CN116263084A - Drilling and production system and method for offshore natural gas hydrate development - Google Patents
Drilling and production system and method for offshore natural gas hydrate development Download PDFInfo
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- CN116263084A CN116263084A CN202111560972.2A CN202111560972A CN116263084A CN 116263084 A CN116263084 A CN 116263084A CN 202111560972 A CN202111560972 A CN 202111560972A CN 116263084 A CN116263084 A CN 116263084A
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- gas hydrate
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- sealing cover
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- 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 title claims abstract description 88
- 238000005553 drilling Methods 0.000 title claims abstract description 63
- 238000000034 method Methods 0.000 title claims abstract description 56
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 41
- 238000011161 development Methods 0.000 title claims abstract description 27
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 91
- 239000007789 gas Substances 0.000 claims abstract description 82
- 238000007789 sealing Methods 0.000 claims abstract description 51
- 239000003345 natural gas Substances 0.000 claims abstract description 15
- 238000004873 anchoring Methods 0.000 claims description 64
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 38
- 238000003860 storage Methods 0.000 claims description 32
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 26
- 239000010410 layer Substances 0.000 claims description 23
- 239000001569 carbon dioxide Substances 0.000 claims description 20
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 20
- 239000004576 sand Substances 0.000 claims description 19
- 238000000926 separation method Methods 0.000 claims description 16
- 208000005156 Dehydration Diseases 0.000 claims description 14
- 238000006297 dehydration reaction Methods 0.000 claims description 14
- 230000008569 process Effects 0.000 claims description 14
- 239000013535 sea water Substances 0.000 claims description 14
- 230000018044 dehydration Effects 0.000 claims description 13
- 239000000203 mixture Substances 0.000 claims description 11
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims description 9
- 239000013049 sediment Substances 0.000 claims description 9
- 238000010276 construction Methods 0.000 claims description 8
- 239000011248 coating agent Substances 0.000 claims description 7
- 238000000576 coating method Methods 0.000 claims description 7
- 239000012528 membrane Substances 0.000 claims description 6
- 239000011247 coating layer Substances 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 3
- 230000036571 hydration Effects 0.000 claims description 3
- 238000006703 hydration reaction Methods 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 2
- 238000005086 pumping Methods 0.000 claims description 2
- 238000006073 displacement reaction Methods 0.000 abstract description 11
- 238000011549 displacement method Methods 0.000 abstract description 8
- 230000002349 favourable effect Effects 0.000 abstract 1
- 230000009286 beneficial effect Effects 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 238000006467 substitution reaction Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 4
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 230000003628 erosive effect Effects 0.000 description 3
- 238000005065 mining Methods 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 238000005253 cladding Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 150000004677 hydrates Chemical class 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- -1 natural gas hydrates Chemical class 0.000 description 1
- 239000008239 natural water Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
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
- E21B43/01—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells specially adapted for obtaining from underwater installations
-
- 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
- E21B41/00—Equipment or details not covered by groups E21B15/00 - E21B40/00
- E21B41/0099—Equipment or details not covered by groups E21B15/00 - E21B40/00 specially adapted for drilling for or production of natural hydrate or clathrate gas reservoirs; Drilling through or monitoring of formations containing gas hydrates or clathrates
-
- 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
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/164—Injecting CO2 or carbonated water
-
- 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
- E21B43/34—Arrangements for separating materials produced by the well
- E21B43/36—Underwater separating arrangements
-
- 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
- E21B43/34—Arrangements for separating materials produced by the well
- E21B43/40—Separation associated with re-injection of separated materials
-
- 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
- E21B7/00—Special methods or apparatus for drilling
- E21B7/18—Drilling by liquid or gas jets, with or without entrained pellets
- E21B7/185—Drilling by liquid or gas jets, with or without entrained pellets underwater
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
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Abstract
The invention provides a drilling and production system and method for offshore natural gas hydrate development, and belongs to the technical field of hydrate resource development. The system comprises: ground equipment and underwater equipment; the underwater apparatus includes: the device comprises a sleeve, an oil pipe and a sealing cover; the upper ends of the sleeve, the oil pipe and the sealing cover are respectively connected with ground equipment; the oil pipe passes through the inner cavity of the sleeve, and the sleeve passes through the inner cavity of the sealing cover; a gas lift valve is disposed in the annulus between the casing and the cover. The inventionIncreasing CO using gas drilling techniques 2 The displacement area of the displacement reaction is favorable for further increasing CO 2 Is effective to increase CO 2 The exploitation efficiency of the displacement method effectively solves the production risks of pit shaft and reservoir collapse, buried exploitation equipment and the like which are easily caused by the conventional exploitation method of the natural gas hydrate, and also solves the problem of environment pollution caused by the escape of the natural gas decomposed from the natural gas hydrate.
Description
Technical Field
The invention belongs to the technical field of hydrate resource development, in particular relates to a drilling and production system and method for offshore natural gas hydrate development, and particularly relates to a drilling and production system and method based on CO (carbon monoxide) 2 Gas drilling technique and CO 2 Drilling and production method and system for natural gas hydrate by displacement method.
Background
Natural gas hydrate is a novel energy source with high efficiency and environmental protection, related researches on the natural gas hydrate are carried out in various countries at present, and along with the continuous deep researches, a series of problems, such as low exploitation efficiency, secondary generation of the hydrate, sand production and the like, of the natural gas hydrate are found in the exploitation process, and various exploitation modes are proposed aiming at various problems, wherein CO 2 The displacement method not only can utilize CO to the natural gas hydrate 2 Is displaced and can be used for CO 2 The method has the advantages that the method seals the seabed in a hydrate mode, simultaneously maintains the skeleton structure of the seabed to be stable, prevents the production risks of pit shaft and reservoir collapse, buried exploitation equipment and the like, and has great prospect.
Chinese patent publication CN111119799A discloses a natural gas hydrate exploitation device and method, which adopts a technical means of combining screw pump lifting and solid-liquid-gas separation to jointly lift a natural gas, water and superfine sand mixture, and then separate and store the mixture to realize the exploitation of natural gas hydrate without sand prevention; has the characteristics of simple structure, convenient operation and capacity improvement.
The Chinese patent publication CN108086959A discloses a water flow erosion method ocean natural gas hydrate exploitation method, which aims at the defects of the existing natural gas hydrate exploitation technology, and provides the water flow erosion method ocean natural gas hydrate exploitation technology based on the influence of water flow on the stability of the hydrate, and on the balance of hydrate phases, the water flow method ocean natural gas hydrate exploitation technology is provided by utilizing the decomposition of the hydrate caused by the chemical potential difference between the hydrate phase and the environmental water phase caused by the water flow process and the promotion effect of the water flow on the heat and mass transfer in a reservoir. By utilizing the displacement effect of the water flowing process, the efficient collection of the produced natural gas is realized. The invention provides various combined methods such as a water flow erosion method, a depressurization exploitation method, a heat injection exploitation method and the like.
The Chinese patent publication CN108278100A discloses a natural gas hydrate exploitation gas production method and system, which utilizes the gas lifting effect of methane gas released by decomposing natural gas hydrate to convey a gas-water mixture at the bottom of an exploitation well to a sea surface platform through a marine riser, thereby realizing the controllable self-injection exploitation of the marine natural gas hydrate.
Chinese patent publication CN109915084a discloses a deep water natural gas hydrate exploitation system and a deep water natural gas hydrate exploitation method, the system comprising: the drilling and production platform can be arranged in shallow water; and the deep water natural gas hydrate exploitation system provided by the embodiment of the invention has the advantages of high yield, low construction cost and low risk.
However, the existing CO 2 The displacement method has various defects, the main problems are that the displacement rate of the method is not high, the exploitation efficiency is low, and therefore, the method is highly demanded in CO 2 The substitution rate is improved and the exploitation mode of the exploitation efficiency is increased on the basis of the substitution method to solve the serious problems faced in the exploitation of natural gas hydrate.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provide a drilling and production system and method for offshore natural gas hydrate development based on CO 2 Gas drilling technique and CO 2 Substitution method for developing offshore natural gas hydrate and overcoming CO 2 The exploitation problem of low displacement efficiency of the displacement method.
The invention is realized by the following technical scheme:
in a first aspect of the invention, there is provided a drilling and production system for offshore natural gas hydrate development, the system comprising: ground equipment and underwater equipment;
the underwater apparatus includes: the device comprises a sleeve, an oil pipe and a sealing cover; the upper ends of the sleeve, the oil pipe and the sealing cover are respectively connected with ground equipment;
the oil pipe passes through the inner cavity of the sleeve, and the sleeve passes through the inner cavity of the sealing cover;
a gas lift valve is disposed in the annulus between the casing and the cover.
The invention further improves that:
the sealing cover is of an inverted funnel-shaped structure and comprises a communicating pipe and a conical shell;
the small diameter end of the conical shell is positioned above the large diameter end, and the large diameter end is an open end; the diameter of the small diameter end is smaller than that of the large diameter end, and a central through hole is formed in the small diameter end and is communicated with the lower end of the communicating pipe;
the conical shell is provided with a plurality of holes, and a pressure relief valve, a pressure monitor and a drainage pump are respectively arranged in the holes;
the cable is arranged outside the sealing cover, extends to the conical shell along the outer wall of the communicating pipe, and supplies power for the pressure monitor and the drainage pump.
The invention further improves that:
a plurality of anchoring devices uniformly distributed on the circumference are arranged at the edge of the large-diameter end of the conical shell;
each of the anchoring devices includes: a large head end, a long anchoring rod and a short anchoring rod;
the long anchoring rod and the short anchoring rod are of rod-shaped structures with sharp ends at the lower ends, the length of the long anchoring rod is longer than that of the short anchoring rod, and the long anchoring rod and the short anchoring rod are arranged in parallel and are perpendicular to the big head end; the upper ends of the long anchoring rod and the short anchoring rod are fixedly connected with the lower surface of the big head end.
Preferably, two drainage pumps are arranged on the conical shell of the sealing cover, the two drainage pumps are symmetrically arranged above the anchoring device, and a pressure monitor and a pressure relief valve are arranged above one of the drainage pumps.
The invention further improves that:
the gas lift valve and a plurality of packers are arranged in an annulus between the communicating pipe and the casing;
the gas lift valve is mounted above the topmost packer.
The invention further improves that:
the ground device comprises: the second booster pump group and the methane storage tank are connected with the second booster pump group through pipelines;
the annular space between the communicating pipe and the sleeve is connected with the second booster pump group through a pipeline, and a flat valve is arranged on the pipeline.
The invention further improves that:
the ground device comprises: the first booster pump group is respectively connected with the carbon dioxide gas storage tank and the nitrogen gas storage tank through pipelines;
the upper end of the oil pipe is connected with a rotary blowout preventer, and the rotary blowout preventer is connected with a first booster pump group through a pipeline;
and flat valves are respectively arranged on the pipeline between the first booster pump group and the rotary blowout preventer, the pipeline between the carbon dioxide gas storage tank and the first booster pump group and the pipeline between the nitrogen gas storage tank and the first booster pump group.
The invention further improves that:
the above-ground apparatus includes: the sand removal module and the dehydration separation module;
the upper end of the sleeve is connected with the drilling double-way, the drilling double-way is connected with one end of the sand removal module, and the other end of the sand removal module is connected with the dehydration separation module.
In a second aspect of the invention, there is provided a method of offshore natural gas hydrate development using the system described above, the method comprising:
(1) The seawater in the sealing cover is put in and discharged out;
(2) A tubular column structure of an oil sleeve is put in;
(3) Drilling construction;
(4) Drilling construction of a natural gas hydrate reservoir;
(5) Natural gas hydrate exploitation;
(6) Carrying out post-treatment on a platform;
(7) Backfilling silt;
(8) And (5) recovering the sealing cover.
The invention further improves that:
the operation of step (1) comprises:
pressing the sealing cover into the natural gas hydrate reservoir, and respectively anchoring the short anchoring rod and the long anchoring rod on the anchoring device into an upper coating layer and a lower coating layer of the natural gas hydrate reservoir;
and opening the draining pump to drain the sea water inside the sealing cover.
The invention further improves that:
the operation of step (3) comprises:
when the drill bit reaches the upper coating, a flat valve at the nitrogen storage tank is opened, the high-pressure nitrogen is pumped into the oil pipe by utilizing the first booster pump group, high-pressure nitrogen is ejected from the drill bit, the natural gas hydrate upper coating is crushed, the casing pipe gradually goes into the drill bit in the process, when the drill bit reaches the upper part of the natural gas hydrate layer, the drill bit is stopped firstly, then the flat valve at the nitrogen storage tank is closed, the casing pipe is rotated, and the packer arranged outside the casing pipe is used for setting.
The invention further improves that:
the operation of step (4) comprises:
opening a flat valve at the carbon dioxide storage tank, pumping high-pressure carbon dioxide gas into the oil pipe, and continuing drilling downwards;
when drilling to the free gas-water layer, stopping drilling, and continuously injecting carbon dioxide gas into the natural gas hydration layer through the drill bit.
The invention further improves that:
the operation of step (5) comprises:
in the process of continuously injecting carbon dioxide gas into the natural gas hydrate layer through the drill bit, after the second booster pump is used for boosting the pressure of methane in the methane storage tank, the methane is injected into an annulus between the communicating pipe and the sleeve, the gas lift valve is opened, methane in the annulus enters the oil collar through the gas lift valve, and is mixed with carbon dioxide, natural gas and partial free water in the oil collar to form a mixture, and the mixture is lifted through the oil collar annulus.
The invention further improves that:
the operation of step (6) comprises:
and (3) carrying out sand filtering treatment and membrane separation dehydration treatment on the mixture lifted by the oil sleeve annulus to obtain methane gas.
The invention further improves that:
the operation of step (7) comprises:
lifting an oil pipe, injecting the produced sediment and seawater into a well hole through a casing pipe, and realizing backfilling of the sediment at a production layer;
and rotating the sleeve, unsealing the packer and taking out the sleeve.
Compared with the prior art, the invention has the beneficial effects that:
the invention is suitable for the development of offshore natural gas hydrate, and CO is increased by utilizing the gas drilling technology 2 The displacement area of the displacement reaction is utilized, and the small molecular gas N is utilized for drilling the upper coating 2 Is beneficial to further increase CO 2 Is effective to increase CO 2 The exploitation efficiency of the displacement method, and the silt backfilling mode of the invention effectively solves the problems of pit shaft and reservoir collapse and buried exploitation equipment which are easily caused by the conventional natural gas hydrate exploitation methodAnd the production risk, and the design of the sealing cover also solves the problem of environment pollution caused by the escape of the natural gas decomposed by the natural gas hydrate.
Drawings
FIG. 1 is a schematic diagram of the configuration of an underwater apparatus in the system of the present invention;
fig. 2 is a schematic diagram of the structure of a ground device in the system of the present invention.
The drawings are marked with the following description:
1-offshore platform, 2-casing, 3-gas lift valve, 4-cable, 5-packer, 6-bonnet, 7-pressure relief valve, 8-pressure monitor, 9-drain pump, 10-anchoring device, 11-tubing, 12-drill collar, 13-bit sub, 14-bit, 15-overburden, 16-natural gas hydrate layer, 17-free gas water layer, 18-underburden, 19-rotary blowout preventer control assembly, 20-rotary blowout preventer, 21-annular blowout preventer top, 22-annular blowout preventer, 23-semi-seal ram, 24-double ram, 25-blind ram, 26-drilling double pass, 27-plate valve, 28-first booster pump set, 29-carbon dioxide gas storage tank, 30-nitrogen gas storage tank, 31-methane gas storage tank, 32-second booster pump set, 33-sand removal module, 34-dehydration separation module.
Detailed Description
The invention is described in further detail below with reference to the attached drawing figures:
as shown in fig. 1 and 2, the drilling and production system for offshore natural gas hydrate development provided by the invention comprises: ground equipment and underwater equipment are specifically as follows:
as shown in fig. 2, the ground device includes: the rotary blowout preventer control assembly 19, the rotary blowout preventer 20, the annular blowout preventer bonnet 21, the annular blowout preventer 22, the half ram 23, the double ram blowout preventer 24, the full ram 25, and the drilling bi-pass 26, which are all existing products, are connected in sequence from top to bottom, and are not described in detail herein.
The underwater apparatus includes: casing 2, tubing 11, gas lift valve 3, cable 4, packer 5, cover 6, pressure relief valve 7, pressure monitor 8, drain pump 9, anchoring device 10, drill collar 12, bit sub 13, drill bit 14. The drill bit 14 is connected with the drill bit joint 13, the drill bit joint 13 is connected with the drill collar 12, and the drill collar 12 is connected with the lower end of the oil pipe 11.
The surface equipment is installed on an offshore platform 1, and the offshore platform 1 floats on the sea surface. The high-pressure gas reaches the drill bit 14 through the oil pipe 11 for jet crushing operation, and the produced methane gas is recovered through the annulus between the oil pipe 11 and the casing 2. The upper end of the oil pipe 11 is suspended by a derrick at the offshore platform 1, the lower end of the oil pipe 11 sequentially passes through a rotary blowout preventer control assembly 19, a rotary blowout preventer 20, an annular blowout preventer top cover 21, an annular blowout preventer 22, a half-seal flashboard 23, a double flashboard blowout preventer 24, a full-seal flashboard 25 and a drilling double-pass 26 in fig. 2, passes through the inner cavity of the casing 2, and then is connected with the drill collar 12, and an opening is arranged at the position of the oil pipe 11 in the rotary blowout preventer 20, the opening is connected with a first booster pump group through the rotary blowout preventer 20, and the first booster pump group is connected with a carbon dioxide gas storage tank. These are all the equipment that current drilling and production system had, and its structure and connected mode are not repeated.
The invention adds a gas lift valve 3, a packer 5, a cable 4, a sealing cover 6, a pressure relief valve 7, a pressure monitor 8, a drainage pump 9, an anchoring device 10, a nitrogen gas storage tank, a second booster pump group, a methane storage tank and the like to the existing drilling and production system. After the sealing cover 6 is anchored by the anchoring device 10, the casing 2 is put into the sealing cover 6, the oil pipe 11 is positioned inside the casing 2, the annulus between the oil pipe 11 and the casing 2 is an oil sleeve annulus, the gas lift valve 3 and the packer 5 are sequentially arranged outside the casing 2 from top to bottom, and when the casing 2 is rotated to the natural gas hydrate layer 16, the packer 5 is set, and the casing 2 is fixed.
An example of the system is as follows:
[ embodiment one ]
The sealing cover 6 is of an inverted funnel-shaped structure and comprises a communicating pipe and a conical shell connected with the lower end of the communicating pipe, the small-diameter end of the conical shell is located above the large-diameter end, and the large-diameter end is an open end. The diameter of the small diameter end is smaller than that of the large diameter end, and a central through hole is formed in the small diameter end and is communicated with the lower end of the communicating pipe.
The conical shell is provided with a plurality of holes, and a pressure relief valve 7, a pressure monitor 8 and a drainage pump 9 are respectively arranged in the holes. A plurality of anchoring devices 10 are provided at the edge of the large diameter end of the cone-shaped housing. A cable 4 is arranged outside the sealing cover 6, and the cable 4 extends to the conical shell along the outer wall of the communicating pipe to supply power for the pressure monitor 8, the drainage pump 9 and the like.
The upper end of the communicating pipe of the sealing cover 6 is sequentially connected with a fixing device (the existing device is not shown in fig. 1 and 2) on the offshore platform, and is communicated with a methane gas storage tank through a second booster pump group, so that a gas lift process can be performed in an annulus of the communicating pipe and the sleeve by utilizing methane gas. The lower end of the sleeve 2 sequentially passes through the communicating pipe and the conical shell and is inserted into the sea floor.
Preferably, two drainage pumps 9 are arranged on the conical shell of the sealing cover 6, the two drainage pumps 9 are arranged above the anchoring device 10, the two drainage pumps 9 are symmetrically arranged, 1 group of pressure monitors 8 and pressure relief valves 7 are arranged above one of the drainage pumps 9, and the cable 4 is connected with the pressure monitors 8 and the drainage pumps 9. The drain pump 9 is capable of communicating sea water between the inside and the outside of the cover 6, the pressure relief valve 7 is for relieving pressure inside the cover 6, and the pressure monitor 8 is for monitoring pressure inside the cover 6.
The gas lift valve 3 and the packer 5 are both arranged in an annulus between a communicating pipe of the sealing cover 6 and the casing 2, the casing 2 can be rotated on the offshore platform 1 for setting, and the packer 5 can be additionally arranged in the annulus according to different drilling speeds, so that the stability of the casing 2 is improved. Specifically, a gas lift valve 3 is installed above a topmost packer 5 on the casing 2, natural gas (methane) with certain pressure can be injected into an annulus between the communicating pipe and the casing 2 through the offshore platform 1 to open the gas lift valve 3, so that the pressure gradient of the air mixed gas of the oil collar is reduced, and the lifting efficiency is improved.
The pressure monitor, the pressure relief valve, the anchoring device and the drainage pump arranged on the sealing cover 6 can perform underwater cooperative operation.
[ example two ]
The number of the anchoring devices 10 is 4, the anchoring devices are uniformly arranged around the bottom of the sealing cover 6, for example, the anchoring devices can be fixedly connected at the edge of the large-diameter end of the conical shell in a welding mode at the outer edge of the sealing cover, and a plurality of the anchoring devices 10 are uniformly distributed on the circumference of the bottom end edge of the sealing cover 6.
Specifically, each anchoring device 10 includes a big end, and a long anchoring rod and a short anchoring rod connected with the big end, the long anchoring rod and the short anchoring rod are rod-shaped structures with sharp ends at the lower ends, the length of the long anchoring rod is greater than that of the short anchoring rod, the long anchoring rod and the short anchoring rod are arranged in parallel, the long anchoring rod and the short anchoring rod are perpendicular to the big end, the upper ends of the long anchoring rod and the short anchoring rod are fixedly connected with the lower surface of the big end, and the big end is fixedly connected with the edge of the lower end of the sealing cover 6.
When the closure 6 is lowered, the lower end of the short anchoring rod of the anchoring device 10 at the lower end of the closure 6 is able to anchor into the overburden 15 of the natural gas hydrate reservoir and the lower end of the long anchoring rod is able to anchor into the underburden 18 of the natural gas hydrate reservoir.
[ example III ]
Further, the above-ground apparatus further comprises: the first booster pump group 28 is connected with a carbon dioxide gas storage tank 29 and a nitrogen gas storage tank 30 through pipelines respectively. Meanwhile, the upper end of the oil pipe 11 is connected with the rotary blowout preventer 20, and the rotary blowout preventer 20 is connected with the outlet end of the first booster pump group through a pipeline.
[ example IV ]
The above-ground apparatus further comprises: the second booster pump unit 32 and the methane storage tank 31 connected with the second booster pump unit are communicated with the annular space between the communicating pipe of the sealing cover 6 and the sleeve 2 through a pipeline, the annular space is utilized for carrying out gas lift auxiliary lifting, and the pipeline is provided with a flat valve 27.
[ example five ]
The above-ground apparatus further comprises: the sand removal module 33 and the dehydration separation module 34 are connected in sequence. The upper end of the sleeve 2 is connected with a drilling double-pass 26, the drilling double-pass 26 is connected with one end of a sand removal module, and thus an annulus between the oil pipe 11 and the sleeve 2 is communicated with the sand removal module, and the other end of the sand removal module is connected with a dehydration separation module. Methane extracted from the seabed enters a sand removal module through an oil sleeve annulus, enters a dehydration separation module after being treated by the sand removal module, and obtains methane gas, carbon dioxide and water after passing through the dehydration separation module, thereby realizing the development of offshore natural gas hydrate.
The invention also provides a method for developing the offshore natural gas hydrate by utilizing the system, which integrates the small molecular gas mixed CO 2 The advantages of the displacement method, the depressurization method and the gas lift method overcome the defects of the original single mining method.
An example of the method is as follows:
[ example six ]
The method comprises the following steps:
(1) Into the cover and out of the cover interior sea water: the cover 6 is lowered from the offshore platform 1, the cover 6 is pressed into the natural gas hydrate reservoir (the cover 6 can be pressed down by using a hydraulic pile hammer freely suspended on an existing floating crane, and the existing device is not described herein), an anchoring device 10 on the cover 6 is used for respectively anchoring an upper coating 15 and a lower layer 18 of the natural gas hydrate reservoir, and after anchoring, the drainage pump 9 on the cover 6 is opened to discharge seawater in the cover 6.
(2) And (3) lowering an oil casing string structure: after the seawater in the sealing cover 6 is discharged (when the numerical change of the pressure monitor 8 mounted on the sealing cover tends to be stable, the seawater in the sealing cover can be judged to be discharged), the casing pipe 2 with the packer 5 and the gas lift valve 3 outside is put into the sealing cover 6, the oil pipe 11 is arranged in the casing pipe 2, the drill collar 12, the drill bit joint 13 and the drill bit 14 are sequentially connected to the lower part of the oil pipe 11, the packer 5 and the gas lift valve 3 are positioned in an annular space between the oil pipe and a communicating pipe of the sealing cover, and the lower ends of the casing pipe and the oil pipe extend to the lower part of the sealing cover.
The purpose of discharging seawater by using the cover is as follows:
1. when the natural gas hydrate is mined, as the natural gas hydrate in the reservoir is decomposed, part of gas overflows into the sealing cover through the upper coating layer, if the gas is not drained, a pressure relief valve arranged on the sealing cover can slow down due to the pressure relief efficiency of a liquid phase, the pressure can not be relieved in time, and when the pressure in the sealing cover is increased to a certain value and the pressure is not relieved in time, mining accidents are easily caused;
2. methane gas escaping from the reservoir, in combination with water, will dramatically increase the corrosion efficiency of the closure, thus reducing the corrosion of the closure after the seawater is discharged.
(3) Drilling construction: when the drill bit 14 reaches the upper cladding 15 (before the exploitation construction operation is performed, the submarine stratum of the exploitation area needs to be detected to obtain various data of each horizon, such as the stratum depth, and the like, according to the data, the drill bit is combined with the depth of the drill bit to know which horizon is drilled into, the method for judging whether to drill into a certain horizon is the same as the method in the following steps), a flat valve 27 positioned at a nitrogen storage tank on the offshore platform 1 is opened, and the high-pressure N is supplied by a first booster pump group of the offshore platform 1 2 The air pump is put into the oil pipe 11, the high pressure N 2 Gas is sprayed out from a nozzle at the drill bit 14 to crush the natural gas hydrate coating 15, in the process, the casing 2 gradually enters while drilling, when drilling to the upper part of the natural gas hydrate layer 16, the drilling is stopped firstly, then a flat valve 27 at the nitrogen gas storage tank is closed, the casing 2 is rotated, and the casing is set by using a packer 5 arranged outside the casing.
(4) Drilling construction of natural gas hydrate reservoirs: the flat valve 27 at the carbon dioxide storage tank is opened to discharge high-pressure CO 2 The gas is pumped into the oil pipe 11, the drilling operation is continued downwards, when the free gas water layer 17 is drilled, the drilling is stopped, and meanwhile, CO is continuously injected into the natural gas hydration layer 16 through the nozzle at the drill bit 14 2 And (3) gas.
(5) Natural gas hydrate recovery: as offshore platform 1 continues to inject CO into natural gas hydrate layer 16 through drill bit 14 2 Gas, and CO 2 The formation conditions of the hydrate and the natural gas hydrate have a certain temperature and pressure difference, so the CO 2 Methane gas in natural gas hydrate is replacedVolumetric and CO production 2 In the process of the hydrate, methane in a methane storage tank is pressurized by a second booster pump and then injected into an annulus between a communicating pipe of a sealing cover 6 and a sleeve 2, and as a packer 5 is arranged in the annulus between the communicating pipe and the sleeve, the pressure in the annulus is continuously increased in the process of injecting the methane, and when the pressure in the annulus is increased to a certain degree, a gas lift valve 3 positioned outside the sleeve 2 is opened, and methane in the annulus enters the oil collar through the gas lift valve 3 and is in air with CO in the oil collar 2 Natural gas and a portion of the free water are mixed to form a mixture that is lifted through the oil jacket annulus.
By injecting high pressure methane into the annulus between the communication pipe and the sleeve, the pressure gradient in the oil collar is reduced (because the gas lift valve is arranged outside the sleeve and is communicated with the annulus between the communication pipe of the sealing cover 6 and the sleeve, because methane gas injected by the platform and extracted fluid are mutually mixed, the density of the extracted fluid is reduced, thereby reducing the pressure gradient and improving the lifting efficiency), the oil collar is beneficial to increasing the extraction efficiency, and meanwhile, the pressure in the oil collar is gradually reduced at the position of the natural gas hydrate layer 16 due to the fact that the pressure in the oil collar is smaller than the reservoir pressure of the natural gas hydrate layer 16, the extraction efficiency is improved (because the natural gas hydrate can be formed under the environment of low temperature and high pressure, the pressure and the lifting temperature are both beneficial to decomposing the natural gas hydrate).
(6) And (3) carrying out post-treatment on a platform: firstly, filtering sand from the mixture (including mixed gas, free water and the like) lifted by an oil sleeve annulus, enabling the processed mixed gas and free water to enter a dehydration separation module, performing membrane separation dehydration in the dehydration separation module, and when the gas flows through the membrane surface, enabling the CO contained in the gas to flow through the membrane surface 2 And water can be removed by preferentially penetrating through the separation membrane to obtain methane gas, and finally the whole natural gas hydrate exploitation process is completed.
(7) And (3) backfilling sediment: at the end of production, the tubing 11 with the drill bit 14 is lifted up, due to the CO produced 2 The hydrate has been partially filled into the bottom layer, but is required to maintain the strength of the subsea skeleton structureThe method comprises the steps of injecting the produced sediment and seawater into a well hole through a casing 2 (equipment used for sediment backfilling is existing equipment and is not shown in fig. 2), forming certain overpressure at a well bottom to realize backfilling of the sediment at a production layer, rotating the casing 2, deblocking a packer 5, dragging a lower tubular column upwards slowly, lifting the casing out, and completing the whole sediment backfilling process;
(8) And (3) recovering the sealing cover: after the silt is backfilled, the offshore platform 1 lifts the anchored cap 6 and recovers it.
The invention relates to a mining mode suitable for offshore natural gas hydrate drilling and production, which utilizes a gas drilling technology to increase CO 2 Area of displacement reaction (compared to conventional CO using gas drilling techniques 2 Direct CO injection in substitution process 2 Is more beneficial to CO 2 Diffusion in natural gas reservoirs can be used for substitution reaction with more natural gas hydrates to generate CO 2 Hydrates displace methane gas, thus increasing CO 2 The displacement area of the displacement reaction), and utilizes a small molecular gas (N) due to the drilling of the upper cladding layer 2 ) Is beneficial to further increase CO 2 Is compared with single CO injection (research shows that 2 The gas undergoes displacement reaction to make CO 2 The gas and the micromolecular gas are mixed and then injected into the reactor, so that the replacement efficiency is higher, the effect is better, and the CO is effectively increased 2 The exploitation efficiency of the displacement method is gradually reduced through the oil sleeve annulus, the exploitation efficiency is improved again, and the decomposition of the natural gas hydrate is promoted, and the technology utilizes CO 2 The hydrate and silt backfilling mode effectively solves the production risks of pit shaft and reservoir collapse, buried exploitation equipment and the like which are easily caused by the conventional exploitation method of the natural gas hydrate, and the design of the sealing cover also solves the problem that the natural gas decomposed by the natural gas hydrate escapes to pollute the environment.
The invention solves the problems of natural gas hydrate CO 2 Low substitution rate, low production efficiency, collapse of well bore and reservoir and production processThe natural gas leakage and other problems have important significance for the exploitation of offshore natural gas hydrate.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "connected," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances. The specific connection modes of all parts in the invention adopt the conventional means of mature bolts, rivets, welding and the like in the prior art, the machinery, the parts and the equipment adopt the conventional model in the prior art, and the connection adopts the conventional connection modes in the prior art, so the details are not described here
In the description of the present invention, unless otherwise indicated, the terms "upper," "lower," "left," "right," "inner," "outer," and the like are used for convenience in describing the present invention and simplifying the description based on the orientation or positional relationship shown in the drawings, and do not denote or imply that the devices or elements in question must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.
Finally, it should be noted that the above-mentioned technical solution is only one embodiment of the present invention, and various modifications and variations can be easily made by those skilled in the art based on the application methods and principles disclosed in the present invention, and are not limited to the methods described in the above-mentioned specific embodiments of the present invention, therefore, the foregoing description is only preferred, and not meant to be limiting.
Claims (15)
1. The drilling and production system for the development of the offshore natural gas hydrate is characterized in that: the system comprises: ground equipment and underwater equipment;
the underwater apparatus includes: the device comprises a sleeve, an oil pipe and a sealing cover; the upper ends of the sleeve, the oil pipe and the sealing cover are respectively connected with ground equipment;
the oil pipe passes through the inner cavity of the sleeve, and the sleeve passes through the inner cavity of the sealing cover;
a gas lift valve is disposed in the annulus between the casing and the cover.
2. The offshore natural gas hydrate development drilling and production system of claim 1, wherein: the sealing cover is of an inverted funnel-shaped structure and comprises a communicating pipe and a conical shell;
the small diameter end of the conical shell is positioned above the large diameter end, and the large diameter end is an open end; the diameter of the small diameter end is smaller than that of the large diameter end, and a central through hole is formed in the small diameter end and is communicated with the lower end of the communicating pipe;
the conical shell is provided with a plurality of holes, and a pressure relief valve, a pressure monitor and a drainage pump are respectively arranged in the holes;
the cable is arranged outside the sealing cover, extends to the conical shell along the outer wall of the communicating pipe, and supplies power for the pressure monitor and the drainage pump.
3. The offshore natural gas hydrate development drilling and production system of claim 2, wherein: a plurality of anchoring devices uniformly distributed on the circumference are arranged at the edge of the large-diameter end of the conical shell;
each of the anchoring devices includes: a large head end, a long anchoring rod and a short anchoring rod;
the long anchoring rod and the short anchoring rod are rod-shaped structures with sharp ends at the lower ends; the length of the long anchoring rod is longer than that of the short anchoring rod, and the long anchoring rod and the short anchoring rod are arranged in parallel and are perpendicular to the big head end; the upper ends of the long anchoring rod and the short anchoring rod are fixedly connected with the lower surface of the big head end.
4. A drilling and production system for offshore natural gas hydrate development according to claim 3, wherein: two drainage pumps are arranged on the conical shell of the sealing cover and are symmetrically arranged above the anchoring device, and a pressure monitor and a pressure relief valve are arranged above one of the drainage pumps.
5. A drilling and production system for offshore natural gas hydrate development according to claim 3, wherein: the gas lift valve and a plurality of packers are arranged in an annulus between the communicating pipe and the casing;
the gas lift valve is mounted above the topmost packer.
6. The offshore natural gas hydrate development drilling and production system of claim 5, wherein: the ground device comprises: the second booster pump group and the methane storage tank are connected with the second booster pump group through pipelines;
the annular space between the communicating pipe and the sleeve is connected with the second booster pump group through a pipeline, and a flat valve is arranged on the pipeline.
7. The offshore natural gas hydrate development drilling and production system of claim 6, wherein: the ground device comprises: the first booster pump group is respectively connected with the carbon dioxide gas storage tank and the nitrogen gas storage tank through pipelines;
the upper end of the oil pipe is connected with a rotary blowout preventer, and the rotary blowout preventer is connected with a first booster pump group through a pipeline;
and flat valves are respectively arranged on the pipeline between the first booster pump group and the rotary blowout preventer, the pipeline between the carbon dioxide gas storage tank and the first booster pump group and the pipeline between the nitrogen gas storage tank and the first booster pump group.
8. The offshore natural gas hydrate development drilling and production system of claim 7, wherein: the above-ground apparatus includes: the sand removal module and the dehydration separation module;
the upper end of the sleeve is connected with the drilling double-way, the drilling double-way is connected with one end of the sand removal module, and the other end of the sand removal module is connected with the dehydration separation module.
9. A drilling and production method for offshore natural gas hydrate development is characterized by comprising the following steps of: the method comprises the following steps:
(1) The seawater in the sealing cover is put in and discharged out;
(2) A tubular column structure of an oil sleeve is put in;
(3) Drilling construction;
(4) Drilling construction of a natural gas hydrate reservoir;
(5) Natural gas hydrate exploitation;
(6) Carrying out post-treatment on a platform;
(7) Backfilling silt;
(8) And (5) recovering the sealing cover.
10. The drilling and production method for offshore natural gas hydrate development according to claim 9, wherein: the operation of step (1) comprises:
pressing the sealing cover into the natural gas hydrate reservoir, and respectively anchoring the short anchoring rod and the long anchoring rod on the anchoring device into an upper coating layer and a lower coating layer of the natural gas hydrate reservoir;
and opening the draining pump to drain the sea water inside the sealing cover.
11. The drilling and production method for offshore natural gas hydrate development according to claim 9, wherein: the operation of step (3) comprises:
when the drill bit reaches the upper coating, a flat valve at the nitrogen storage tank is opened, the high-pressure nitrogen is pumped into the oil pipe by utilizing the first booster pump group, high-pressure nitrogen is ejected from the drill bit, the natural gas hydrate upper coating is crushed, the casing pipe gradually goes into the drill bit in the process, when the drill bit reaches the upper part of the natural gas hydrate layer, the drill bit is stopped firstly, then the flat valve at the nitrogen storage tank is closed, the casing pipe is rotated, and the packer arranged outside the casing pipe is used for setting.
12. The drilling and production method for offshore natural gas hydrate development according to claim 11, wherein: the operation of step (4) comprises:
opening a flat valve at the carbon dioxide storage tank, pumping high-pressure carbon dioxide gas into the oil pipe, and continuing drilling downwards;
when drilling to the free gas-water layer, stopping drilling, and continuously injecting carbon dioxide gas into the natural gas hydration layer through the drill bit.
13. The drilling and production method for offshore natural gas hydrate development according to claim 12, wherein: the operation of step (5) comprises:
in the process of continuously injecting carbon dioxide gas into the natural gas hydrate layer through the drill bit, after the second booster pump is used for boosting the pressure of methane in the methane storage tank, the methane is injected into an annulus between the communicating pipe and the sleeve, the gas lift valve is opened, methane in the annulus enters the oil collar through the gas lift valve, and is mixed with carbon dioxide, natural gas and partial free water in the oil collar to form a mixture, and the mixture is lifted through the oil collar annulus.
14. The drilling and production method for offshore natural gas hydrate development of claim 13, wherein: the operation of step (6) comprises:
and (3) carrying out sand filtering treatment and membrane separation dehydration treatment on the mixture lifted by the oil sleeve annulus to obtain methane gas.
15. The drilling and production method for offshore natural gas hydrate development according to claim 9, wherein: the operation of step (7) comprises:
lifting an oil pipe, injecting the produced sediment and seawater into a well hole through a casing pipe, and realizing backfilling of the sediment at a production layer;
and rotating the sleeve, unsealing the packer and taking out the sleeve.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114033322A (en) * | 2021-10-14 | 2022-02-11 | 中海石油(中国)有限公司 | Deepwater oil and gas drilling and carbon dioxide utilization and sequestration integrated device and method |
| CN117211739A (en) * | 2023-09-22 | 2023-12-12 | 青岛海洋地质研究所 | Ocean natural gas hydrate normal position planting device |
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2021
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114033322A (en) * | 2021-10-14 | 2022-02-11 | 中海石油(中国)有限公司 | Deepwater oil and gas drilling and carbon dioxide utilization and sequestration integrated device and method |
| CN117211739A (en) * | 2023-09-22 | 2023-12-12 | 青岛海洋地质研究所 | Ocean natural gas hydrate normal position planting device |
| CN117211739B (en) * | 2023-09-22 | 2024-04-09 | 青岛海洋地质研究所 | Ocean natural gas hydrate normal position planting device |
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