2015/085714 JP2015085714W WO2016104448A1 WO 2016104448 A1 WO2016104448 A1 WO 2016104448A1 JP 2015085714 W JP2015085714 W JP 2015085714W WO 2016104448 A1 WO2016104448 A1 WO 2016104448A1
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- gas
- water
- layer
- methane
- mudstone
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 424
- 239000003345 natural gas Substances 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 42
- 238000005065 mining Methods 0.000 title claims abstract description 39
- 239000007789 gas Substances 0.000 claims abstract description 223
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 184
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 92
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 90
- 238000002347 injection Methods 0.000 claims abstract description 60
- 239000007924 injection Substances 0.000 claims abstract description 60
- 238000004519 manufacturing process Methods 0.000 claims abstract description 60
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 59
- 239000008398 formation water Substances 0.000 claims description 55
- 150000003839 salts Chemical class 0.000 claims description 24
- 230000008569 process Effects 0.000 claims description 5
- 239000004575 stone Substances 0.000 abstract 4
- 239000012071 phase Substances 0.000 description 17
- 229910052500 inorganic mineral Inorganic materials 0.000 description 16
- 239000011707 mineral Substances 0.000 description 16
- 239000002245 particle Substances 0.000 description 16
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 14
- 238000003795 desorption Methods 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 8
- 238000000926 separation method Methods 0.000 description 8
- 238000006467 substitution reaction Methods 0.000 description 7
- 239000012267 brine Substances 0.000 description 5
- NMJORVOYSJLJGU-UHFFFAOYSA-N methane clathrate Chemical compound C.C.C.C.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O NMJORVOYSJLJGU-UHFFFAOYSA-N 0.000 description 5
- 238000011084 recovery Methods 0.000 description 5
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 5
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 4
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 230000009471 action Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000011630 iodine Substances 0.000 description 4
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
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- 241000203069 Archaea Species 0.000 description 1
- 241000894006 Bacteria Species 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 229920002907 Guar gum Polymers 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
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- LFYJSSARVMHQJB-QIXNEVBVSA-N bakuchiol Chemical compound CC(C)=CCC[C@@](C)(C=C)\C=C\C1=CC=C(O)C=C1 LFYJSSARVMHQJB-QIXNEVBVSA-N 0.000 description 1
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- 230000005764 inhibitory process Effects 0.000 description 1
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- -1 sodium chloride Chemical class 0.000 description 1
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Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/2605—Methods for stimulating production by forming crevices or fractures using gas or liquefied gas
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
Definitions
- the present invention relates to a method for mining natural gas from a water-soluble natural gas field.
- Japan in addition to methane hydrate, water-soluble natural gas is mined.
- the area where water-soluble natural gas is produced exists in various parts of Japan, but in the southern Kanto area, especially in Chiba Prefecture, there is Japan's largest water-soluble natural gas field called the South Kanto Gas Field.
- Water-soluble natural gas is thought to exist in a state where methane gas, which is produced when bacteria decompose biological organisms such as animals and plants deposited on the seabed with sand and mud in ancient times, is dissolved in the formation water. (See Non-Patent Document 1).
- methane gas which is produced when bacteria decompose biological organisms such as animals and plants deposited on the seabed with sand and mud in ancient times, is dissolved in the formation water.
- a sandstone layer and a mudstone layer are formed adjacent to each other (sand mud alternate layer), and the above-mentioned methane gas is dissolved in the sandstone layer and the mudstone layer. Contains water.
- the water-soluble natural gas of the Minami Kanto Gas Field is dissolved in formation water containing salt, such as sodium chloride, called Kansui.
- salt such as sodium chloride
- submerged water contained in the sandstone layer is provided in the production well. Pumped up using a pump. The flooded water pumped up to the ground releases methane gas by aeration under atmospheric pressure.
- carbon dioxide (CO 2 ) or carbon dioxide-dissolved water is injected into the sandstone layer, which is an aquifer, separately from the production well.
- the ratio of the amount of methane gas produced in a water-soluble natural gas field to the amount of water matches the saturated gas / water ratio with respect to the pressure and temperature of the sandstone layer containing methane gas. From this, it is considered that most of the natural gas produced in the water-soluble natural gas field is methane gas contained in the brine collected from the sandstone formation which is an aquifer and not methane gas contained in the mudstone formation. On the other hand, in some areas of the South Kanto gas field, methane gas exceeding the saturated gas water ratio is produced, and so the free gas in the mudstone layer may flow into the sandstone layer, so-called mudstone There is a theory. As a result of the experimental study to verify this mudstone theory, it is considered that the behavior in which the production gas water ratio increases is caused by the supply of free methane gas from mudstone (Non-patent Document 3).
- the mudstone layer is composed of soft mudstone, and the permeability of methane is 0.002 to 0.008 md, which is very small compared to sandstone, but the porosity is 30 to 40%, which is the same value as the sandstone layer.
- the voids in the mudstone layer are thought to contain formation water in which methane gas has dissolved.
- the mudstone layer contains various mineral particles, and it is thought that a large amount of methane molecules are adsorbed around these mineral particles. Thus, it is considered that the methane present in the mudstone layer moves to the sandstone layer and dissolves in the brine when the adsorption amount to the mineral particles and the dissolution amount in the water filling the voids become saturated.
- the amount of methane in the mudstone layer is quoted from the data of Non-Patent Document 4.
- the adsorption amount per cubic meter of mudstone layer is 10 cubic meters, and the dissolved amount in water filling the voids.
- the total amount of adsorbed methane and dissolved methane present in the mudstone layer is estimated to exceed the amount of dissolved methane present per 0.8 meter of sandstone layer.
- the ratio of the amount of methane gas produced in the water-soluble natural gas field to the amount of water matches the saturated gas / water ratio with respect to the pressure and temperature of the sandstone layer containing methane gas. From this, it is considered that most of the natural gas produced in the water-soluble natural gas field is methane gas contained in the brine collected from the sandstone formation which is an aquifer and not methane gas contained in the mudstone formation.
- the present invention has been made in view of the above circumstances, and in a water-soluble natural gas field, there is provided a water-soluble natural gas mining method that enables mining of methane gas contained in a mudstone layer as well as from a sandstone layer. The purpose is to provide.
- the present invention is a method for mining water-soluble natural gas from a gas field having a geological structure in which a sandstone layer and a mudstone layer are adjacent to each other vertically, Substituting methane in the mudstone layer with the gas by injecting gas into the gas field through an injection well drilled in the gas field; Collecting the methane substituted for the gas through a production well excavated in the gas field.
- the first aspect of the water-soluble natural gas mining method of the present invention further includes a step of injecting water into the sandstone layer through the injection well following the injection of the gas.
- the gas is injected into the sandstone layer from the injection well, and is injected between the formation water in the sandstone layer and the water injected into the sandstone layer prior to the water.
- a cell of the generated gas is defined, and by maintaining the pressurization of the water against the sandstone layer, the cell moves from the injection well toward the production well, and in the process of moving the cell, The methane in the mudstone layer is replaced with the gas in the cell, and the methane that has moved to the gas phase in the cell is collected through the production well together with the formation water.
- the gas injection and the water injection into the sandstone layer may be performed alternately.
- a plurality of the cells are defined in the sandstone layer.
- the said several cell moves toward the said production well from the said injection well by maintaining the pressurization of the said gas or the said water with respect to the said sandstone layer.
- the water to be pressed into the sandstone layer is preferably water containing salt (for example, brine, seawater).
- the gas may be injected into the mudstone layer from the injection well.
- the second aspect of the water-soluble natural gas mining method of the present invention further includes a step of generating a crack in the mudstone layer.
- a step of generating a crack in the mudstone layer by injecting the gas from the injection well into the crack, methane in the mudstone layer is collected by being replaced with the gas injected into the crack.
- the third aspect of the water-soluble natural gas mining method of the present invention further includes a step of excavating a horizontal pit in the mudstone layer in a direction in which the mudstone layer spreads.
- the gas is injected into the horizontal shaft, the methane in the mudstone layer is replaced with the gas pressed into the horizontal shaft, and the methane replaced with the gas is the sandstone. Move to the bed and be collected through the production well.
- the gas preferably contains carbon dioxide.
- the injection well may be used as the production well. In that case, the gas injected into the crack is recovered through the injection well.
- the present invention it is possible to mine not only the sandstone layer but also methane gas contained in the mudstone layer. Thereby, the recoverable reserves of natural gas in the water-soluble natural gas field can be increased, and underground resources can be effectively utilized. Moreover, carbon dioxide gas is adopted as a gas to be pressed into the mudstone layer, and the global warming can be prevented and suppressed by performing an underground reduction of the carbon dioxide gas.
- FIG. 1 A water-soluble natural gas field according to the first embodiment of the present invention is shown in FIG. Under the gas field, a layer (sand mud alternate layer) in which sandstone layers 1 and mudstone layers 2a and 2b (2) are alternately adjacent to each other is formed.
- the voids in the sandstone layer 1 which is an aquifer contain formation water in which methane gas is dissolved.
- the mudstone layer 2 has voids similar to sandstone, and the voids also contain formation water in which methane gas has dissolved.
- the mudstone layer 2 contains various mineral particles, and a large amount of methane molecules are adsorbed around the mineral particles. As described above, it is estimated that the mudstone layer 2 contains methane gas that exceeds the amount existing in the sandstone layer 1.
- an injection well 10 for injecting carbon dioxide into the formation where methane gas exists is drilled to a depth that reaches the sandstone layer 1 through the upper mudstone layer 2a.
- a production well 20 for pumping formation water containing methane gas from a formation where methane gas exists is excavated to a depth reaching the sandstone layer 1 like the injection well 10.
- the injection well 10 and the production well 20 are placed with an appropriate distance between the region where the presence of formation water including methane gas can be expected. Both the injection well 10 and the production well 20 reach the mudstone layer 2b deeper than the sandstone layer 1.
- a carbon dioxide supply device 13 and a salt water supply device 14 are connected to the upper end of the casing 11 exposed to the ground of the injection well 10 through a valve 12.
- the carbon dioxide supply device 13 includes a compressor, compresses the carbon dioxide supplied from the carbon dioxide supply source 16 to 100 atm or more using the compressor, and press-fits into the sandstone layer 1 through the casing 11.
- a perforation 11a is formed in the pipe wall of the casing 11 at a depth level of the sandstone layer 1, and carbon dioxide is supplied to the sandstone layer 1 through the perforation 11a.
- the carbon dioxide gas is not limited to a high-purity carbon dioxide gas in which the main composition excluding inevitable impurities is composed of only CO 2, but contains a relatively high concentration of CO 2 as the main composition excluding inevitable impurities.
- the origin of the carbon dioxide gas to be used here is assumed to be a facility that consumes a large amount of CO 2 by consuming so-called fossil fuel in the operation process such as a power plant or factory.
- the carbon dioxide gas changes from a gas phase to a liquid phase or a supercritical state when supplied to the depth level of the sandstone layer 1. That is, it is considered that CO 2 supplied underground is not limited to the gas phase but includes a liquid phase or a supercritical phase. Although this point is the same for underground methane, in the following description, it will be expressed as “carbon dioxide gas” and “methane gas” for convenience.
- the salt water supply device 14 includes a pressurizing pump, and pressurizes water supplied from a salt water source 17 to a level equivalent to the pressure applied to the carbon dioxide gas using the pump.
- the sandstone layer 1 is supplied through the casing 11.
- the injection of carbon dioxide by the carbon dioxide supply device 13 and the injection of salt water by the salt water supply device 14 are selectively performed via the valve 12.
- the gas to be pressed into the sandstone layer 1 using the carbon dioxide supply device 13 may be nitrogen gas or argon gas separated and recovered from air or the like instead of the carbon dioxide gas.
- nitrogen gas or argon gas injected into the sandstone layer 1 cannot be expected to dissolve in water, and flows to the production well side in a state mixed with methane gas released from water.
- salt water to be pressed into the sandstone layer 1 using the salt water supply device 14 the brine pumped from the underground through the production well 20 may be reused, or seawater may be used in the coastal area.
- a separator 23 for separating formation water and methane gas is connected to the upper end of the casing 21 exposed on the ground of the production well 20 through a valve 22.
- the separation device 23 is connected to a natural gas production plant 30 via a pipeline.
- the formation water from which the methane gas has been separated by the separation device 23 is drained into the formation water recovery pond 31.
- the collected formation water may be reused as underground injection water as described above.
- the separation device 23 may be connected to an iodine production plant (not shown) instead of the recovery pond 31.
- the water-soluble natural gas is mined as follows. First, the valve 12 is switched to the carbon dioxide supply device 13, and carbon dioxide is injected into the sandstone layer 1 through the perforations 11 a formed in the casing 11 of the injection well 10. When a predetermined amount of carbon dioxide gas is pressed into the sandstone layer 1, the valve 12 is switched to the saltwater supply device 14, and the saltwater W is pressed into the sandstone layer 1 through the perforations 11 a of the casing 11.
- cell C 1 is defined in.
- the molecules of carbon dioxide dissolved in the formation water in the mudstone layers 2a and 2b are replaced with the molecules of methane gas adsorbed on the mineral particles P contained in the mudstone layers 2a and 2b. Molecules of free methane gas from the mineral particles P by replacement of the carbon dioxide gas molecules move Doroiwaso 2a, 2b to the cell C 1. Furthermore, not only the methane gas dissolved in the formation water as described above and the methane gas released from the mineral particles P, but also methane gas existing in various states in the mudstone layers 2a, 2b is replaced with carbon dioxide gas, Doroiwaso 2a, moves from 2b to the cell C 1.
- the change in the methane desorption rate when the carbon dioxide concentration in the gas phase is increased, a gradual rise curve is drawn until the carbon dioxide concentration is close to 80 mol%, and when the concentration exceeds 80 mol%, the increase becomes more prominent. The tendency to become can be read. In addition, it can be confirmed that the relationship between the carbon dioxide concentration and the methane desorption rate hardly depends on the pressure of the mixed gas supplied to the closed space.
- the methane desorption rate in this experiment is the ratio of the desorption amount to the adsorption amount of pure methane on dry mudstone.
- the methane desorption rate can be directly replaced with the methane recovery rate. For example, when the mixed gas of 20 mol% of methane and 80 mol% of carbon dioxide gas contacts mudstone, the final recovery rate of methane is about 60%.
- a plurality of carbon dioxide cells C 2 to C n are defined in the sandstone layer 1 across the region filled with the salt water W. . Also in the cell C 2 ⁇ C n, said cell C 1 in the same manner as in mudstone layers 2a, occurs substitution of carbon dioxide and methane with the 2b, methane became free state is Doroiwaso 2a, 2b to Move to each cell.
- the carbon dioxide gas or salt water is continuously maintained in the sandstone layer 1.
- the formation water flows toward the production well 20.
- formation water containing methane gas can be pumped from the sandstone layer 1 by the action of the formation water in the sandstone layer 1.
- the cells C 1 to C n of the carbon dioxide gas in the sandstone layer 1 move from the injection well 10 to the production well 20 with the flow of the formation water in the sandstone layer 1.
- the interfaces between the cells C 1 to C n and the mudstone layers 2a and 2b are sequentially updated as the cells C 1 to C n move, the carbon dioxide gas and methane generated between each cell and the mudstone layers 2a and 2b. the substitution of not lose the activity, concentration of methane is accelerated in the gas phase results to the cell C 1.
- the composition of the gas phase in the cells C 1 to C n increases the methane concentration as it approaches the production well 20, and conversely decreases the carbon dioxide concentration.
- Perforations 21a are formed in the pipe wall of the casing 21 at the depth level of the sandstone layer 1, and when the cell reaches the production well 20, methane gas and other water-soluble natural gas concentrated along with the movement of the cell are perforated. It flows into the casing 21 through 21 a and is collected from the sandstone layer 1. The collected gas is transported to the production plant 30 together with the methane gas separated from the formation water by the separation device 23, subjected to desired processing, and supplied for commercial supply and demand.
- the recoverable reserves of natural gas in the water-soluble natural gas field can be increased, and underground resources can be effectively utilized.
- global warming is reduced by reducing carbon dioxide (carbon dioxide), which is discharged into the atmosphere as a result of consumption of fossil fuels and is one of the causes of global warming. Prevention of inhibition can be achieved.
- a known thickener such as polyacrylamide or guar gum may be added to the aqueous phase.
- a thickener such as polyacrylamide or guar gum
- the cells of the carbon dioxide gas and the sandstone layers 2a, 2b partitioned into the salt water Increases contact time with.
- the replacement of carbon dioxide with methane occurs actively as the contact time between the cell and the sandstone layer increases, so an increase in methane gas production can be expected.
- the addition of the thickener means that the carbon dioxide gas is not intended to proceed in the sandstone layer 1, that is, the carbon dioxide gas is pushed through the salt water in the sandstone layer 1 and is no longer used for cell definition. Also prevent.
- the mudstone layer 2a is fractured in the direction in which the layer spreads (fracturing).
- the high-pressure carbon dioxide gas supplied to the fissure 40 is dissolved in the formation water contained in the mudstone layer 2a, and the carbon dioxide molecules are dissolved in the formation water of the mudstone layer 2a from the beginning according to Henry's law of partial pressure.
- methane gas (CH 4 ) molecules Methane gas molecules separated from the formation water by substitution with carbon dioxide gas molecules move from the mudstone layer 2a to the voids of the cracks 40. Further, carbon dioxide gas molecules dissolved in the formation water in the mudstone layer 2a are replaced with methane gas molecules adsorbed on the mineral particles P contained in the mudstone layer 2a. Methane gas molecules liberated from the mineral particles P by substitution with carbon dioxide gas molecules also move from the mudstone layer 2a to the gaps of the cracks 40. When the methane gas moves from the mudstone layer 2a to the gap of the crack 40 by the replacement with the carbon dioxide gas, the gas phase in the crack 40 increases the concentration of methane. On the other hand, since carbon dioxide dissolves in the formation water contained in the mudstone layer 2a, the gas phase in the crack 40 reduces the concentration of carbon dioxide, so the gas phase in the crack 40 is relatively concentrated in methane. Will increase.
- the gas pressure in the crack 40 becomes higher than the gas pressure in the sandstone layer 1. Therefore, the methane gas accumulated in the crack 40 moves from the mudstone layer 2 a to the sandstone layer 1. Moreover, not only the methane gas dissolved in the formation water as described above and the methane gas liberated from the mineral particles P, but also the methane gas existing in various states in the mudstone layer 2a is also generated from the mudstone layer 2a. Move to the gap.
- the methane gas that has moved to the sandstone layer 1 moves in the sandstone layer 1 together with the formation water as it is pumped in the production well 20, reaches the production well 20, and is collected from the sandstone layer 1 together with the formation water through the casing 21.
- the collected gas is transported to the production plant 30 together with the methane gas separated from the formation water by the separation device 23, subjected to desired processing, and supplied for commercial supply and demand.
- the second embodiment of the mining method of the present invention not only the sandstone layer 1 but also the methane gas contained in the mudstone layer 2a can be mined. Thereby, the recoverable reserves of natural gas in the water-soluble natural gas field can be increased, and underground resources can be effectively utilized.
- the crack 40 is generated in the mudstone layer 2a shallower than the sandstone layer 1, but a crack may be generated in the mudstone layer 2b deeper than the sandstone layer 1, or both mudstones. You may make a crack in the layers 2a and 2b.
- the injection well 10 should be excavated to a depth that penetrates the sandstone layer 1 and reaches the lower mudstone layer 2b.
- the gas in the crack 40 flows and sweeps the sandstone layer 1, it is expected that the progress is less directional and diffuses in all directions. Therefore, in consideration of such a case, a plurality of production wells 20 may be excavated so as to surround the injection well 10, and natural gas may be mined in each production well 20.
- the methane gas contained in the mudstone layer 2a can be mined alone, not together with the methane gas contained in the sandstone layer 1.
- the sandstone layer 1 is an underground gas field unsuitable for mining water-soluble natural gas
- natural gas is extracted from the mudstone layer 2. It can be mined and underground resources can be used effectively.
- the injection well serves as the production well, it can be suitably used for a relatively small natural gas field.
- FIG. 6 a horizontal well is excavated at the lower end of the vertical shaft reaching the mudstone layer 2 a to form the injection well 210.
- a large number of perforations 41a are formed in the casing 41 inserted through the horizontal pit.
- carbon dioxide is injected into the mudstone layer 2a through the perforations 41a of the casing 41 of the injection well 210, the carbon dioxide gas is supplied to the sandstone layer 1 through the mudstone layer 2a.
- the horizontal pit is excavated only in the upper mudstone layer 2a, but it may be excavated in the lower mudstone layer 2b, or may be excavated in both.
- the carbon dioxide gas molecules dissolved in the formation water in the mudstone layer 2a are replaced with the methane gas molecules adsorbed on the mineral particles P contained in the mudstone layer 2a and are released from the mineral particles P.
- the gas pressure in the mudstone layer 2a becomes higher than the gas pressure in the sandstone layer 1 by the injection of carbon dioxide. For this reason, the methane gas that is in a free state by replacing with carbon dioxide gas moves from the mudstone layer 2a to the sandstone layer 1 due to the pressure difference between the mudstone layer 2a and the sandstone layer 1.
- Methane gas molecules liberated from the mineral particles P also move from the mudstone layer 2a to the sandstone layer 1 due to a pressure difference between the mudstone layer 2a and the sandstone layer 1. Furthermore, not only the methane gas dissolved in the formation water as described above and the methane gas liberated from the mineral particles P, but also the methane gas existing in various states in the mudstone layer 2a is also the mudstone layer 2a and the sandstone layer 1 It moves from the mudstone layer 2a to the sandstone layer 1 due to the pressure difference.
- the high-concentration methane gas in the sandstone layer 1 moves in the sandstone layer 1 together with the formation water as it is pumped in the production well 20, reaches the production well 20, and is collected from the sandstone layer 1 together with the formation water through the casing 21. .
- the collected gas is transported to the production plant 30 together with the methane gas separated from the formation water by the separation device 23, subjected to desired processing, and supplied for commercial supply and demand.
- the fourth embodiment of the mining method of the present invention not only the sandstone layer 1 but also the methane gas contained in the mudstone layer 2a is mined as in the second embodiment. Is possible. Thereby, the recoverable reserves of natural gas in the water-soluble natural gas field can be increased, and underground resources can be effectively utilized.
- the present invention relates to a method for mining water-soluble natural gas from a gas field having a geological structure in which a mudstone layer and a sandstone layer are adjacent to each other vertically, and is particularly included in a mudstone layer that has not been proposed so far.
- the present invention relates to a method that enables mining of methane gas. ADVANTAGE OF THE INVENTION According to this invention, the recoverable reserve of the natural gas in a water-soluble natural gas field can be increased, and an underground resource can be utilized effectively.
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Abstract
The present invention provides a method for mining water-soluble natural gas, whereby it is possible to mine not only methane gas from a sandstone layer but also methane gas that is included in a mud-stone layer in a water-soluble natural gas field. Specifically, the present invention comprises performing a step for injecting a gas into a mud-stone layer (2) through an injection well (10) drilled in a water-soluble natural gas field having a stratum structure in which a sandstone layer (1) and a mud-stone layer (2) are adjacent to each other one above the other, and thereby replacing methane in the mud-stone layer (2) with carbon dioxide gas, and a step for collecting the methane replaced with carbon dioxide gas through a production well (20) drilled in the gas field.
Description
本発明は、水溶性天然ガス田から天然ガスを採掘する方法に関する。
本願は、2014年12月22日に日本に出願された特願2014-259427号に対して優先権を主張し、その内容をここに援用する。 The present invention relates to a method for mining natural gas from a water-soluble natural gas field.
This application claims priority to Japanese Patent Application No. 2014-259427 filed in Japan on December 22, 2014, the contents of which are incorporated herein by reference.
本願は、2014年12月22日に日本に出願された特願2014-259427号に対して優先権を主張し、その内容をここに援用する。 The present invention relates to a method for mining natural gas from a water-soluble natural gas field.
This application claims priority to Japanese Patent Application No. 2014-259427 filed in Japan on December 22, 2014, the contents of which are incorporated herein by reference.
近年、シェールガスやメタンハイドレートなどの非在来型天然ガス資源が注目を集めている。米国では、頁岩に含まれるシェールガスの採掘技術が確立されて飛躍的に生産量が増加し、世界のエネルギー事情を大きく変化させるムーブメント(いわゆるシェールガス革命)が起こっている。日本でも、海底に氷に似た状態で保存されているメタン、すなわちメタンハイドレートの試掘が成功し、商業的な開発に向けて大きな期待が寄せられている。
In recent years, unconventional natural gas resources such as shale gas and methane hydrate have attracted attention. In the United States, shale gas mining technology contained in shale has been established and production has increased dramatically, and a movement (so-called shale gas revolution) has occurred that greatly changes the world's energy situation. In Japan as well, methane hydrate stored on the sea floor in a state similar to ice, that is, methane hydrate, has been successfully tested, and there are great expectations for commercial development.
日本では、メタンハイドレートの他にも、水溶性天然ガスの採掘が行なわれている。水溶性天然ガスの産出する地域は日本各地に存在するが、中でも千葉県を中心とした南関東一帯には、南関東ガス田と呼ばれる日本最大の水溶性天然ガス田が存在する。
In Japan, in addition to methane hydrate, water-soluble natural gas is mined. The area where water-soluble natural gas is produced exists in various parts of Japan, but in the southern Kanto area, especially in Chiba Prefecture, there is Japan's largest water-soluble natural gas field called the South Kanto Gas Field.
水溶性天然ガスは、太古の昔に砂や泥と一緒に海底に堆積した動植物等の生体有機物をバクテリアが分解するときにできるメタンガスが、地層水に溶け込んだ状態で存在するものと考えられている(非特許文献1を参照)。水溶性天然ガス田には、砂岩層と泥岩層とが相互に隣り合って存在する層(砂泥互層)が形成されており、その砂岩層及び泥岩層には、上記のメタンガスが溶け込んだ地層水が含まれている。
Water-soluble natural gas is thought to exist in a state where methane gas, which is produced when bacteria decompose biological organisms such as animals and plants deposited on the seabed with sand and mud in ancient times, is dissolved in the formation water. (See Non-Patent Document 1). In the water-soluble natural gas field, a sandstone layer and a mudstone layer are formed adjacent to each other (sand mud alternate layer), and the above-mentioned methane gas is dissolved in the sandstone layer and the mudstone layer. Contains water.
南関東ガス田の水溶性天然ガスは、鹹水(かんすい)と呼ばれる塩化ナトリウムなどの塩分を含む地層水に溶け込んでおり、南関東ガス田では、砂岩層に含まれる鹹水を生産井に設けた水中ポンプなどを使って汲み上げている。地上に汲み上げられた鹹水は大気圧下に曝気することでメタンガスを放出する。
鹹水を採取するにあたっては、水中ポンプの作用に加えて、帯水層である砂岩層に、生産井とは別に設けた圧入井を通じて炭酸ガス(CO2)又は炭酸ガス溶解水を圧入して砂岩層に含まれる鹹水を加圧し、生産井を通じて砂岩層から水溶性天然ガスを含む地層水を汲み上げる方法が提案されている(例えば、特許文献1及び非特許文献2を参照)。
ちなみにこの地域で採取される鹹水には通常の海水の約2000倍という高濃度のヨウ素が含まれており、商業的に開発されて国内のヨウ素生産量の約80%を占めている。 The water-soluble natural gas of the Minami Kanto Gas Field is dissolved in formation water containing salt, such as sodium chloride, called Kansui. In the Minami Kanto Gas Field, submerged water contained in the sandstone layer is provided in the production well. Pumped up using a pump. The flooded water pumped up to the ground releases methane gas by aeration under atmospheric pressure.
In collecting the dredged water, in addition to the action of the submersible pump, carbon dioxide (CO 2 ) or carbon dioxide-dissolved water is injected into the sandstone layer, which is an aquifer, separately from the production well. There has been proposed a method of pressurizing submerged water contained in a formation and pumping formation water containing water-soluble natural gas from a sandstone formation through a production well (see, for example,Patent Document 1 and Non-Patent Document 2).
By the way, the dredged water collected in this region contains iodine at a concentration as high as about 2000 times that of normal seawater, and it is developed commercially and accounts for about 80% of the domestic iodine production.
鹹水を採取するにあたっては、水中ポンプの作用に加えて、帯水層である砂岩層に、生産井とは別に設けた圧入井を通じて炭酸ガス(CO2)又は炭酸ガス溶解水を圧入して砂岩層に含まれる鹹水を加圧し、生産井を通じて砂岩層から水溶性天然ガスを含む地層水を汲み上げる方法が提案されている(例えば、特許文献1及び非特許文献2を参照)。
ちなみにこの地域で採取される鹹水には通常の海水の約2000倍という高濃度のヨウ素が含まれており、商業的に開発されて国内のヨウ素生産量の約80%を占めている。 The water-soluble natural gas of the Minami Kanto Gas Field is dissolved in formation water containing salt, such as sodium chloride, called Kansui. In the Minami Kanto Gas Field, submerged water contained in the sandstone layer is provided in the production well. Pumped up using a pump. The flooded water pumped up to the ground releases methane gas by aeration under atmospheric pressure.
In collecting the dredged water, in addition to the action of the submersible pump, carbon dioxide (CO 2 ) or carbon dioxide-dissolved water is injected into the sandstone layer, which is an aquifer, separately from the production well. There has been proposed a method of pressurizing submerged water contained in a formation and pumping formation water containing water-soluble natural gas from a sandstone formation through a production well (see, for example,
By the way, the dredged water collected in this region contains iodine at a concentration as high as about 2000 times that of normal seawater, and it is developed commercially and accounts for about 80% of the domestic iodine production.
水溶性天然ガス田において生産されるメタンガスの量と水量との比率は、メタンガスを含む砂岩層の圧力、温度に対する飽和ガス/水比に符合する。このことから、水溶性天然ガス田において生産される天然ガスはほとんどが帯水層である砂岩層から回収された鹹水に含まれるメタンガスであり、泥岩層に含まれるメタンガスではないと考えられる。
一方、南関東ガス田の一部地域では、飽和ガス水比を超えたメタンガスが生産されており、このことから泥岩層内の遊離ガスが砂岩層内に流動するのではないかという、いわゆる泥岩説が唱えられている。この泥岩説を検証する実験研究の結果、生産ガス水比が大きくなる挙動は泥岩から遊離メタンガスが供給されることによって生じていると考察されている(非特許文献3)。 The ratio of the amount of methane gas produced in a water-soluble natural gas field to the amount of water matches the saturated gas / water ratio with respect to the pressure and temperature of the sandstone layer containing methane gas. From this, it is considered that most of the natural gas produced in the water-soluble natural gas field is methane gas contained in the brine collected from the sandstone formation which is an aquifer and not methane gas contained in the mudstone formation.
On the other hand, in some areas of the South Kanto gas field, methane gas exceeding the saturated gas water ratio is produced, and so the free gas in the mudstone layer may flow into the sandstone layer, so-called mudstone There is a theory. As a result of the experimental study to verify this mudstone theory, it is considered that the behavior in which the production gas water ratio increases is caused by the supply of free methane gas from mudstone (Non-patent Document 3).
一方、南関東ガス田の一部地域では、飽和ガス水比を超えたメタンガスが生産されており、このことから泥岩層内の遊離ガスが砂岩層内に流動するのではないかという、いわゆる泥岩説が唱えられている。この泥岩説を検証する実験研究の結果、生産ガス水比が大きくなる挙動は泥岩から遊離メタンガスが供給されることによって生じていると考察されている(非特許文献3)。 The ratio of the amount of methane gas produced in a water-soluble natural gas field to the amount of water matches the saturated gas / water ratio with respect to the pressure and temperature of the sandstone layer containing methane gas. From this, it is considered that most of the natural gas produced in the water-soluble natural gas field is methane gas contained in the brine collected from the sandstone formation which is an aquifer and not methane gas contained in the mudstone formation.
On the other hand, in some areas of the South Kanto gas field, methane gas exceeding the saturated gas water ratio is produced, and so the free gas in the mudstone layer may flow into the sandstone layer, so-called mudstone There is a theory. As a result of the experimental study to verify this mudstone theory, it is considered that the behavior in which the production gas water ratio increases is caused by the supply of free methane gas from mudstone (Non-patent Document 3).
また、新潟地方の水溶性ガス田では、生産を停止した坑井において再び生産が可能になった場合、一時的に高いガス水比で生産される現象が確認された。このような現象の要因は、上記の泥岩説を踏まえて推察すると、泥岩層内から移動したメタンガスが砂岩層内に自由度の高い状態で存在し、周辺と比べて比較的地表から浅い地層にあるその坑井に移動、集積したことによると考えられる。
Also, in the water-soluble gas field in the Niigata region, when production was possible again in the well where production was stopped, it was confirmed that the product was temporarily produced at a high gas / water ratio. The cause of such a phenomenon is inferred from the mudstone theory described above, methane gas that has moved from within the mudstone layer is present in the sandstone layer with a high degree of freedom, and the surface is relatively shallow compared to the surroundings. This is thought to be due to the movement and accumulation in a well.
泥岩層は軟質な泥岩からなり、メタンの浸透率は0.002~0.008mdと砂岩に比べて非常に小さいが、空隙率は30~40%であり砂岩層と同様の値を示す。泥岩層内の空隙には、メタンガスが溶け込んだ地層水が含まれていると考えられる。また、泥岩層には多様な鉱物粒子が含まれており、それら鉱物粒子の周囲には多量のメタン分子が吸着されていると考えられる。
このように泥岩層内に存在するメタンは、鉱物粒子への吸着量及び空隙を満たす水への溶解量が飽和状態になると、砂岩層に移動して鹹水に溶解すると考えられる。 The mudstone layer is composed of soft mudstone, and the permeability of methane is 0.002 to 0.008 md, which is very small compared to sandstone, but the porosity is 30 to 40%, which is the same value as the sandstone layer. The voids in the mudstone layer are thought to contain formation water in which methane gas has dissolved. The mudstone layer contains various mineral particles, and it is thought that a large amount of methane molecules are adsorbed around these mineral particles.
Thus, it is considered that the methane present in the mudstone layer moves to the sandstone layer and dissolves in the brine when the adsorption amount to the mineral particles and the dissolution amount in the water filling the voids become saturated.
このように泥岩層内に存在するメタンは、鉱物粒子への吸着量及び空隙を満たす水への溶解量が飽和状態になると、砂岩層に移動して鹹水に溶解すると考えられる。 The mudstone layer is composed of soft mudstone, and the permeability of methane is 0.002 to 0.008 md, which is very small compared to sandstone, but the porosity is 30 to 40%, which is the same value as the sandstone layer. The voids in the mudstone layer are thought to contain formation water in which methane gas has dissolved. The mudstone layer contains various mineral particles, and it is thought that a large amount of methane molecules are adsorbed around these mineral particles.
Thus, it is considered that the methane present in the mudstone layer moves to the sandstone layer and dissolves in the brine when the adsorption amount to the mineral particles and the dissolution amount in the water filling the voids become saturated.
泥岩層内のメタン量は、非特許文献4のデータを引用すると、泥岩層深度1000m、空隙率40%の場合、泥岩層1立方メートル当たり吸着量は10立方メートル、空隙内を満たした水中の溶解量は0.8立方メートルと見積もられた。泥岩層に存在する吸着メタンと溶解メタンの総量は、砂岩層1立方メートル当たりに存在する溶解メタン量0.8立方メートルを上回ると推測される。
The amount of methane in the mudstone layer is quoted from the data of Non-Patent Document 4. When the mudstone layer depth is 1000 m and the porosity is 40%, the adsorption amount per cubic meter of mudstone layer is 10 cubic meters, and the dissolved amount in water filling the voids. Was estimated to be 0.8 cubic meters. The total amount of adsorbed methane and dissolved methane present in the mudstone layer is estimated to exceed the amount of dissolved methane present per 0.8 meter of sandstone layer.
水溶性天然ガス田において生産されるメタンガスの量と水量との比率は、メタンガスを含む砂岩層の圧力、温度に対する飽和ガス/水比に符合する。このことから、水溶性天然ガス田において生産される天然ガスはほとんどが帯水層である砂岩層から回収された鹹水に含まれるメタンガスであり、泥岩層に含まれるメタンガスではないと考えられる。
The ratio of the amount of methane gas produced in the water-soluble natural gas field to the amount of water matches the saturated gas / water ratio with respect to the pressure and temperature of the sandstone layer containing methane gas. From this, it is considered that most of the natural gas produced in the water-soluble natural gas field is methane gas contained in the brine collected from the sandstone formation which is an aquifer and not methane gas contained in the mudstone formation.
上記のように、泥岩層にもメタンガスが多く存在すると推測されるが、現在の生産方法では、泥岩層に存在するであろうメタンガスを採掘するには至っていない。その要因としては、泥岩層内のメタンの存在に関する研究が進んでおらず、その結果、それを回収する技術についても提案がされていないことが挙げられる。
本発明は上記の事情を考慮してなされたものであり、水溶性天然ガス田において、砂岩層からだけでなく、泥岩層に含まれるメタンガスの採掘を可能にする水溶性天然ガスの採掘方法を提供することを目的とする。 As described above, it is speculated that a large amount of methane gas is also present in the mudstone layer, but the current production method has not led to the extraction of methane gas that would be present in the mudstone layer. The reason for this is that research on the existence of methane in the mudstone layer has not progressed, and as a result, no technology has been proposed to recover it.
The present invention has been made in view of the above circumstances, and in a water-soluble natural gas field, there is provided a water-soluble natural gas mining method that enables mining of methane gas contained in a mudstone layer as well as from a sandstone layer. The purpose is to provide.
本発明は上記の事情を考慮してなされたものであり、水溶性天然ガス田において、砂岩層からだけでなく、泥岩層に含まれるメタンガスの採掘を可能にする水溶性天然ガスの採掘方法を提供することを目的とする。 As described above, it is speculated that a large amount of methane gas is also present in the mudstone layer, but the current production method has not led to the extraction of methane gas that would be present in the mudstone layer. The reason for this is that research on the existence of methane in the mudstone layer has not progressed, and as a result, no technology has been proposed to recover it.
The present invention has been made in view of the above circumstances, and in a water-soluble natural gas field, there is provided a water-soluble natural gas mining method that enables mining of methane gas contained in a mudstone layer as well as from a sandstone layer. The purpose is to provide.
本発明は、砂岩層と泥岩層とが上下に隣り合って存在する地層構造を有するガス田からの水溶性天然ガスの採掘方法であって、
前記ガス田に掘削された圧入井を通じて前記ガス田にガスを圧入することにより、前記泥岩層中のメタンを前記ガスと置換する工程と、
前記ガスと置換された前記メタンを、前記ガス田に掘削された生産井を通じて採取する工程とを備える。 The present invention is a method for mining water-soluble natural gas from a gas field having a geological structure in which a sandstone layer and a mudstone layer are adjacent to each other vertically,
Substituting methane in the mudstone layer with the gas by injecting gas into the gas field through an injection well drilled in the gas field;
Collecting the methane substituted for the gas through a production well excavated in the gas field.
前記ガス田に掘削された圧入井を通じて前記ガス田にガスを圧入することにより、前記泥岩層中のメタンを前記ガスと置換する工程と、
前記ガスと置換された前記メタンを、前記ガス田に掘削された生産井を通じて採取する工程とを備える。 The present invention is a method for mining water-soluble natural gas from a gas field having a geological structure in which a sandstone layer and a mudstone layer are adjacent to each other vertically,
Substituting methane in the mudstone layer with the gas by injecting gas into the gas field through an injection well drilled in the gas field;
Collecting the methane substituted for the gas through a production well excavated in the gas field.
本発明の水溶性天然ガスの採掘方法の第一の態様は、前記ガスの圧入に続き、前記圧入井を通じて前記砂岩層に水を圧入する工程をさらに備える。当該第一の態様において、前記ガスは前記圧入井から前記砂岩層に圧入され、前記砂岩層内の地層水と、前記砂岩層に圧入された前記水との間に、前記水に先んじて圧入された前記ガスのセルが画成され、前記砂岩層に対する前記水の加圧を維持することにより、前記セルが前記圧入井から前記生産井に向けて移動し、前記セルの移動の過程で、前記泥岩層中のメタンが前記セル内の前記ガスと置換され、前記セル内のガス相に移動した前記メタンが、前記地層水と共に前記生産井を通じて採取される。
The first aspect of the water-soluble natural gas mining method of the present invention further includes a step of injecting water into the sandstone layer through the injection well following the injection of the gas. In the first aspect, the gas is injected into the sandstone layer from the injection well, and is injected between the formation water in the sandstone layer and the water injected into the sandstone layer prior to the water. A cell of the generated gas is defined, and by maintaining the pressurization of the water against the sandstone layer, the cell moves from the injection well toward the production well, and in the process of moving the cell, The methane in the mudstone layer is replaced with the gas in the cell, and the methane that has moved to the gas phase in the cell is collected through the production well together with the formation water.
本発明の水溶性天然ガスの採掘方法の第一の態様においては、前記砂岩層への前記ガスの圧入及び前記水の圧入が交互に行なわれてもよい。これにより、前記砂岩層内に複数の前記セルが画成される。そして、前記砂岩層に対する前記ガス又は前記水の加圧を維持することにより、複数の前記セルが前記圧入井から前記生産井に向けて移動する。
In the first aspect of the water-soluble natural gas mining method of the present invention, the gas injection and the water injection into the sandstone layer may be performed alternately. Thereby, a plurality of the cells are defined in the sandstone layer. And the said several cell moves toward the said production well from the said injection well by maintaining the pressurization of the said gas or the said water with respect to the said sandstone layer.
本発明の水溶性天然ガスの採掘方法の上記第一の態様において、前記砂岩層に圧入すべき水は塩分を含む水(例えば鹹水、海水)であることが好ましい。
In the first aspect of the water-soluble natural gas mining method of the present invention, the water to be pressed into the sandstone layer is preferably water containing salt (for example, brine, seawater).
本発明の水溶性天然ガスの採掘方法の上記第一の態様において、前記ガスを前記圧入井から前記泥岩層に圧入してもよい。
In the first aspect of the water-soluble natural gas mining method of the present invention, the gas may be injected into the mudstone layer from the injection well.
本発明の水溶性天然ガスの採掘方法の第二の態様は、前記泥岩層に割れ目を生じさせる工程をさらに備える。当該第二の態様において、前記ガスを前記圧入井から前記割れ目に圧入することにより、前記泥岩層中のメタンが、前記割れ目に圧入された前記ガスと置換されて採取される。
The second aspect of the water-soluble natural gas mining method of the present invention further includes a step of generating a crack in the mudstone layer. In the second aspect, by injecting the gas from the injection well into the crack, methane in the mudstone layer is collected by being replaced with the gas injected into the crack.
本発明の水溶性天然ガスの採掘方法の第三の態様は、前記泥岩層に、該泥岩層の広がる方向に向けて水平坑を掘削する工程をさらに備える。当該第三の態様において、前記水平坑には前記ガスが圧入され、前記泥岩層中のメタンが、前記水平坑に圧入された前記ガスと置換され、前記ガスと置換された前記メタンが前記砂岩層に移動し、前記生産井を通じて採取される。
The third aspect of the water-soluble natural gas mining method of the present invention further includes a step of excavating a horizontal pit in the mudstone layer in a direction in which the mudstone layer spreads. In the third aspect, the gas is injected into the horizontal shaft, the methane in the mudstone layer is replaced with the gas pressed into the horizontal shaft, and the methane replaced with the gas is the sandstone. Move to the bed and be collected through the production well.
本発明の水溶性天然ガスの採掘方法の上記第一、第二、第三のいずれの態様においても、前記ガスは炭酸ガスを含むことが好ましい。
In any of the first, second, and third aspects of the water-soluble natural gas mining method of the present invention, the gas preferably contains carbon dioxide.
本発明の水溶性天然ガスの採掘方法の上記第二、第三の態様においては、前記圧入井を前記生産井として使用してもよい。その場合、前記割れ目に圧入した前記ガスは、前記圧入井を通じて回収される。
In the second and third aspects of the water-soluble natural gas mining method of the present invention, the injection well may be used as the production well. In that case, the gas injected into the crack is recovered through the injection well.
本発明によれば、砂岩層からだけでなく、泥岩層に含まれるメタンガスをも採掘することが可能となる。これにより、水溶性天然ガス田における天然ガスの可採埋蔵量を増やすことができ、地下資源を有効に活用することができる。
また、泥岩層に圧入すべきガスとして炭酸ガスを採用し、炭酸ガスの地下還元を行うことで地球温暖化の阻止抑制を図ることができる。 According to the present invention, it is possible to mine not only the sandstone layer but also methane gas contained in the mudstone layer. Thereby, the recoverable reserves of natural gas in the water-soluble natural gas field can be increased, and underground resources can be effectively utilized.
Moreover, carbon dioxide gas is adopted as a gas to be pressed into the mudstone layer, and the global warming can be prevented and suppressed by performing an underground reduction of the carbon dioxide gas.
また、泥岩層に圧入すべきガスとして炭酸ガスを採用し、炭酸ガスの地下還元を行うことで地球温暖化の阻止抑制を図ることができる。 According to the present invention, it is possible to mine not only the sandstone layer but also methane gas contained in the mudstone layer. Thereby, the recoverable reserves of natural gas in the water-soluble natural gas field can be increased, and underground resources can be effectively utilized.
Moreover, carbon dioxide gas is adopted as a gas to be pressed into the mudstone layer, and the global warming can be prevented and suppressed by performing an underground reduction of the carbon dioxide gas.
(第一実施形態)
本発明の水溶性天然ガスの採掘方法の第一の実施の形態について、図1から図3を参照して説明する。
本発明の第一の実施形態による水溶性天然ガス田を図1に示す。同ガス田の地下には、砂岩層1と泥岩層2a,2b(2)とが交互に隣り合って存在する層(砂泥互層)が形成されている。帯水層である砂岩層1内の空隙には、メタンガスが溶け込んだ地層水が含まれている。泥岩層2には砂岩と同程度の空隙が存在し、その空隙にもメタンガスが溶け込んだ地層水が含まれている。また、泥岩層2には多様な鉱物粒子が含まれており、それら鉱物粒子の周囲には多量のメタン分子が吸着されている。上述したように、泥岩層2には、砂岩層1内に存在する量を上回るほどのメタンガスが存在すると推測される。 (First embodiment)
A first embodiment of the water-soluble natural gas mining method of the present invention will be described with reference to FIGS.
A water-soluble natural gas field according to the first embodiment of the present invention is shown in FIG. Under the gas field, a layer (sand mud alternate layer) in which sandstone layers 1 and mudstone layers 2a and 2b (2) are alternately adjacent to each other is formed. The voids in the sandstone layer 1 which is an aquifer contain formation water in which methane gas is dissolved. The mudstone layer 2 has voids similar to sandstone, and the voids also contain formation water in which methane gas has dissolved. The mudstone layer 2 contains various mineral particles, and a large amount of methane molecules are adsorbed around the mineral particles. As described above, it is estimated that the mudstone layer 2 contains methane gas that exceeds the amount existing in the sandstone layer 1.
本発明の水溶性天然ガスの採掘方法の第一の実施の形態について、図1から図3を参照して説明する。
本発明の第一の実施形態による水溶性天然ガス田を図1に示す。同ガス田の地下には、砂岩層1と泥岩層2a,2b(2)とが交互に隣り合って存在する層(砂泥互層)が形成されている。帯水層である砂岩層1内の空隙には、メタンガスが溶け込んだ地層水が含まれている。泥岩層2には砂岩と同程度の空隙が存在し、その空隙にもメタンガスが溶け込んだ地層水が含まれている。また、泥岩層2には多様な鉱物粒子が含まれており、それら鉱物粒子の周囲には多量のメタン分子が吸着されている。上述したように、泥岩層2には、砂岩層1内に存在する量を上回るほどのメタンガスが存在すると推測される。 (First embodiment)
A first embodiment of the water-soluble natural gas mining method of the present invention will be described with reference to FIGS.
A water-soluble natural gas field according to the first embodiment of the present invention is shown in FIG. Under the gas field, a layer (sand mud alternate layer) in which sandstone layers 1 and
水溶性天然ガス田には、メタンガスが存在する地層に炭酸ガスを圧入するための圧入井10が、上層の泥岩層2aを貫通して砂岩層1に達する深さに掘削されている。また、メタンガスが存在する地層からメタンガスを含む地層水を汲み上げるための生産井20が、圧入井10と同様に砂岩層1に達する深さに掘削されている。圧入井10及び生産井20は、メタンガスを含む地層水の存在が見込める領域を挟み、その領域に対して適切な距離を空けて設置されている。圧入井10、生産井20の深さはどちらも砂岩層1よりも深い泥岩層2bに達している。
In the water-soluble natural gas field, an injection well 10 for injecting carbon dioxide into the formation where methane gas exists is drilled to a depth that reaches the sandstone layer 1 through the upper mudstone layer 2a. Further, a production well 20 for pumping formation water containing methane gas from a formation where methane gas exists is excavated to a depth reaching the sandstone layer 1 like the injection well 10. The injection well 10 and the production well 20 are placed with an appropriate distance between the region where the presence of formation water including methane gas can be expected. Both the injection well 10 and the production well 20 reach the mudstone layer 2b deeper than the sandstone layer 1.
圧入井10の地上に露出したケーシング11の上端には、バルブ12を介して炭酸ガスの供給装置13と、塩分を含む水の供給装置14とが接続されている。
炭酸ガス供給装置13はコンプレッサを含み、炭酸ガスの供給源16から供給される炭酸ガスを、同コンプレッサを使って100気圧若しくはそれ以上に圧縮し、ケーシング11を通じて砂岩層1に圧入する。ケーシング11の管壁には、砂岩層1の深度レベルに穿孔11aが形成されており、炭酸ガスは穿孔11aを介して砂岩層1に供給される。 A carbondioxide supply device 13 and a salt water supply device 14 are connected to the upper end of the casing 11 exposed to the ground of the injection well 10 through a valve 12.
The carbondioxide supply device 13 includes a compressor, compresses the carbon dioxide supplied from the carbon dioxide supply source 16 to 100 atm or more using the compressor, and press-fits into the sandstone layer 1 through the casing 11. A perforation 11a is formed in the pipe wall of the casing 11 at a depth level of the sandstone layer 1, and carbon dioxide is supplied to the sandstone layer 1 through the perforation 11a.
炭酸ガス供給装置13はコンプレッサを含み、炭酸ガスの供給源16から供給される炭酸ガスを、同コンプレッサを使って100気圧若しくはそれ以上に圧縮し、ケーシング11を通じて砂岩層1に圧入する。ケーシング11の管壁には、砂岩層1の深度レベルに穿孔11aが形成されており、炭酸ガスは穿孔11aを介して砂岩層1に供給される。 A carbon
The carbon
なお、上記炭酸ガスとは、不可避不純物を除く主要な組成物がCO2のみからなる高純度炭酸ガスに限らず、不可避不純物を除く主要な組成物として比較的高濃度のCO2を含むものであってもよい。また、ここで使用すべき炭酸ガスの起源としては、発電所や工場など、操業の過程でいわゆる化石燃料を消費してCO2を多量に排出する施設が想定される。
また、炭酸ガスは、砂岩層1の深度レベルに供給される状態では気相ではなく液相、若しくは超臨界の状態に変化する。つまり、地下に供給されたCO2は気相とは限らず、液相又は超臨界相を含むと考えられる。この点は地中のメタンについても同様であるが、下記の説明では便宜上「炭酸ガス」、「メタンガス」と表現する。 The carbon dioxide gas is not limited to a high-purity carbon dioxide gas in which the main composition excluding inevitable impurities is composed of only CO 2, but contains a relatively high concentration of CO 2 as the main composition excluding inevitable impurities. There may be. Also, the origin of the carbon dioxide gas to be used here is assumed to be a facility that consumes a large amount of CO 2 by consuming so-called fossil fuel in the operation process such as a power plant or factory.
Further, the carbon dioxide gas changes from a gas phase to a liquid phase or a supercritical state when supplied to the depth level of thesandstone layer 1. That is, it is considered that CO 2 supplied underground is not limited to the gas phase but includes a liquid phase or a supercritical phase. Although this point is the same for underground methane, in the following description, it will be expressed as “carbon dioxide gas” and “methane gas” for convenience.
また、炭酸ガスは、砂岩層1の深度レベルに供給される状態では気相ではなく液相、若しくは超臨界の状態に変化する。つまり、地下に供給されたCO2は気相とは限らず、液相又は超臨界相を含むと考えられる。この点は地中のメタンについても同様であるが、下記の説明では便宜上「炭酸ガス」、「メタンガス」と表現する。 The carbon dioxide gas is not limited to a high-purity carbon dioxide gas in which the main composition excluding inevitable impurities is composed of only CO 2, but contains a relatively high concentration of CO 2 as the main composition excluding inevitable impurities. There may be. Also, the origin of the carbon dioxide gas to be used here is assumed to be a facility that consumes a large amount of CO 2 by consuming so-called fossil fuel in the operation process such as a power plant or factory.
Further, the carbon dioxide gas changes from a gas phase to a liquid phase or a supercritical state when supplied to the depth level of the
塩分を含む水の供給装置14は加圧ポンプを含み、塩分を含む水の供給源17から供給される水を、同ポンプを使って炭酸ガスに付与される圧力と同等レベルにまで加圧し、ケーシング11を通じて砂岩層1に供給する。炭酸ガス供給装置13による炭酸ガスの圧入、及び塩水供給装置14による塩水の圧入は、バルブ12を介して選択的に行われる。
The salt water supply device 14 includes a pressurizing pump, and pressurizes water supplied from a salt water source 17 to a level equivalent to the pressure applied to the carbon dioxide gas using the pump. The sandstone layer 1 is supplied through the casing 11. The injection of carbon dioxide by the carbon dioxide supply device 13 and the injection of salt water by the salt water supply device 14 are selectively performed via the valve 12.
炭酸ガス供給装置13を使って砂岩層1に圧入すべきガスには、上記の炭酸ガスではなく空気等から分離・回収される窒素ガス、又はアルゴンガスを使用してもよい。しかしながら、これらを使用する場合、ガス分子の水に対する溶解度は炭酸ガスに比べて非常に小さい。そのため、砂岩層1に圧入された窒素ガス又はアルゴンガスは水中への溶解が期待できず、水から遊離したメタンガスと混合した状態で生産井側に流動するので、後ほどそれらのガスをメタンガスから分離する必要がある。塩水供給装置14を使って砂岩層1に圧入すべき塩水としては、生産井20を通じて地下から汲み上げた鹹水を再利用してもよいし、沿岸部であれば海水を利用してもよい。
The gas to be pressed into the sandstone layer 1 using the carbon dioxide supply device 13 may be nitrogen gas or argon gas separated and recovered from air or the like instead of the carbon dioxide gas. However, when these are used, the solubility of gas molecules in water is much smaller than that of carbon dioxide. Therefore, nitrogen gas or argon gas injected into the sandstone layer 1 cannot be expected to dissolve in water, and flows to the production well side in a state mixed with methane gas released from water. There is a need to. As salt water to be pressed into the sandstone layer 1 using the salt water supply device 14, the brine pumped from the underground through the production well 20 may be reused, or seawater may be used in the coastal area.
生産井20の地上に露出したケーシング21の上端には、バルブ22を介して地層水とメタンガスとの分離装置23が接続されている。分離装置23は、パイプラインを介して天然ガスの生産プラント30に接続されている。また、分離装置23によってメタンガスを分離された地層水は、地層水の回収池31に排水されるようになっている。回収された地層水を上記のごとく地下圧入水として再利用してもよい。なお、採取される地層水(鹹水)に高濃度のヨウ素が含まれているガス田では、分離装置23は回収池31ではなく不図示のヨウ素生産プラントに接続されてもよい。
A separator 23 for separating formation water and methane gas is connected to the upper end of the casing 21 exposed on the ground of the production well 20 through a valve 22. The separation device 23 is connected to a natural gas production plant 30 via a pipeline. The formation water from which the methane gas has been separated by the separation device 23 is drained into the formation water recovery pond 31. The collected formation water may be reused as underground injection water as described above. In the gas field in which high-concentration iodine is contained in the collected formation water (brown water), the separation device 23 may be connected to an iodine production plant (not shown) instead of the recovery pond 31.
上記のように圧入井10及び生産井20、並びにそれらの付帯設備を設置された水溶性天然ガス田においては、以下のようにして水溶性天然ガスの採掘が行なわれる。
まず、バルブ12を炭酸ガス供給装置13に切り替え、圧入井10のケーシング11に形成された穿孔11aを通じて砂岩層1に炭酸ガスを圧入する。所定量の炭酸ガスを砂岩層1に圧入したら、バルブ12を塩水供給装置14に切り替え、同様にケーシング11の穿孔11aを通じて砂岩層1に塩水Wを圧入する。これにより、砂岩層1内には当初から砂岩層1内に存在していた地層水W0と、圧入された塩水Wとの間に、塩水Wに先んじて砂岩層1に圧入された炭酸ガスのセルC1が画成される。 In the water-soluble natural gas field where the injection well 10 and the production well 20 and their incidental facilities are installed as described above, the water-soluble natural gas is mined as follows.
First, thevalve 12 is switched to the carbon dioxide supply device 13, and carbon dioxide is injected into the sandstone layer 1 through the perforations 11 a formed in the casing 11 of the injection well 10. When a predetermined amount of carbon dioxide gas is pressed into the sandstone layer 1, the valve 12 is switched to the saltwater supply device 14, and the saltwater W is pressed into the sandstone layer 1 through the perforations 11 a of the casing 11. As a result, carbon dioxide gas injected into the sandstone layer 1 prior to the salt water W between the formation water W 0 that had existed in the sandstone layer 1 from the beginning and the salt water W that has been injected into the sandstone layer 1. cell C 1 is defined in.
まず、バルブ12を炭酸ガス供給装置13に切り替え、圧入井10のケーシング11に形成された穿孔11aを通じて砂岩層1に炭酸ガスを圧入する。所定量の炭酸ガスを砂岩層1に圧入したら、バルブ12を塩水供給装置14に切り替え、同様にケーシング11の穿孔11aを通じて砂岩層1に塩水Wを圧入する。これにより、砂岩層1内には当初から砂岩層1内に存在していた地層水W0と、圧入された塩水Wとの間に、塩水Wに先んじて砂岩層1に圧入された炭酸ガスのセルC1が画成される。 In the water-soluble natural gas field where the injection well 10 and the production well 20 and their incidental facilities are installed as described above, the water-soluble natural gas is mined as follows.
First, the
セルC1は上下の泥岩層2a,2bにも接しており、セルC1と泥岩層2a,2bとの間では炭酸ガスとメタンとの置換が起こる。詳述すると、図2に示すように、セルC1内の炭酸ガス(CO2)の分子は上下の泥岩層2a,2bに含まれる地層水に溶解し、ヘンリーの分圧の法則に従って当初から泥岩層2a,2bの地層水に溶解していたメタンガス(CH4)の分子と置換する。炭酸ガス分子との置換によって地層水から分離したメタンガスの分子は、泥岩層2a,2bからセルC1に移動する。
また、泥岩層2a,2b内の地層水に溶解した炭酸ガスの分子は、泥岩層2a,2bに含まれる鉱物粒子Pに吸着されたメタンガスの分子と置換する。炭酸ガス分子との置換によって鉱物粒子Pから遊離したメタンガスの分子は、泥岩層2a,2bからセルC1に移動する。
さらに、上記のように地層水に溶解していたメタンガス、及び鉱物粒子Pから遊離したメタンガスに限らず、泥岩層2a,2b内に様々な状態で存在しているメタンガスも炭酸ガスと置換し、泥岩層2a,2bからセルC1に移動する。
炭酸ガスとの置換により泥岩層2a,2bからセルC1にメタンガスが移動することで、セルC1内のガス相はメタンの濃度を増す。その一方で、炭酸ガスが泥岩層2a,2bに含まれる地層水に溶解することで、セルC1内のガス相は炭酸ガスの濃度を低下させるので、セルC1内のガス相では相対的にメタンの濃縮が増加する。 Cell C 1 and below themudstone layer 2a, and also in contact with the 2b, replacement of carbon dioxide and methane occurs between the cell C 1 and mudstone layers 2a, 2b. Specifically, as shown in FIG. 2, carbon dioxide (CO 2 ) molecules in the cell C 1 are dissolved in the formation water contained in the upper and lower mudstone layers 2a and 2b, and from the beginning according to Henry's law of partial pressure. Replace with methane gas (CH 4 ) molecules dissolved in the formation water of the mudstone layers 2a, 2b. Molecules of methane gas separated from the formation water by substitution of the carbon dioxide gas molecules move Doroiwaso 2a, 2b to the cell C 1.
The molecules of carbon dioxide dissolved in the formation water in the mudstone layers 2a and 2b are replaced with the molecules of methane gas adsorbed on the mineral particles P contained in the mudstone layers 2a and 2b. Molecules of free methane gas from the mineral particles P by replacement of the carbon dioxide gas molecules move Doroiwaso 2a, 2b to the cell C 1.
Furthermore, not only the methane gas dissolved in the formation water as described above and the methane gas released from the mineral particles P, but also methane gas existing in various states in the mudstone layers 2a, 2b is replaced with carbon dioxide gas, Doroiwaso 2a, moves from 2b to the cell C 1.
Mudstone layer 2a by replacement with carbon dioxide gas, that methane gas is moved to the cell C 1 from 2b, the gas phase in the cell C 1 increases the concentration of methane. On the other hand, when carbon dioxide gas is dissolved in the formation water contained in Doroiwaso 2a, 2b, the gas phase in the cell C 1 reduces the concentration of carbon dioxide, relative in the gas phase of the cell C 1 The concentration of methane increases.
また、泥岩層2a,2b内の地層水に溶解した炭酸ガスの分子は、泥岩層2a,2bに含まれる鉱物粒子Pに吸着されたメタンガスの分子と置換する。炭酸ガス分子との置換によって鉱物粒子Pから遊離したメタンガスの分子は、泥岩層2a,2bからセルC1に移動する。
さらに、上記のように地層水に溶解していたメタンガス、及び鉱物粒子Pから遊離したメタンガスに限らず、泥岩層2a,2b内に様々な状態で存在しているメタンガスも炭酸ガスと置換し、泥岩層2a,2bからセルC1に移動する。
炭酸ガスとの置換により泥岩層2a,2bからセルC1にメタンガスが移動することで、セルC1内のガス相はメタンの濃度を増す。その一方で、炭酸ガスが泥岩層2a,2bに含まれる地層水に溶解することで、セルC1内のガス相は炭酸ガスの濃度を低下させるので、セルC1内のガス相では相対的にメタンの濃縮が増加する。 Cell C 1 and below the
The molecules of carbon dioxide dissolved in the formation water in the mudstone layers 2a and 2b are replaced with the molecules of methane gas adsorbed on the mineral particles P contained in the mudstone layers 2a and 2b. Molecules of free methane gas from the mineral particles P by replacement of the carbon dioxide gas molecules move
Furthermore, not only the methane gas dissolved in the formation water as described above and the methane gas released from the mineral particles P, but also methane gas existing in various states in the
地中への炭酸ガスの圧入による上記の作用は、下記の実験でも理解できる。すなわち、閉じた空間にメタンを吸着した泥岩を置き、この閉空間に、混合比率の異なる四種のメタン/炭酸ガスの混合ガスを供給して、閉空間内の気相中の炭酸ガス濃度と、泥岩からのメタンの脱着率との関係を調べると、図3に示すグラフのように、気相中の炭酸ガス濃度が高いほど、泥岩への炭酸ガスの接触による泥岩からのメタンの脱着率も高いことが理解できる。また、メタン脱着率の変化については、気相中の炭酸ガス濃度を増加させると、炭酸ガス濃度が80mol%付近までは緩やかな上昇曲線を描き、80mol%を超えると、その上昇がさらに顕著になる傾向が読み取れる。加えて、炭酸ガス濃度とメタン脱着率との関係は、閉じた空間に供給される混合ガスの圧力にほとんど依存しないことも確認できる。
なお、本実験におけるメタン脱着率とは、純メタンの乾燥泥岩への吸着量に対する脱着量の比である。メタン脱着率は、そのままメタンの回収率に置き換えることができる。例えば、メタン20mol%、炭酸ガス80mol%の混合ガスと泥岩とが接触した場合のメタンの最終的な回収率は約60%である。 The above-mentioned action due to the injection of carbon dioxide into the ground can be understood from the following experiment. In other words, mudstone that has adsorbed methane is placed in a closed space, and four types of methane / carbon dioxide mixed gases with different mixing ratios are supplied to this closed space, and the concentration of carbon dioxide in the gas phase in the closed space is determined. Investigating the relationship with the desorption rate of methane from mudstone, as shown in the graph in FIG. 3, the higher the concentration of carbon dioxide in the gas phase, the higher the desorption rate of methane from mudstone due to carbon dioxide contact with the mudstone. It can be understood that it is expensive. As for the change in the methane desorption rate, when the carbon dioxide concentration in the gas phase is increased, a gradual rise curve is drawn until the carbon dioxide concentration is close to 80 mol%, and when the concentration exceeds 80 mol%, the increase becomes more prominent. The tendency to become can be read. In addition, it can be confirmed that the relationship between the carbon dioxide concentration and the methane desorption rate hardly depends on the pressure of the mixed gas supplied to the closed space.
The methane desorption rate in this experiment is the ratio of the desorption amount to the adsorption amount of pure methane on dry mudstone. The methane desorption rate can be directly replaced with the methane recovery rate. For example, when the mixed gas of 20 mol% of methane and 80 mol% of carbon dioxide gas contacts mudstone, the final recovery rate of methane is about 60%.
なお、本実験におけるメタン脱着率とは、純メタンの乾燥泥岩への吸着量に対する脱着量の比である。メタン脱着率は、そのままメタンの回収率に置き換えることができる。例えば、メタン20mol%、炭酸ガス80mol%の混合ガスと泥岩とが接触した場合のメタンの最終的な回収率は約60%である。 The above-mentioned action due to the injection of carbon dioxide into the ground can be understood from the following experiment. In other words, mudstone that has adsorbed methane is placed in a closed space, and four types of methane / carbon dioxide mixed gases with different mixing ratios are supplied to this closed space, and the concentration of carbon dioxide in the gas phase in the closed space is determined. Investigating the relationship with the desorption rate of methane from mudstone, as shown in the graph in FIG. 3, the higher the concentration of carbon dioxide in the gas phase, the higher the desorption rate of methane from mudstone due to carbon dioxide contact with the mudstone. It can be understood that it is expensive. As for the change in the methane desorption rate, when the carbon dioxide concentration in the gas phase is increased, a gradual rise curve is drawn until the carbon dioxide concentration is close to 80 mol%, and when the concentration exceeds 80 mol%, the increase becomes more prominent. The tendency to become can be read. In addition, it can be confirmed that the relationship between the carbon dioxide concentration and the methane desorption rate hardly depends on the pressure of the mixed gas supplied to the closed space.
The methane desorption rate in this experiment is the ratio of the desorption amount to the adsorption amount of pure methane on dry mudstone. The methane desorption rate can be directly replaced with the methane recovery rate. For example, when the mixed gas of 20 mol% of methane and 80 mol% of carbon dioxide gas contacts mudstone, the final recovery rate of methane is about 60%.
上記のプロセスを複数回(本実施形態では4回)繰り返すと、砂岩層1内には、塩水Wを満たされた領域を挟んで複数の炭酸ガスのセルC2~Cnが画成される。セルC2~Cnにおいても、上記のセルC1と同様に泥岩層2a,2bとの間で炭酸ガスとメタンとの置換が起こり、自由な状態となったメタンガスが泥岩層2a,2bから各セルに移動する。
When the above process is repeated a plurality of times (4 times in the present embodiment), a plurality of carbon dioxide cells C 2 to C n are defined in the sandstone layer 1 across the region filled with the salt water W. . Also in the cell C 2 ~ C n, said cell C 1 in the same manner as in mudstone layers 2a, occurs substitution of carbon dioxide and methane with the 2b, methane became free state is Doroiwaso 2a, 2b to Move to each cell.
砂岩層1内に炭酸ガスのセルC1~Cnが画成された状態で、引き続き砂岩層1に対し炭酸ガスまたは塩水の圧入を維持することにより、砂岩層1内には圧入井10から生産井20に向かう地層水の流れが生じる。生産井20においては、砂岩層1に作用する地圧に加えて、砂岩層1内の地層水の流れの作用により、砂岩層1からメタンガスを含む地層水を汲み上げることが可能になる。
In the state where carbon dioxide cells C 1 to C n are defined in the sandstone layer 1, the carbon dioxide gas or salt water is continuously maintained in the sandstone layer 1. The formation water flows toward the production well 20. In the production well 20, in addition to the earth pressure acting on the sandstone layer 1, formation water containing methane gas can be pumped from the sandstone layer 1 by the action of the formation water in the sandstone layer 1.
生産井20を通じて地層水の汲み上げを実施すると、砂岩層1内の地層水の流れに伴い、砂岩層1内の炭酸ガスのセルC1~Cnが圧入井10から生産井20に向けて移動する。セルC1~Cnと泥岩層2a,2bとの界面は、セルC1~Cnの移動に伴い順次更新されるので、各セルと泥岩層2a,2bとの間で起こる炭酸ガスとメタンとの置換は活性を失わず、結果的にセルC1内のガス相ではメタンの濃縮が促進される。セルC1~Cnにおけるガス相の組成は、生産井20に近づくほどメタン濃度を増し、相反して炭酸ガスの濃度を低下させる。
When the formation water is pumped up through the production well 20, the cells C 1 to C n of the carbon dioxide gas in the sandstone layer 1 move from the injection well 10 to the production well 20 with the flow of the formation water in the sandstone layer 1. To do. Since the interfaces between the cells C 1 to C n and the mudstone layers 2a and 2b are sequentially updated as the cells C 1 to C n move, the carbon dioxide gas and methane generated between each cell and the mudstone layers 2a and 2b. the substitution of not lose the activity, concentration of methane is accelerated in the gas phase results to the cell C 1. The composition of the gas phase in the cells C 1 to C n increases the methane concentration as it approaches the production well 20, and conversely decreases the carbon dioxide concentration.
ケーシング21の管壁には、砂岩層1の深度レベルに穿孔21aが形成されており、セルが生産井20に至ると、セルの移動に伴い濃縮されたメタンガス及びその他の水溶性天然ガスが穿孔21aを通じてケーシング21に流入し、砂岩層1から採取される。採取されたガスは、分離装置23により地層水から分離されたメタンガスとともに生産プラント30に搬送され、所望の加工が施されて商業的な需給に供される。
Perforations 21a are formed in the pipe wall of the casing 21 at the depth level of the sandstone layer 1, and when the cell reaches the production well 20, methane gas and other water-soluble natural gas concentrated along with the movement of the cell are perforated. It flows into the casing 21 through 21 a and is collected from the sandstone layer 1. The collected gas is transported to the production plant 30 together with the methane gas separated from the formation water by the separation device 23, subjected to desired processing, and supplied for commercial supply and demand.
上記のように、本発明の採掘方法の第一の実施形態によれば、砂岩層1からだけでなく、泥岩層2a,2bに含まれるメタンガスをも採掘することが可能となる。これにより、水溶性天然ガス田における天然ガスの可採埋蔵量を増やすことができ、地下資源を有効に活用することができる。
また、副次的な効果として、化石燃料を消費した結果として大気中に排出され、地球温暖化の原因のひとつとされる炭酸ガス(二酸化炭素)を地下に還元することで、地球温暖化の阻止抑制を図ることができる。 As described above, according to the first embodiment of the mining method of the present invention, not only thesandstone layer 1 but also the methane gas contained in the mudstone layers 2a and 2b can be mined. Thereby, the recoverable reserves of natural gas in the water-soluble natural gas field can be increased, and underground resources can be effectively utilized.
As a secondary effect, global warming is reduced by reducing carbon dioxide (carbon dioxide), which is discharged into the atmosphere as a result of consumption of fossil fuels and is one of the causes of global warming. Prevention of inhibition can be achieved.
また、副次的な効果として、化石燃料を消費した結果として大気中に排出され、地球温暖化の原因のひとつとされる炭酸ガス(二酸化炭素)を地下に還元することで、地球温暖化の阻止抑制を図ることができる。 As described above, according to the first embodiment of the mining method of the present invention, not only the
As a secondary effect, global warming is reduced by reducing carbon dioxide (carbon dioxide), which is discharged into the atmosphere as a result of consumption of fossil fuels and is one of the causes of global warming. Prevention of inhibition can be achieved.
ところで、上記第一の実施形態では圧入井10及び生産井20を1本ずつ掘削して水溶性天然ガスの採掘を行う例を示したが、圧入井10を通じて砂岩層1に炭酸ガス及び塩水を圧入すると、その進展は方向性をもちにくく全方向的に拡散することも予想される。したがってそのような場合を考慮して圧入井10を囲むように複数の生産井20を掘削し、それぞれの生産井20において天然ガスの採掘を行ってもよい。
By the way, although the example which excavates the injection well 10 and the production well 20 one by one and mines water-soluble natural gas was shown in said 1st embodiment, carbon dioxide gas and salt water were supplied to the sandstone layer 1 through the injection well 10. When press-fitted, the progress is less directional and is expected to diffuse in all directions. Therefore, in consideration of such a case, a plurality of production wells 20 may be excavated so as to surround the injection well 10, and natural gas may be mined in each production well 20.
上記第一の実施形態では、砂岩層1内に複数のセルC1~Cnを画成する例を示したが、ガス田の規模に依ってはセルをひとつとし、後方の塩水に対する加圧を維持することによりセルの移動を行ってもよい。
In the first embodiment, an example in which a plurality of cells C 1 to C n are defined in the sandstone layer 1 has been shown. However, depending on the scale of the gas field, one cell is used, and pressure is applied to the salt water behind. The cell may be moved by maintaining the above.
砂岩層1内に供給する塩水には、ポリアクリルアミド、グアガム等の既知の増粘剤を水相に添加してもよい。塩水に増粘剤を添加して砂岩層1に対する塩水の抵抗を増加させ、砂岩層1中の塩水の進行速度を遅くすることにより、塩水に区画された炭酸ガスのセルと砂岩層2a,2bとの接触時間が拡大する。その結果、炭酸ガスとメタンとの置換が、セルと砂岩層との接触時間の拡大に伴い活発に起こるので、メタンガス生産量の増大が期待できる。さらに、増粘剤の添加は砂岩層1内における炭酸ガスの意図しない進行、すなわち砂岩層1内において炭酸ガスが塩水を押しのけて進行し、セルの画成の用を為さなくなってしまうことをも防止する。
In the salt water supplied into the sandstone layer 1, a known thickener such as polyacrylamide or guar gum may be added to the aqueous phase. By adding a thickener to the salt water to increase the resistance of the salt water to the sandstone layer 1 and slowing the traveling speed of the salt water in the sandstone layer 1, the cells of the carbon dioxide gas and the sandstone layers 2a, 2b partitioned into the salt water Increases contact time with. As a result, the replacement of carbon dioxide with methane occurs actively as the contact time between the cell and the sandstone layer increases, so an increase in methane gas production can be expected. Furthermore, the addition of the thickener means that the carbon dioxide gas is not intended to proceed in the sandstone layer 1, that is, the carbon dioxide gas is pushed through the salt water in the sandstone layer 1 and is no longer used for cell definition. Also prevent.
(第二実施形態)
次に、本発明の水溶性天然ガスの採掘方法の第二の実施の形態について、図4を参照して説明する。
本発明の第二の実施形態においては、図4に示すように、泥岩層2aに、層の広がる方向に割れ目40を生じさせる(fracturing)。その割れ目40に、圧入井10のケーシング11を通じて炭酸ガスを圧入すると、割れ目40と泥岩層2aとの間では、上記第一の実施形態と同様に炭酸ガスとメタンとの置換が起こる。すなわち、割れ目40に供給された高圧の炭酸ガスは泥岩層2aに含まれる地層水に溶解し、その炭酸ガスの分子は、ヘンリーの分圧の法則に従って当初から泥岩層2aの地層水に溶解していたメタンガス(CH4)の分子と置換する。炭酸ガス分子との置換によって地層水から分離したメタンガスの分子は、泥岩層2aから割れ目40の空隙に移動する。
また、泥岩層2a内の地層水に溶解した炭酸ガスの分子は、泥岩層2aに含まれる鉱物粒子Pに吸着されたメタンガスの分子と置換する。炭酸ガス分子との置換によって鉱物粒子Pから遊離したメタンガスの分子も、泥岩層2aから割れ目40の空隙に移動する。
炭酸ガスとの置換により泥岩層2aから割れ目40の空隙にメタンガスが移動することで、割れ目40内のガス相はメタンの濃度を増す。その一方で、炭酸ガスが泥岩層2aに含まれる地層水に溶解することで、割れ目40内のガス相は炭酸ガスの濃度を低下させるので、割れ目40内のガス相では相対的にメタンの濃縮が増加する。 (Second embodiment)
Next, a second embodiment of the water-soluble natural gas mining method of the present invention will be described with reference to FIG.
In the second embodiment of the present invention, as shown in FIG. 4, themudstone layer 2a is fractured in the direction in which the layer spreads (fracturing). When carbon dioxide is injected into the crack 40 through the casing 11 of the injection well 10, substitution between carbon dioxide and methane occurs between the crack 40 and the mudstone layer 2a as in the first embodiment. That is, the high-pressure carbon dioxide gas supplied to the fissure 40 is dissolved in the formation water contained in the mudstone layer 2a, and the carbon dioxide molecules are dissolved in the formation water of the mudstone layer 2a from the beginning according to Henry's law of partial pressure. It replaces the methane gas (CH 4 ) molecules. Methane gas molecules separated from the formation water by substitution with carbon dioxide gas molecules move from the mudstone layer 2a to the voids of the cracks 40.
Further, carbon dioxide gas molecules dissolved in the formation water in themudstone layer 2a are replaced with methane gas molecules adsorbed on the mineral particles P contained in the mudstone layer 2a. Methane gas molecules liberated from the mineral particles P by substitution with carbon dioxide gas molecules also move from the mudstone layer 2a to the gaps of the cracks 40.
When the methane gas moves from themudstone layer 2a to the gap of the crack 40 by the replacement with the carbon dioxide gas, the gas phase in the crack 40 increases the concentration of methane. On the other hand, since carbon dioxide dissolves in the formation water contained in the mudstone layer 2a, the gas phase in the crack 40 reduces the concentration of carbon dioxide, so the gas phase in the crack 40 is relatively concentrated in methane. Will increase.
次に、本発明の水溶性天然ガスの採掘方法の第二の実施の形態について、図4を参照して説明する。
本発明の第二の実施形態においては、図4に示すように、泥岩層2aに、層の広がる方向に割れ目40を生じさせる(fracturing)。その割れ目40に、圧入井10のケーシング11を通じて炭酸ガスを圧入すると、割れ目40と泥岩層2aとの間では、上記第一の実施形態と同様に炭酸ガスとメタンとの置換が起こる。すなわち、割れ目40に供給された高圧の炭酸ガスは泥岩層2aに含まれる地層水に溶解し、その炭酸ガスの分子は、ヘンリーの分圧の法則に従って当初から泥岩層2aの地層水に溶解していたメタンガス(CH4)の分子と置換する。炭酸ガス分子との置換によって地層水から分離したメタンガスの分子は、泥岩層2aから割れ目40の空隙に移動する。
また、泥岩層2a内の地層水に溶解した炭酸ガスの分子は、泥岩層2aに含まれる鉱物粒子Pに吸着されたメタンガスの分子と置換する。炭酸ガス分子との置換によって鉱物粒子Pから遊離したメタンガスの分子も、泥岩層2aから割れ目40の空隙に移動する。
炭酸ガスとの置換により泥岩層2aから割れ目40の空隙にメタンガスが移動することで、割れ目40内のガス相はメタンの濃度を増す。その一方で、炭酸ガスが泥岩層2aに含まれる地層水に溶解することで、割れ目40内のガス相は炭酸ガスの濃度を低下させるので、割れ目40内のガス相では相対的にメタンの濃縮が増加する。 (Second embodiment)
Next, a second embodiment of the water-soluble natural gas mining method of the present invention will be described with reference to FIG.
In the second embodiment of the present invention, as shown in FIG. 4, the
Further, carbon dioxide gas molecules dissolved in the formation water in the
When the methane gas moves from the
炭酸ガスの圧入により、割れ目40内のガス圧力は砂岩層1内のガス圧力よりも高くなる。そのため、割れ目40内に溜まったメタンガスは泥岩層2aから砂岩層1に移動する。また、上記のように地層水に溶解していたメタンガス、及び鉱物粒子Pから遊離したメタンガスに限らず、泥岩層2a内に様々な状態で存在しているメタンガスも、泥岩層2aから割れ目40の空隙に移動する。砂岩層1に移動したメタンガスは、生産井20での汲み上げに伴って地層水とともに砂岩層1内を移動して生産井20に至り、ケーシング21を通じて地層水とともに砂岩層1から採取される。採取されたガスは、分離装置23により地層水から分離されたメタンガスとともに生産プラント30に搬送され、所望の加工が施されて商業的な需給に供される。
Due to the injection of carbon dioxide gas, the gas pressure in the crack 40 becomes higher than the gas pressure in the sandstone layer 1. Therefore, the methane gas accumulated in the crack 40 moves from the mudstone layer 2 a to the sandstone layer 1. Moreover, not only the methane gas dissolved in the formation water as described above and the methane gas liberated from the mineral particles P, but also the methane gas existing in various states in the mudstone layer 2a is also generated from the mudstone layer 2a. Move to the gap. The methane gas that has moved to the sandstone layer 1 moves in the sandstone layer 1 together with the formation water as it is pumped in the production well 20, reaches the production well 20, and is collected from the sandstone layer 1 together with the formation water through the casing 21. The collected gas is transported to the production plant 30 together with the methane gas separated from the formation water by the separation device 23, subjected to desired processing, and supplied for commercial supply and demand.
上記のように、本発明の採掘方法の第二の実施形態によれば、砂岩層1からだけでなく、泥岩層2aに含まれるメタンガスをも採掘することが可能となる。これにより、水溶性天然ガス田における天然ガスの可採埋蔵量を増やすことができ、地下資源を有効に活用することができる。
As described above, according to the second embodiment of the mining method of the present invention, not only the sandstone layer 1 but also the methane gas contained in the mudstone layer 2a can be mined. Thereby, the recoverable reserves of natural gas in the water-soluble natural gas field can be increased, and underground resources can be effectively utilized.
ところで、上記第二の実施形態では砂岩層1よりも浅い泥岩層2aに割れ目40を生じさせているが、砂岩層1よりも深い泥岩層2bに割れ目を生じさせてもよいし、両方の泥岩層2a,2bに割れ目を生じさせてもよい。この場合、圧入井10は砂岩層1をも貫通して下層の泥岩層2bに達する深さに掘削されるべきである。
また、割れ目40内のガスが流動して砂岩層1を掃攻すると、その進展は方向性をもちにくく全方向的に拡散することも予想される。したがってそのような場合を考慮して圧入井10を囲むように複数の生産井20を掘削し、それぞれの生産井20において天然ガスの採掘を行ってもよい。 In the second embodiment, thecrack 40 is generated in the mudstone layer 2a shallower than the sandstone layer 1, but a crack may be generated in the mudstone layer 2b deeper than the sandstone layer 1, or both mudstones. You may make a crack in the layers 2a and 2b. In this case, the injection well 10 should be excavated to a depth that penetrates the sandstone layer 1 and reaches the lower mudstone layer 2b.
Moreover, when the gas in thecrack 40 flows and sweeps the sandstone layer 1, it is expected that the progress is less directional and diffuses in all directions. Therefore, in consideration of such a case, a plurality of production wells 20 may be excavated so as to surround the injection well 10, and natural gas may be mined in each production well 20.
また、割れ目40内のガスが流動して砂岩層1を掃攻すると、その進展は方向性をもちにくく全方向的に拡散することも予想される。したがってそのような場合を考慮して圧入井10を囲むように複数の生産井20を掘削し、それぞれの生産井20において天然ガスの採掘を行ってもよい。 In the second embodiment, the
Moreover, when the gas in the
(第三実施形態)
次に、本発明の水溶性天然ガスの採掘方法の第三の実施の形態について、図5を参照して説明する。
本発明の第三の実施形態においては、圧入井が生産井としても使用されるため、図5に示すように、水溶性天然ガス田には圧入井110のみが掘削され、生産井は掘削されていない。圧入井110は上層の泥岩層2aに達する深さに掘削され、砂岩層1には達していない。圧入井110が生産井を兼ねるため、分離装置23は圧入井110に接続されている。 (Third embodiment)
Next, a third embodiment of the water-soluble natural gas mining method of the present invention will be described with reference to FIG.
In the third embodiment of the present invention, since the injection well is also used as a production well, as shown in FIG. 5, only the injection well 110 is excavated in the water-soluble natural gas field, and the production well is excavated. Not. The injection well 110 is excavated to a depth reaching theupper mudstone layer 2 a and does not reach the sandstone layer 1. Since the injection well 110 also serves as a production well, the separation device 23 is connected to the injection well 110.
次に、本発明の水溶性天然ガスの採掘方法の第三の実施の形態について、図5を参照して説明する。
本発明の第三の実施形態においては、圧入井が生産井としても使用されるため、図5に示すように、水溶性天然ガス田には圧入井110のみが掘削され、生産井は掘削されていない。圧入井110は上層の泥岩層2aに達する深さに掘削され、砂岩層1には達していない。圧入井110が生産井を兼ねるため、分離装置23は圧入井110に接続されている。 (Third embodiment)
Next, a third embodiment of the water-soluble natural gas mining method of the present invention will be described with reference to FIG.
In the third embodiment of the present invention, since the injection well is also used as a production well, as shown in FIG. 5, only the injection well 110 is excavated in the water-soluble natural gas field, and the production well is excavated. Not. The injection well 110 is excavated to a depth reaching the
泥岩層2aに、上記第二の実施形態と同様に割れ目40を生じさせ、その割れ目40に圧入井110のケーシング111を通じて炭酸ガスを圧入すると、割れ目40と泥岩層2aとの間では、上記第二の実施形態と同様に炭酸ガス分子とメタン分子との置換が起こり、割れ目40内のガス相は相対的にメタンの濃縮を増加させる。
When the crack 40 is generated in the mudstone layer 2a as in the second embodiment, and carbon dioxide gas is injected into the crack 40 through the casing 111 of the press-fitting well 110, the gap 40 and the mudstone layer 2a As in the second embodiment, the replacement of carbon dioxide molecules with methane molecules occurs, and the gas phase in the crack 40 relatively increases the concentration of methane.
ところで、上記第二の実施形態とは異なり、圧入井110は砂岩層1には達していないので、圧入井110に対する炭酸ガスの加圧を解除すれば、メタン濃度を増した割れ目40内のガスはケーシング111を逆流して泥岩層2aから採取される。採取されたガスは、分離装置23により地層水から分離されたメタンガスとともに生産プラント30に搬送され、所望の加工が施されて商業的な需給に供される。
By the way, unlike the said 2nd embodiment, since the injection well 110 has not reached the sandstone layer 1, if the pressurization of the carbon dioxide gas with respect to the injection well 110 is cancelled | released, the gas in the crack 40 which increased the methane density | concentration Is collected from the mudstone layer 2a by flowing back through the casing 111. The collected gas is transported to the production plant 30 together with the methane gas separated from the formation water by the separation device 23, subjected to desired processing, and supplied for commercial supply and demand.
上記のように、本発明の採掘方法の第三の実施形態によれば、泥岩層2aに含まれるメタンガスを、砂岩層1に含まれるメタンガスと共にではなくそれ単独でも採掘することが可能となる。これにより、例えば豊富なメタン含有量が確認できる泥岩層2が存在するものの、砂岩層1が水溶性天然ガスの採掘に不向きな地下構造のガス田であっても、泥岩層2から天然ガスを採掘することができ、地下資源を有効に活用することができる。
また、圧入井が生産井を兼ねるので、比較的小規模の天然ガス田に好適に用いることができる。 As described above, according to the third embodiment of the mining method of the present invention, the methane gas contained in themudstone layer 2a can be mined alone, not together with the methane gas contained in the sandstone layer 1. As a result, for example, although there is a mudstone layer 2 where abundant methane content can be confirmed, even if the sandstone layer 1 is an underground gas field unsuitable for mining water-soluble natural gas, natural gas is extracted from the mudstone layer 2. It can be mined and underground resources can be used effectively.
Moreover, since the injection well serves as the production well, it can be suitably used for a relatively small natural gas field.
また、圧入井が生産井を兼ねるので、比較的小規模の天然ガス田に好適に用いることができる。 As described above, according to the third embodiment of the mining method of the present invention, the methane gas contained in the
Moreover, since the injection well serves as the production well, it can be suitably used for a relatively small natural gas field.
(第四実施形態)
次に、本発明の水溶性天然ガスの採掘方法の第四の実施の形態について、図6を参照して説明する。
本発明の第四の実施形態においては、図6に示すように、泥岩層2aに達する縦坑の下端に水平坑を掘削して圧入井210とする。水平坑に挿通されるケーシング41には、多数の穿孔41aが形成されている。炭酸ガスを、圧入井210のケーシング41の穿孔41aを通じて泥岩層2aに圧入すると、炭酸ガスは泥岩層2aを介して砂岩層1に供給される。
なお、本実施形態では水平坑を上層の泥岩層2aにのみ掘削しているが、下層の泥岩層2bに掘削してもよいし、両方に掘削してもよい。 (Fourth embodiment)
Next, a fourth embodiment of the water-soluble natural gas mining method of the present invention will be described with reference to FIG.
In the fourth embodiment of the present invention, as shown in FIG. 6, a horizontal well is excavated at the lower end of the vertical shaft reaching themudstone layer 2 a to form the injection well 210. A large number of perforations 41a are formed in the casing 41 inserted through the horizontal pit. When carbon dioxide is injected into the mudstone layer 2a through the perforations 41a of the casing 41 of the injection well 210, the carbon dioxide gas is supplied to the sandstone layer 1 through the mudstone layer 2a.
In this embodiment, the horizontal pit is excavated only in theupper mudstone layer 2a, but it may be excavated in the lower mudstone layer 2b, or may be excavated in both.
次に、本発明の水溶性天然ガスの採掘方法の第四の実施の形態について、図6を参照して説明する。
本発明の第四の実施形態においては、図6に示すように、泥岩層2aに達する縦坑の下端に水平坑を掘削して圧入井210とする。水平坑に挿通されるケーシング41には、多数の穿孔41aが形成されている。炭酸ガスを、圧入井210のケーシング41の穿孔41aを通じて泥岩層2aに圧入すると、炭酸ガスは泥岩層2aを介して砂岩層1に供給される。
なお、本実施形態では水平坑を上層の泥岩層2aにのみ掘削しているが、下層の泥岩層2bに掘削してもよいし、両方に掘削してもよい。 (Fourth embodiment)
Next, a fourth embodiment of the water-soluble natural gas mining method of the present invention will be described with reference to FIG.
In the fourth embodiment of the present invention, as shown in FIG. 6, a horizontal well is excavated at the lower end of the vertical shaft reaching the
In this embodiment, the horizontal pit is excavated only in the
泥岩層2aに炭酸ガスを圧入すると、泥岩層2a内では、上記第一の実施形態と同様に炭酸ガスとメタンガスとの置換が起こる。すなわち、ケーシング41の穿孔41aを介して泥岩層2aに供給された高圧の炭酸ガスは泥岩層2aに含まれる地層水に溶解し、その炭酸ガスの分子は、ヘンリーの分圧の法則に従って当初から泥岩層2aの地層水に溶解していたメタンガスの分子と置換し、地層水から分離する。
また、泥岩層2a内の地層水に溶解した炭酸ガスの分子は、泥岩層2aに含まれる鉱物粒子Pに吸着されたメタンガスの分子と置換し、鉱物粒子Pから遊離する。
炭酸ガスの圧入により、泥岩層2a内のガス圧力は砂岩層1内のガス圧力よりも高くなる。そのため、炭酸ガスと置換して自由な状態となったメタンガスは、泥岩層2aと砂岩層1との圧力差により泥岩層2aから砂岩層1に移動する。
また、鉱物粒子Pから遊離したメタンガスの分子も、泥岩層2aと砂岩層1との圧力差により泥岩層2aから砂岩層1に移動する。
さらに、上記のように地層水に溶解していたメタンガス、及び鉱物粒子Pから遊離したメタンガスに限らず、泥岩層2a内に様々な状態で存在しているメタンガスも、泥岩層2aと砂岩層1との圧力差により泥岩層2aから砂岩層1に移動する。 When carbon dioxide gas is injected into themudstone layer 2a, carbon dioxide gas and methane gas are replaced in the mudstone layer 2a as in the first embodiment. That is, the high-pressure carbon dioxide gas supplied to the mudstone layer 2a through the perforation 41a of the casing 41 dissolves in the formation water contained in the mudstone layer 2a, and the molecules of the carbon dioxide gas are originally from the beginning according to Henry's law of partial pressure. It replaces the methane gas molecules dissolved in the formation water of the mudstone layer 2a and separates it from the formation water.
Further, the carbon dioxide gas molecules dissolved in the formation water in themudstone layer 2a are replaced with the methane gas molecules adsorbed on the mineral particles P contained in the mudstone layer 2a and are released from the mineral particles P.
The gas pressure in themudstone layer 2a becomes higher than the gas pressure in the sandstone layer 1 by the injection of carbon dioxide. For this reason, the methane gas that is in a free state by replacing with carbon dioxide gas moves from the mudstone layer 2a to the sandstone layer 1 due to the pressure difference between the mudstone layer 2a and the sandstone layer 1.
Methane gas molecules liberated from the mineral particles P also move from themudstone layer 2a to the sandstone layer 1 due to a pressure difference between the mudstone layer 2a and the sandstone layer 1.
Furthermore, not only the methane gas dissolved in the formation water as described above and the methane gas liberated from the mineral particles P, but also the methane gas existing in various states in themudstone layer 2a is also the mudstone layer 2a and the sandstone layer 1 It moves from the mudstone layer 2a to the sandstone layer 1 due to the pressure difference.
また、泥岩層2a内の地層水に溶解した炭酸ガスの分子は、泥岩層2aに含まれる鉱物粒子Pに吸着されたメタンガスの分子と置換し、鉱物粒子Pから遊離する。
炭酸ガスの圧入により、泥岩層2a内のガス圧力は砂岩層1内のガス圧力よりも高くなる。そのため、炭酸ガスと置換して自由な状態となったメタンガスは、泥岩層2aと砂岩層1との圧力差により泥岩層2aから砂岩層1に移動する。
また、鉱物粒子Pから遊離したメタンガスの分子も、泥岩層2aと砂岩層1との圧力差により泥岩層2aから砂岩層1に移動する。
さらに、上記のように地層水に溶解していたメタンガス、及び鉱物粒子Pから遊離したメタンガスに限らず、泥岩層2a内に様々な状態で存在しているメタンガスも、泥岩層2aと砂岩層1との圧力差により泥岩層2aから砂岩層1に移動する。 When carbon dioxide gas is injected into the
Further, the carbon dioxide gas molecules dissolved in the formation water in the
The gas pressure in the
Methane gas molecules liberated from the mineral particles P also move from the
Furthermore, not only the methane gas dissolved in the formation water as described above and the methane gas liberated from the mineral particles P, but also the methane gas existing in various states in the
ところで、上記のメタンガスの移動の過程において、メタンガスとともに炭酸ガスも移動する可能性があるが、砂岩層1に移動した炭酸ガスは、砂岩層1に存在する地層水(鹹水)に溶解しているメタンと分子置換を生じて地層水に溶解する。この結果、砂岩層1内には、泥岩層2aから移動したメタンガスと、砂岩層1内の地層水から遊離したメタンガスとに起因してメタン濃度の高いガス相が発生する。泥岩層2aから移動したメタンガスと、地層水から遊離したメタンガスの総量は、砂岩層1内の地層水に溶解するメタンの量を大きく上回ると推測される。
By the way, in the process of movement of the methane gas, there is a possibility that the carbon dioxide gas may move together with the methane gas, but the carbon dioxide gas that has moved to the sandstone layer 1 is dissolved in the formation water (flooded water) existing in the sandstone layer 1. Dissolves in formation water with molecular replacement with methane. As a result, a gas phase having a high methane concentration is generated in the sandstone layer 1 due to the methane gas moved from the mudstone layer 2 a and the methane gas released from the formation water in the sandstone layer 1. It is estimated that the total amount of methane gas moved from the mudstone layer 2a and methane gas released from the formation water greatly exceeds the amount of methane dissolved in the formation water in the sandstone layer 1.
砂岩層1内の高濃度のメタンガスは、生産井20での汲み上げに伴って地層水とともに砂岩層1内を移動して生産井20に至り、ケーシング21を通じて地層水とともに砂岩層1から採取される。採取されたガスは、分離装置23により地層水から分離されたメタンガスとともに生産プラント30に搬送され、所望の加工が施されて商業的な需給に供される。
The high-concentration methane gas in the sandstone layer 1 moves in the sandstone layer 1 together with the formation water as it is pumped in the production well 20, reaches the production well 20, and is collected from the sandstone layer 1 together with the formation water through the casing 21. . The collected gas is transported to the production plant 30 together with the methane gas separated from the formation water by the separation device 23, subjected to desired processing, and supplied for commercial supply and demand.
上記のように、本発明の採掘法の第四の実施形態によれば、上記第二の実施形態と同様に、砂岩層1からだけでなく、泥岩層2aに含まれるメタンガスをも採掘することが可能となる。これにより、水溶性天然ガス田における天然ガスの可採埋蔵量を増やすことができ、地下資源を有効に活用することができる。
As described above, according to the fourth embodiment of the mining method of the present invention, not only the sandstone layer 1 but also the methane gas contained in the mudstone layer 2a is mined as in the second embodiment. Is possible. Thereby, the recoverable reserves of natural gas in the water-soluble natural gas field can be increased, and underground resources can be effectively utilized.
本発明は、泥岩層と砂岩層とが上下に隣り合って存在する地層構造を有するガス田からの水溶性天然ガスの採掘方法に関し、特に、今まで提案されてはいなかった泥岩層に含まれるメタンガスの採掘を可能にする方法に関する。
本発明によれば、水溶性天然ガス田における天然ガスの可採埋蔵量を増やすことができ、地下資源を有効に活用することができる。 The present invention relates to a method for mining water-soluble natural gas from a gas field having a geological structure in which a mudstone layer and a sandstone layer are adjacent to each other vertically, and is particularly included in a mudstone layer that has not been proposed so far. The present invention relates to a method that enables mining of methane gas.
ADVANTAGE OF THE INVENTION According to this invention, the recoverable reserve of the natural gas in a water-soluble natural gas field can be increased, and an underground resource can be utilized effectively.
本発明によれば、水溶性天然ガス田における天然ガスの可採埋蔵量を増やすことができ、地下資源を有効に活用することができる。 The present invention relates to a method for mining water-soluble natural gas from a gas field having a geological structure in which a mudstone layer and a sandstone layer are adjacent to each other vertically, and is particularly included in a mudstone layer that has not been proposed so far. The present invention relates to a method that enables mining of methane gas.
ADVANTAGE OF THE INVENTION According to this invention, the recoverable reserve of the natural gas in a water-soluble natural gas field can be increased, and an underground resource can be utilized effectively.
1 砂岩層、
2a,2b(2) 泥岩層、
10 圧入井、
11 ケーシング、
11a 穿孔、
12 バルブ、
13 炭酸ガス供給装置、
14 塩水供給装置、
16 炭酸ガス供給源、
20 生産井、
21 ケーシング、
22 バルブ、
23 分離装置、
30 天然ガス生産プラント、
31 地層水回収池、
40 割れ目、
41 ケーシング、
41a 穿孔、
110 圧入井、
111 ケーシング、
210 圧入井
C1~Cn セル、
P 鉱物粒子、
W0 地層水、
W 塩水 1 sandstone layer,
2a, 2b (2) mudstone layer,
10 injection wells,
11 casing,
11a perforation,
12 valves,
13 Carbon dioxide supply device,
14 salt water supply device,
16 Carbon dioxide supply source,
20 production wells,
21 casing,
22 valves,
23 separator,
30 Natural gas production plant,
31 Formation water recovery pond,
40 cracks,
41 casing,
41a perforation,
110 injection well,
111 casing,
210 injection well C 1 -C n cell,
P mineral particles,
W 0 formation water,
W salt water
2a,2b(2) 泥岩層、
10 圧入井、
11 ケーシング、
11a 穿孔、
12 バルブ、
13 炭酸ガス供給装置、
14 塩水供給装置、
16 炭酸ガス供給源、
20 生産井、
21 ケーシング、
22 バルブ、
23 分離装置、
30 天然ガス生産プラント、
31 地層水回収池、
40 割れ目、
41 ケーシング、
41a 穿孔、
110 圧入井、
111 ケーシング、
210 圧入井
C1~Cn セル、
P 鉱物粒子、
W0 地層水、
W 塩水 1 sandstone layer,
2a, 2b (2) mudstone layer,
10 injection wells,
11 casing,
11a perforation,
12 valves,
13 Carbon dioxide supply device,
14 salt water supply device,
16 Carbon dioxide supply source,
20 production wells,
21 casing,
22 valves,
23 separator,
30 Natural gas production plant,
31 Formation water recovery pond,
40 cracks,
41 casing,
41a perforation,
110 injection well,
111 casing,
210 injection well C 1 -C n cell,
P mineral particles,
W 0 formation water,
W salt water
Claims (8)
- 砂岩層と泥岩層とが上下に隣り合って存在する地層構造を有するガス田からの水溶性天然ガスの採掘方法であって、
前記ガス田に掘削された圧入井を通じて前記ガス田にガスを圧入することにより、前記泥岩層中のメタンを前記ガスと置換する工程と、
前記ガスと置換された前記メタンを、前記ガス田に掘削された生産井を通じて採取する工程とを備える水溶性天然ガスの採掘方法。 A method for mining water-soluble natural gas from a gas field having a geological structure in which a sandstone layer and a mudstone layer are adjacent to each other vertically,
Substituting methane in the mudstone layer with the gas by injecting gas into the gas field through an injection well drilled in the gas field;
A method for mining water-soluble natural gas, comprising: collecting the methane substituted for the gas through a production well excavated in the gas field. - 前記ガスの圧入に続き、前記圧入井を通じて前記砂岩層に水を圧入する工程をさらに備え、
前記ガスは前記圧入井から前記砂岩層に圧入され、
前記砂岩層内の地層水と、前記砂岩層に圧入された前記水との間に、前記水に先んじて圧入された前記ガスのセルが画成され、
前記砂岩層に対する前記水の加圧を維持することにより、前記セルが前記圧入井から前記生産井に向けて移動し、
前記セルの移動の過程で、前記泥岩層中のメタンが前記セル内の前記ガスと置換され、
前記セル内のガス相に移動した前記メタンが、前記地層水と共に前記生産井を通じて採取される請求項1に記載の水溶性天然ガスの採掘方法。 Following the injection of the gas, further comprising the step of injecting water into the sandstone layer through the injection well,
The gas is injected into the sandstone layer from the injection well,
Between the formation water in the sandstone layer and the water injected into the sandstone layer, a cell of the gas injected prior to the water is defined,
By maintaining the pressurization of the water against the sandstone layer, the cell moves from the injection well toward the production well,
In the process of moving the cell, methane in the mudstone layer is replaced with the gas in the cell,
The water-soluble natural gas mining method according to claim 1, wherein the methane that has moved to the gas phase in the cell is collected through the production well together with the formation water. - 前記砂岩層への前記ガスの圧入及び前記水の圧入が交互に行なわれることにより、前記砂岩層内に複数の前記セルが画成され、
前記砂岩層に対する前記ガス又は前記水の加圧を維持することにより、複数の前記セルが前記圧入井から前記生産井に向けて移動する、請求項2に記載の水溶性天然ガスの採掘方法。 A plurality of the cells are defined in the sandstone layer by alternately injecting the gas and the water into the sandstone layer,
The water-soluble natural gas mining method according to claim 2, wherein the plurality of cells move from the injection well toward the production well by maintaining pressurization of the gas or the water with respect to the sandstone layer. - 前記砂岩層に圧入すべき水は塩分を含む請求項2又は3に記載の水溶性天然ガスの採掘方法。 The water-soluble natural gas mining method according to claim 2 or 3, wherein the water to be injected into the sandstone layer contains salt.
- 前記ガスを前記圧入井から前記泥岩層に圧入する請求項1に記載の水溶性天然ガスの採掘方法。 The water-soluble natural gas mining method according to claim 1, wherein the gas is injected from the injection well into the mudstone layer.
- 前記泥岩層に割れ目を生じさせる工程をさらに備え、前記ガスを前記圧入井から前記割れ目に圧入する請求項5に記載の水溶性天然ガスの採掘方法。 The method for mining water-soluble natural gas according to claim 5, further comprising a step of generating a crack in the mudstone layer, wherein the gas is injected into the crack from the injection well.
- 前記泥岩層に、該泥岩層の広がる方向に向けて水平坑を掘削する工程をさらに備え、
前記水平坑に前記ガスが圧入され、前記泥岩層中のメタンが、前記水平坑に圧入された前記ガスと置換され、
前記ガスと置換された前記メタンが前記砂岩層に移動し、前記生産井を通じて採取される請求項5に記載の水溶性天然ガスの採掘方法。 The mudstone layer further comprises a step of excavating a horizontal pit toward the spreading direction of the mudstone layer,
The gas is injected into the horizontal shaft, and the methane in the mudstone layer is replaced with the gas injected into the horizontal shaft,
The method for mining water-soluble natural gas according to claim 5, wherein the methane substituted with the gas moves to the sandstone layer and is collected through the production well. - 前記ガスは炭酸ガスを含む請求項1から7のいずれか一項に記載の水溶性天然ガスの採掘方法。 The water-soluble natural gas mining method according to any one of claims 1 to 7, wherein the gas includes carbon dioxide gas.
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JP2019504223A (en) * | 2015-12-22 | 2019-02-14 | エイカー ソリューションズ エーエス | Production of undersea methane hydrate |
JP2020012259A (en) * | 2018-07-13 | 2020-01-23 | 横河電機株式会社 | Apparatus, method and program for state estimation of natural resource to be collected |
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JP2019504223A (en) * | 2015-12-22 | 2019-02-14 | エイカー ソリューションズ エーエス | Production of undersea methane hydrate |
US10968707B2 (en) | 2015-12-22 | 2021-04-06 | Aker Solutions As | Subsea methane hydrate production |
JP2020012259A (en) * | 2018-07-13 | 2020-01-23 | 横河電機株式会社 | Apparatus, method and program for state estimation of natural resource to be collected |
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JPWO2016104448A1 (en) | 2017-08-17 |
JP6327730B2 (en) | 2018-05-23 |
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