CN101376853B - Method and apparatus for simulating gas hydrate accumulation process under one-dimensional condition - Google Patents
Method and apparatus for simulating gas hydrate accumulation process under one-dimensional condition Download PDFInfo
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Abstract
The invention provides a method and a device for simulating the accumulation process of a gas hydrate under a one-dimension condition which mainly simulates the accumulation process of the gas hydrate by forming a hydrate in the inner chamber of an one-dimension high pressure reactor; the inner chamber of the reactor is divided into an upper part, a middle part and a lower part; the middle part is divided into an aquiferous porous medium filling area used for generating the hydrate; the upper part and the lower part are free spaces; the method includes: experiment gases are led into the inner chamber of the reactor from the lower part of the reactor to lead the experiment gases to seep from up to down and pass through the porous medium filling area; the hydrate is generated in the porous medium filling area and the experiment gases not reacted are led out from the upper part of the reactor; the forming speed of the hydrate is detected by detecting the flux change of the gases in the seeping process in the porous medium. The method and device can simulate the two forms of gas migration and water migration formed by the hydrate and can simulate the whole processes of the hydrate from nucleation inducing, gradual forming of the hydrate, the accumulation of the hydrate to trapping.
Description
Technical field
The present invention relates to a kind of gas hydrate particularly method and device of Gas Hydrate Deposition process of simulating under one-dimensional condition, belong to resources domain.
Background technology
Gas hydrate are the white solid matter of seemingly icing shape that formed under the cryogenic high pressure condition by natural G﹠W, are distributed widely in the settling on ocean continental shelf and slope and land permafrost band.Be main because of its gas component mainly with methane, therefore claim again methane hydrate.According to scientist's tentative prediction, the organic carbon in the contained Sweet natural gas of global gas hydrate is 2 times of the contained total organic carbons of fossil oil such as oil, Sweet natural gas and coal, and total resources is about (1.8～2.1) * 10
16m
3There is wide natural gas hydrate resources prospect in China marine site and exclusive economic zone, and preresearch estimates shows, the hydrate in China's the continental slope of the South China Sea and trough settling can satisfy China's energy demand of centuries from now on.The resource exploration of gas hydrate must be based upon hydrate is become to hide on the basis of mechanism and regularity of distribution understanding with evaluation.
There is the scholar to think that the nature hydrate exists dispersion pattern and leakage type two classes (referring to document [1]: Cathles L M, Chen D F.A compositional kinetic model of hydratecrystallization and dissolution.J.Geophys.Res., 2004,109, B08102; Document [2]: Fan's bolt lion, Liu Feng, Chen Duofu. the formation Exploration of Mechanism of ocean gas hydrate. the Sweet natural gas geoscience, 2004,15 (5), 524-530).Wherein, the leakage type hydrate buries shallow, in the seabed, exposure is arranged.And the gas hydrate of occurring in nature mostly are greatly dispersion pattern, after being generated by microorganism or heat effect take methane as main hydrocarbon gas, form on the spot hydrate under suitable Temperature-pressure Conditions, or discharge gas formation hydrate by the saturation water of Upward Migration, or form hydrate by free gas Upward Migration; That is, hydrate formation pattern in following three kinds of oceanic sediments is arranged:
(1) by biogenesis methanogenesis hydrate: in the hydrate stable region, after biogenesis methane generated, under suitable Temperature-pressure Conditions, the water in the settling hole was combined, and formed hydrate, was filled in hole;
(2) water by Upward Migration discharges gas and forms hydrate (water transport moves): in the seabed deep layer, take methane as main gas dissolving in seawater and the state that reaches capacity; Under external influence, the deep layer fluid is migration upwards, and in this process, the reduction of pressure makes the solubleness of gas in seawater reduce, and gas is separated out in seawater, and the gas arrival hydrate stable region of separating out will form hydrate;
(3) form hydrate (fate is moved) by free gas Upward Migration: in the seabed, in settling or earth's surface deep layer discharges many gases, because the density of the density ratio water and sediment of free gas is little, in the hydrate stable region, free gas is with Upward Migration; The gas of Upward Migration might be by impervious settled layer capping, and these capping layers can provide the hole for free gas, and then these gases generate hydrate in the hole.
The at present research that forms of hydrate mainly in the main body phase system, is generally the mixture synthesized hydrate from ice and gas, or from the liquid water of stirring and free gas synthesized hydrate, but can not represent the ocean environment condition.For containing sediment, because settling can't stir, at present in settling in the simulating lab test of the generative process of hydrate, mostly by gas with contain the water sediment Static Contact, slowly generate hydrate.Not only speed is slow to generate like this hydrate, and hydrate is mainly to generate at gas and sedimental intersection, exists than big difference with natural hydrate formation pattern.(the document [3]: Wang Yubin such as Wang Yubin, Fan's bolt lion, put peace into, Liang Deqing, Feng Ziping. Experimental Simulation of Oceanic Leakage Hydrate Formation. Sweet natural gas geoscience, 2007,18,596-600) according to the formation feature of gas hydrate seepage system, set up the Experimental Simulation of Oceanic Leakage Hydrate Formation device, wherein with CO
2Hydrate is example, mainly by the bubbling method air inlet, in layer of sand, the aqueous phase on layer of sand bottom and layer of sand top all has hydrate to generate, with simulation exposed hydrate in seawater.And also seldom report for the simulation take dispersion pattern as main gas hydrate that is in the great majority, for real seabed hundreds of (experimental pressure can reach tens MPa) to the depth of water sub-surface of several kms, take the forming process of methane as main gas hydrate, the fate that not only needs simulating hydrate to form is moved with water transport and is moved two kinds of forms, need simultaneously simulating hydrate from nucleation induce, hydrate forms gradually, hydrate become to be hidden until the whole process of trap, current research also lacks effective experimental simulation means.Relevant Gas Hydrate Deposition research on mechanism is also very insufficient both at home and abroad at present.
Summary of the invention
Main purpose of the present invention is to provide a kind of particularly method of Gas Hydrate Deposition process of analog gas hydrate, is mainly the self-assembling formation process of gas hydrate under the simulation one-dimensional condition.
Another object of the present invention is to provide the particularly device of Gas Hydrate Deposition process of a kind of analog gas hydrate, be used for the forming process of gas hydrate under the simulation one-dimensional condition.
For the analog gas hydrate self-assembling formation process of gas hydrate particularly, the present invention be mainly adopt by mensurated gas composition in porous medium in flow event the variation of flow determine hydrate formation speed, the forming process of simulating hydrate.
On the one hand, the invention provides a kind of method of simulating gas hydrate accumulation process under one-dimensional condition, the method is to utilize at one dimension high-pressure reactor inner room formation hydrate to come the analog gas hydrate to become the Tibetan process, described reactor inner room is divided into upper, middle, and lower part, middle portion is for being used for generating the moisture porous medium fill area of hydrate, and the upper and lower part is divided into freeboard; The method comprises:
Experimental gas is introduced the reactor inner room from reactor lower part, make experimental gas from bottom to top seepage flow through the porous medium fill area, generate hydrate in the porous medium fill area, and unreacted experimental gas is drawn from reactor top.
In the method for the present invention, can determine that hydrate forms speed by mensurated gas composition fluctuations in discharge in flow event in porous medium.
Analog gas hydrate of the present invention becomes the method for Tibetan process, and the fate that can simulating hydrate forms is moved form, namely simulates free gas to the plenum system of porous medium layer diffusion or infiltration; The water transport that also can simulating hydrate forms moves form, namely simulates by the saturated aqueous solution of experimental gas and migrates to the plenum system that discharges gas in porous medium.
According to a specific embodiments of the present invention, method of the present invention is to simulate by the process of free gas to the plenum system form hydrate of porous medium layer diffusion or infiltration, and described method comprises:
The experimental gas of dissociating is filled with reactor, make reactor easy on and off space gaseous tension reach experimental pressure, begin experiment, make experimental gas enter reactor inner room, bottom-up seepage flow through porous medium, drawn from reactor top again from reactor lower part;
Keep the upper and lower freeboard gaseous tension of reactor and pressure reduction constant in the single experiment process, in the experiments of measuring process, the flow of gas turnover reactor over time.
In the method, can pass in and out according to gas the situation of fluctuations in discharge situation judgement formation hydrate under existence conditions of reactor.That is, method of the present invention also can further comprise the step of judging hydrate formational situation under existence conditions according to the fluctuations in discharge situation of gas turnover reactor.
Wherein, when the gas flow that freeboard is drawn reactor from the reactor after beginning to test remains unchanged always, can judge not form hydrate under existence conditions; When the gas flow that freeboard is drawn reactor from the reactor after beginning to test reduced, can judge had hydrate to form under existence conditions.
Further, when having hydrate to form, method of the present invention can also comprise:
The gas flow of drawing reactor when freeboard from reactor reduces close to the minimum range of under meter, when under meter does not have flow indication, thereby the gaseous tension that improves freeboard under reactor improves the pressure reduction of upper and lower freeboard, continues the flow of measurement gas turnover reactor;
When improving pressure reduction, the gas flow that freeboard is drawn reactor from the reactor during in respect of flow indication, continues experiment greater than the minimum range of under meter, flow;
When pressure reduction is brought up to enough large (for example greater than 15% of upper and lower air chamber mean pressure, perhaps approach or equal upper and lower air chamber mean pressure 20% or higher), the gas flow that freeboard is drawn reactor from the reactor judges that the hydrate trap forms during still lower than the minimum range of under meter;
(be not 0 numerical value when occurring at the gas flow that under a certain pressure reduction, freeboard is drawn reactor from the reactor reducing and being reduced to certain value, flow is in respect of showing) after keep constant and no longer change, judge that hydrate still is not enough to trap under existence conditions.
According to another specific embodiments of the present invention, method of the present invention is that simulation forms the process of hydrate by migrated to the plenum system that discharges gas in porous medium by the saturated aqueous solution of gas, and described method comprises:
To be full of the reactor inner room by the saturated aqueous solution of experimental gas, begin experiment, will be contained in being entered reactor inner room, bottom-up seepage flow by the saturated aqueous solution of experimental gas from reactor lower part and return to water pot through the porous medium fill area and after draw on reactor top in a water pot; Keep gaseous tension and homo(io)thermism in water pot in experimentation, in water pot, gaseous tension is constant replenishes experimental gas in water pot in order to keep.In the method, can judge the situation that forms hydrate under existence conditions according to the situation of replenishing experimental gas in water pot.That is, method of the present invention also can further comprise the step of judging hydrate formational situation under existence conditions according to the situation of replenishing experimental gas in water pot.
Wherein, be zero for keeping the constant amount of replenishing experimental gas in the water pot of gaseous tension in water pot after beginning to test, judge not form hydrate under existence conditions; For keeping the constant amount of replenishing experimental gas in the water pot of gaseous tension in water pot greater than zero, judging has hydrate to form under existence conditions after beginning to test.
Further, when having hydrate to form, also the formational situation of hydrate can be judged according to the liquid flow rate situation further, wherein: when the total amount of replenishing experimental gas in water pot no longer changes, during simultaneously basic absence of liquid turnover reactor, judge that the hydrate trap forms; When the total amount of replenishing experimental gas in water pot no longer changes, when still having simultaneously liquid turnover reactor, judge that hydrate still is not enough to trap under existence conditions.
On the other hand, the present invention also provides a kind of device of simulating gas hydrate accumulation process under one-dimensional condition, and this device comprises:
The one dimension high-pressure reactor, this reactor inner room is divided into upper, middle, and lower part, and middle portion is for being used for generating the moisture porous medium fill area of hydrate, and the upper and lower part is divided into freeboard;
Airing system, this airing system is in order to experimental gas is introduced the reactor inner room from reactor lower part, make experimental gas seepage flow through the water water generation reaction compound in porous medium fill area and porous medium, and the experimental gas that will not react is drawn from reactor top.
According to specific embodiments of the present invention, described airing system can comprise the gas recycle system and/or fluid circulation.
The described gas recycle system mainly comprises surge tank, recycle compressor and gas tank, this gas recycle system is mainly for the plenum system of simulation free gas to porous medium layer diffusion or infiltration, more particularly, this gas recycle system is in order to described experimental gas is entered reactor after gas tank is drawn, and be introduced into surge tank after in the freeboard of reactor top, unreacted experimental gas is drawn reactor, then return to again gas tank through after recycle compressor.
Described fluid circulation mainly comprises volume pump and high pressure water pot, this fluid circulation is mainly to be migrated to by the saturated aqueous solution of experimental gas the plenum system that porous medium discharges gas for simulation, more particularly, this fluid circulation be utilize described volume pump with in the high pressure water pot introduced reactor by the saturated aqueous solution of experimental gas, the porous medium fill area and return to the high pressure water pot after draw on reactor top of flowing through; And the high pressure water pot is provided with the making-up air device in order to make-up gas in the high pressure water pot.
According to specific embodiments of the present invention, in the device of simulation gas hydrate accumulation process under one-dimensional condition of the present invention, also further comprise test macro and thermostatic control system;
Described test macro comprises:
1. putting the thermopair in high-pressure reactor, is mainly in order to assaying reaction device interior reaction temperature; And
2. put the pressure transmitter of the gas meter in order to the gas flow of measuring the turnover reactor in the gas recycle system, monitoring reaction device easy on and off space pressure and the differential pressure transmitter in reactor easy on and off space; And/or
Be arranged on the liquid meter in fluid circulation, in order to measure the liquid flow rate in fluid circulation; With the flow of air supply meter of high pressure water pot, keep gaseous tension in water pot constant and replenish the amount of experimental gas in the water pot in order to be determined as;
Described thermostatic control system comprises:
Control the water bath with thermostatic control of the gas recycle system and/or fluid circulation temperature and the constant temperature air bath of control one dimension reaction under high pressure actuator temperature; Perhaps,
The thermostatic chamber of accommodating described one dimension high-pressure reactor, the gas recycle system and/or fluid circulation.
Experimental installation of the present invention is mainly to be the gas hydrate of simulation under the one-dimensional condition forming process of gas hydrate particularly, best 〉=5 of reactor length-to-diameter ratio (being mainly the length-to-diameter ratio of reactor inner room porous medium filler section), for example the length-to-diameter ratio scope can be 5～100, be preferably greater than 10, that is, reactor of the present invention is one dimension long tube reactor.The reactor inside diameter scope is preferably 10～50mm.During concrete enforcement, reactor also can comprise two porous plugs, and described two porous plugs are divided into upper, middle, and lower part with the reactor inner room.In addition, reactor should tolerate certain experimental pressure and temperature, requires reactor can tolerate the pressure of 0～40MPa and the temperature of-30 ℃～40 ℃ (miscellaneous part in apparatus of the present invention such as high pressure water pot preferably also can tolerate this pressure and temperature) in the present invention.The main body of reactor of the present invention (long tube) can be to comprise sapphire pipe and/or stainless steel tube, selects sapphire pipe that the visuality of experiment can be provided.According to of the present invention one preferred specific embodiments, described reactor is that stainless steel tube and sapphire pipe up and down segmentation combine, can improve the visual of simulated experiment and suitably reduce costs, simultaneously, after hydrate forms, when needing microcosmic observation, sapphire pipe can also be unloaded, put under low temperature environment, carry out nuclear magnetic resonance scanning.
In method and apparatus of the present invention, described porous medium can comprise: one or more in the porous mediums such as quartz sand, silica gel, marine bottom sediment, gac, diatomite, asbestos, wilkinite, molecular sieve, carclazyte, activated alumina, pure aluminium silicate and pottery.
In the present invention, the contained water that is used for generating hydrate in described porous medium, and the aqueous solution in fluid circulation mesohigh water pot, can be the various hydrous matters that can generate hydrate, for example: pure water, or saliferous, contain alcohol, contain the aqueous solution of hydrate inhibitor or tensio-active agent, or natural sea-water etc.
Method and apparatus of the present invention goes for simulating the hydrate formation of pure gas, also goes for the hydrate formation of simulated dual component or more multi-component mixed gas, Sweet natural gas.The gas of method of the present invention able to generate hydrate applicatory comprises, but be not limited to one or more in following material: methane, ethane, propane, carbonic acid gas, nitrogen, hydrogen sulfide or its mixture, can be also the mixed gas of butane or pentane and above-mentioned micro-molecular gas (such as methane, ethane or nitrogen etc.), can be also the Sweet natural gases such as stratum free gas, associated gas.
In sum, utilize apparatus and method of the present invention, the fate that can simulating hydrate forms is moved with water transport and is moved two kinds of forms, simultaneously can also simulating hydrate from nucleation induce, hydrate forms gradually, hydrate becomes the Tibetan until the whole process of trap, apparatus and method of the present invention, can be used for investigating the impact that various experiment conditions become to hide on gas hydrate, significant for one-tenth Tibetan mechanism and the regularity of distribution of researching natural gas hydrate.
Description of drawings
Fig. 1 is for showing the simulated experiment schematic flow sheet of hydrate Forming process of the present invention.
Fig. 2 hides forming process simulator structural representation for showing according to the hydrate of a specific embodiment of the present invention.
Fig. 3 has shown that accumulation rate of consumption that methane gas hydrate in embodiment 1 becomes methane in the process of Tibetan over time.
Fig. 4 has shown that in embodiment 2, tonifying Qi total amount (under the normal conditions) over time.
Embodiment
Below in conjunction with embodiment and specific embodiment, the present invention is done detailed description further, be intended to help the reader to understand better technical spirit of the present invention and the beneficial effect that can produce, can not be interpreted as any restriction to the scope of the present invention.
See also illustrated in figures 1 and 2ly, a kind of experimental installation of simulating gas hydrate forming process under one-dimensional condition provided by the invention mainly comprises:
(1) reactor 1: this reactor 1 is the core of apparatus of the present invention, the withstand voltage scope 0～40MPa of this reactor 1, temperature resistant range-30 ℃～40 ℃.Reactor 1 inside diameter ranges can be 10～50mm, and the length-to-diameter ratio scope can be 5～100, is preferably greater than 10; Wherein, two porous plugs 2 are divided into three parts with the inner room of reactor 1, and middle portion is the porous medium fill area, and the upper and lower part is divided into two freeboards (during application, middle portion should be as far as possible longer, to guarantee long reaction compartment).The Main Function of porous plug 2 is to support the porous medium that is filled in the middle portion between two porous plugs, and the physical strength of porous plug can be decided according to experimental pressure and medium-weight.Evenly offer a plurality of holes on porous plug, to facilitate the circulation of gas and liquid, in the present invention, size and requirement of experiment according to porous medium, the percentage of open area of porous plug may be selected to be 30%～80%, and bore dia and pitch of holes press percentage of open area and the porous plug size is calculated, further, for prevent that porous medium from spilling from the porous consent, the porous screen cloth all can be laid in the below of upper porous plug and the top of lower porous plug.Upper and lower two freeboards can fill High-Voltage Experimentation gas according to the difference of object of experiment, also can fill High-Voltage Experimentation liquid such as seawater etc.Shown in Figure 2, reactor of the present invention is preferably stainless steel tube 1A and sapphire pipe 1B up and down segmentation combines, can improve the visuality of simulated experiment, simultaneously, after hydrate forms, when needing microcosmic observation, sapphire pipe 1B can be unloaded, put under low temperature environment, carry out nuclear magnetic resonance scanning.
(2) the gas recycle system: this gas recycle system mainly comprises surge tank 3, recycle compressor 4 and gas tank 5; This gas recycle system is in order to described experimental gas is entered reactor 1, bottom-up seepage flow through the porous medium fill area after gas tank 5 is drawn, and be introduced into surge tank 3 after in reactor 1 top freeboard, unreacted experimental gas is drawn reactor 1, then return to again gas tank 5 through after recycle compressor 4, thereby form the gas circulation;
(3) fluid circulation (water circulation system): this fluid circulation mainly comprises volume pump 6 and high pressure water pot 7; This fluid circulation be utilize described volume pump 6 with in high pressure water pot 7 introduced reactor 1 by the saturated aqueous solution of experimental gas, the porous medium fill area and return to high pressure water pot 7 after draw on reactor top of flowing through, thereby form the liquid circulation; And high pressure water pot 7 also is provided with in order to the making-up air device to high pressure water pot 7 interior make-up gas.
(4) test macro: this test macro mainly comprises the thermopair (not shown) that is arranged in high-pressure reactor 1; Put the differential pressure transmitter that assaying reaction device 1 is imported and exported the pressure transmitter of the gas meter of gas flow, assaying reaction device 1 easy on and off space gaseous tension and reactor 1 easy on and off space that is used in the gas recycle system; Be arranged in fluid circulation in order to the liquid meter of the liquid flow rate of measuring turnover reactor 1 and the flow of air supply meter of high pressure water pot 7.
(5) thermostatic control system: described thermostatic control system is preferably thermostatic chamber 8 (shown in Figure 2), is about to whole experimental installation (comprise reactor 1, and the gas recycle system and/or fluid circulation) and is positioned in thermostatic chamber 8; Described thermostatic control system also can be divided into several control temperature units, for example, one dimension high-pressure reactor 1 and relevant pipeline and testing instrument are positioned in constant temperature air bath, fluid circulation adopts water bath with thermostatic control, the pipeline of the front gas recycle system of reactor 1 adopts coil form, with constant temperature water bath.
Under simulation one-dimensional condition of the present invention, the experimental installation of gas hydrate forming process also comprises necessary pipeline (pipeline) and opening-closing valve etc.
Experimental installation of the present invention, the true formational situation that can be used for the simulated sea bottom gas hydrate, wherein considered two kinds of plenum systems: a kind of fate that is simulating hydrate forms is moved form, namely simulates free gas to the plenum system of porous medium layer diffusion or infiltration; Another kind is that the water transport that simulating hydrate forms moves form, namely simulates by the saturated aqueous solution of the gases such as methane and migrates to the plenum system that discharges gas in porous medium.
The fate that simulating hydrate forms is moved form device used and is mainly comprised above-mentioned reactor 1, the gas recycle system (comprising surge tank 3, recycle compressor 4 and gas tank 5) and relevant test macro and thermostatic control system, and the fate that simulating hydrate forms is moved the corresponding analogue experiment method of form and can be comprised the following steps:
At first thermostatic control system is set to certain assigned temperature (experimental temperature), then moisture porous medium is loaded in reactor 1, water saturation is generally 5%～100%, is specifically decided by the actual formation conditioned disjunction experiment condition of simulation.And moisture porous medium is carried out suitable compaction treatment, compaction can determine according to actual formation condition and medium porosity requirement etc.
Again the high pressure gas in gas tank 5 are slowly introduced reaction system from the bottom of reactor 1, on maintenance reactor 1, the pressure reduction of lower chamber can not be too large, prevent the movement of porous medium layer, the magnitude of pressure differential of upper lower chamber is generally lower than 20% of upper and lower air chamber mean pressure, approximately a few KPa to one thousand KPa specifically can be decided by gas phase media type and requirement of experiment.The actual environment in the pressure simulation seabed of upper and lower air chamber and deciding.
When the pressure of upper and lower air chamber reaches set(ting)value, begin experiment, start recycle compressor 4, the gas recycle system is started working, and makes gas slow seepage flow in porous medium.Gas flow rate is decided by porous medium hole condition, experimental pressure and the actual formation situation simulated.
In experimentation by pressure maintaining valve keep the upper and lower freeboard of reactor 1 (air chamber) pressure and pressure reduction constant, measure upper and lower air chamber gas flow over time.The instantaneous delivery of upper and lower gas meter indication is poor can be used as the speed that current gas reforming is hydrate, and the integrated flow of upper and lower gas meter is poor is the total amount of hydrate for gas reforming.The data such as flow, pressure reduction, pressure all can be by the computer online acquisition, and instantaneous delivery is poor and integrated flow is poor can be converted to by data on flows.
When upper lower chamber gas flow remains unchanged always after beginning experiment, show not form hydrate under existence conditions.
Reducing appears in the upper chamber gas flow after beginning to test, and expression has hydrate to form.When having hydrate to form, during when the reduction of upper chamber gas flow and close to the minimum range of under meter (under meter does not have flow indication), suitably improve the pressure of lower chamber, namely put on lower high air-chamber differential pressure.
When improving pressure reduction, the flow of upper chamber continues above-mentioned experiment during in respect of flow indication.When pressure reduction is increased to enough greatly, for example greater than 15% of upper and lower air chamber mean pressure, perhaps near 20% of upper and lower air chamber mean pressure, the gas flow of upper chamber shows that still lower than minimum range hydrate " trap " forms.The range ability of gas meter can be determined by experiment condition.
When under a certain pressure reduction, after beginning experiment, reducing appears in the upper chamber gas flow, and keeps constant after being reduced to certain value, and flow no longer changes, and shows that the growing amount total amount of hydrate is less, and hydrate still is not enough to trap under existence conditions.
Can find out, in above-mentioned simulated experiment process,, the integrated flow poor variation that can obtain due to hydrate form the gas consumption that cause poor by the instantaneous delivery of upper and lower gas meter indication determines that thus hydrate forms speed and formation volume.Simultaneously also can be by the pressure reduction Calculation of Gas variation of resistance to flow in flow event in porous medium that improves constantly, the formation volume of judgement hydrate, the forming process of simulating hydrate trap.
The water transport that simulating hydrate forms moves form device used and mainly comprises above-mentioned reactor 1, fluid circulation (volume pump 6, high pressure water pot 7) and relevant test macro and thermostatic control system, and the water transport that simulating hydrate forms moves the corresponding analogue experiment method of form can move with reference to the fate that aforementioned simulating hydrate forms the experimental procedure design of form.in this simulated experiment process, be pressed into the bottom freeboard of reactor 1 by volume pump 6 by the saturated aqueous solution of high pressure gas in high pressure water pot 7, (solution flow rate is by porous medium hole condition to infiltrate porous medium layer by lower porous plug 2, experimental pressure and the actual formation situation simulated and decide), keep gaseous tension and homo(io)thermism in water pot 7 in experimentation, for keeping in water pot 7 the constant make-up gas in the water pot 7 as required of gaseous tension, and be provided with gas meter above the high pressure water pot, can measure the flow of the gas make-up that causes due to the interior gas consumption of water pot 7.
So that hydrate when forming, does not have gas consumption in reactor 1, it is constant that the gaseous tension in high pressure water pot 7 keeps when the experiment condition deficiency, and the flow of gas meter in high pressure water pot 7 (flow of air supply meter) does not change.
When experiment condition is enough to make hydrate to form, due to by the saturated water of high pressure gas by reactor 1 time, gas in water forms hydrate and is consumed in reactor 1, the water that flows back in water pot 7 is no longer saturated, therefore the part high pressure gas dissolve in aqueous phase to keep state of saturation in water pot 7, cause the pressure decreased in water pot 7, need to by extraneous gas replenish to keep constant experimental pressure, the speed of tonifying Qi is the gas reforming speed of hydrate formation in the water pot 7.
When having hydrate to generate, in reactor 1, along with the continuous formation of hydrate, the hole in porous medium reduces, and under constant pressure, the flow of volume pump 6 will diminish.The pressure no longer tonifying Qi that remains unchanged in water pot 7, the flow of volume pump 6 is reduced to when substantially not showing simultaneously, shows that hydrate " trap " forms; The pressure no longer tonifying Qi that remains unchanged in water pot 7, but volume pump 6 shows that hydrate still is not enough to trap under existence conditions when still having flow indication.
Being applicable to described porous medium of the present invention has: quartz sand, silica gel, marine bottom sediment, gac can be also the porous mediums such as diatomite, asbestos, wilkinite, molecular sieve, carclazyte, activated alumina, pure aluminium silicate or pottery.The aqueous specimen that be used for to generate hydrate can be the various hydrous matters that can generate hydrate, and for example: pure water, contains alcohol, contains the aqueous solution of hydrate inhibitor or tensio-active agent saliferous.Method of the present invention, the hydrate that goes for pure gas becomes to hide process simulation, and the hydrate that also goes for two-pack or more multi-component mixed gas, Sweet natural gas becomes to hide process simulation.The gas of method of the present invention able to generate hydrate applicatory can comprise, but be not limited to one or more in following material: methane, ethane, propane, carbonic acid gas, nitrogen, hydrogen sulfide or its mixture, can be also the mixed gas of butane or pentane and above-mentioned micro-molecular gas (such as methane, ethane or nitrogen etc.), can be also the Sweet natural gases such as stratum free gas, associated gas.Utilize apparatus and method of the present invention, can investigate the impact that various experiment conditions become to hide on gas hydrate.
Embodiment 1: methane becomes to hide simulation to the One-Dimensional Water compound of porous medium layer diffusion
in the present embodiment, hide forming process simulated experiment flow process according to hydrate, designed the one dimension high-pressure reactor that contains four sections high pressure blind pipe 1A and three sections high pressure sapphire pipe 1B combinations, as shown in Figure 2, analogue experiment installation in the present embodiment comprises that mainly (internal diameter is 25.4mm to one dimension high-pressure reactor 1, overall length 1.2m, the length-to-diameter ratio of porous medium filled band approximately 42), surge tank 3, recycle compressor 4, gas tank 5, and test macro, thermostatic control system, the main body of thermostatic control system is cryogenic thermostat chamber 8, the main part one dimension reactor 1 of device, each connection line, under meter, differential pressure transmitter, pressure transmitters etc. all are positioned in cryogenic thermostat chamber 8, to keep the homo(io)thermism of whole system.In experimentation, at first system temperature is set and is maintained at 4 ℃ of experimental temperatures.Then moisture porous medium is filled in one dimension reactor 1, porous medium is selected 80～100 order quartz sands, and water saturation is 70%, and carries out compaction treatment according to experimental pressure.After vacuumizing in reactor, open reactor 1 bottom valve, slowly advance methane gas, until the pressure of reactor 1 upper and lower air chamber reaches respectively experimental pressure 5.8MPa and 6.0MPa, keep the pressure reduction of lower chamber on reactor 1 in intake process in 0.2MPa.Start recycle compressor 4, make slow seepage flow in the quartz sand of methane gas in reactor 1, keep the upper and lower air chamber pressure of reactor 1 to be respectively 5.8MPa and 6.0MPa by pressure maintaining valve, back pressure valve in experimentation, pressure reduction is constant is 0.2MPa, a under meter is respectively installed in reactor 1 top and below, measures the gas flow in Reactor inlet, exit over time.
The instantaneous delivery of upper and lower gas meter indication is poor can be used as the speed that current gas reforming is hydrate, has listed the accumulation rate of consumption of methane in the methane gas hydrate formation in Fig. 3 over time.initial stage, on, the numerical value of lower gas meter equates, hydrate not yet forms, be in induction period, approximately 23 minutes time, there is subsequently hydrate to generate, therefore methane gas consumes, the pressure of upper chamber is under the effect of back pressure valve, keep the constant pressure of upper chamber in reactor, therefore the expellant gas flow reduces, continuous generation along with hydrate, formation speed has the trend of increase, the gas that passes through porous medium is consumed mostly, the flow of upper chamber under meter reduces gradually, and close to zero, at this moment, improve the pressure of lower chamber to 6.2MPa, the pressure reduction that makes lower chamber is 0.4MPa, to increase the flow of gas.Can find equally, the flow of upper chamber reduces gradually, is on the one hand that the consumption due to gas causes, is that the hole in porous medium is occupied by hydrate gradually and causes because the hydrate big area forms on the other hand.Close to zero the time, continue to increase the pressure of lower chamber when gas flow, make gas can pass through the porous medium layer that hole reduces gradually.After pressure reduction is increased to 0.8MPa, only there is a small amount of hydrate to continue to form, and there is no gradually flow indication, still there is no gas flow when continuing to improve pressure reduction to 1.0MPa, show that hydrate " trap " forms.
Embodiment 2: migrated to by the saturated aqueous solution of the gases such as methane the One-Dimensional Water compound that discharges gas in porous medium and become to hide simulation
Adopt the device shown in Fig. 2, mainly comprise one dimension high-pressure reactor 1 (reactor 1 scantlings of the structure is with embodiment 1), volume pump 6, high pressure water pot 7, and test macro, thermostatic control system.The temperature of keeping in high-pressure reactor 1 and high pressure water pot 7 etc. is in 2 ℃ of set(ting)values, and high pressure gas are passed into high pressure water pot 7, and the whipping appts in opening high pressure water pot 7 makes high pressure gas water-soluble, and reaches capacity.Porous medium is filled in one dimension reactor 1, and porous medium is selected 80～100 order quartz sands, and carries out compaction treatment.After vacuumizing, open reactor 1 bottom valve, start volume pump 6, entered the bottom freeboard of reactor 1 by the saturated hydraulic pressure of high pressure gas in high pressure water pot 7, infiltrate porous medium layer by porous plug 2, and be full of the top freeboard of reactor 1, and by volume pump 6, liquid is circulated between high pressure water pot 7, reactor 1.Begin experiment, keeping in water pot gas temperature constant in experimentation is 2.0 ℃, stirring in high pressure water pot 7 is in opened condition always and is in saturated to guarantee the liquid that enters reactor 1, the constant of pressure completed by make-up gas, and remaining 6.0MPa, additional gas volume is recorded by gas meter.
tonifying Qi total amount curve is over time listed in Fig. 4, as seen from Figure 4, in initial for some time, because hydrate does not form, water in water pot 7 keeps state of saturation, air compensation is a horizontal linear, after 16 minutes, hydrate begins to form, consumed thus the methane gas that dissolves in the liquid phase, the water that flows back to high pressure water pot 7 is in undersaturated condition, the pressure of high pressure water pot 7 decreases, this pressure difference is made up by live gas, simultaneously the concentration difference of the stirring in high pressure water pot 7 and liquid phase makes the methane gas middle maintenance liquid phase that is soluble in the aqueous phase be in state of saturation.In the solubleness of aqueous phase and little, the forming process of hydrate is longer due to methane gas, and approximately the gas in 8 hours water pots no longer consumes, and volume pump 6 do not have flow indication, shows that hydrate " trap " forms.
Claims (6)
1. method of simulating gas hydrate accumulation process under one-dimensional condition, the method is utilized a kind of device, and this device comprises:
One dimension high-pressure reactor, this reactor comprise two porous plugs, and described two porous plugs are divided into upper, middle, and lower part with the reactor inner room, and middle portion is for being used for generating the moisture porous medium fill area of hydrate, and the upper and lower part is divided into freeboard; Described reactor can tolerate the pressure of 0～40MPa and the temperature of-30 ℃～40 ℃, and the reactor inside diameter scope is 10～50mm, and the length-to-diameter ratio of reactor inner room porous medium fill area is 5～100;
Airing system, this airing system is in order to experimental gas is introduced the reactor inner room from reactor lower part, make experimental gas seepage flow through the water water generation reaction compound in porous medium fill area and porous medium, and the experimental gas that will not react is drawn from reactor top;
This device also comprises test macro and thermostatic control system;
Described test macro comprises:
1. put the thermopair in high-pressure reactor; And
2. put the pressure transmitter of the gas meter in order to the gas flow of measuring the turnover reactor in the gas recycle system, monitoring reaction device easy on and off space pressure and the differential pressure transmitter in reactor easy on and off space; And/or
Be arranged on liquid meter in fluid circulation and the flow of air supply meter of high pressure water pot;
Described thermostatic control system comprises:
Control the water bath with thermostatic control of the gas recycle system and/or fluid circulation temperature and the constant temperature air bath of control one dimension reaction under high pressure actuator temperature; Perhaps,
The thermostatic chamber of accommodating described one dimension high-pressure reactor, the gas recycle system and/or fluid circulation;
The method is to utilize at one dimension high-pressure reactor inner room formation hydrate to come the analog gas hydrate to become the Tibetan process; The method comprises:
Experimental gas is introduced the reactor inner room from reactor lower part, make experimental gas from bottom to top seepage flow through the porous medium fill area, generate hydrate in the porous medium fill area, and unreacted experimental gas is drawn from reactor top;
Determine that by mensurated gas composition fluctuations in discharge in flow event in porous medium hydrate forms speed;
And the method is that simulation forms the process of hydrate to the plenum system of porous medium layer diffusion or infiltration by free gas; Perhaps, the method is that simulation forms the process of hydrate by migrated to the plenum system that discharges gas in porous medium by the saturated aqueous solution of gas; Wherein:
Simulation comprises by the process of free gas to the plenum system formation hydrate of porous medium layer diffusion or infiltration: the experimental gas of dissociating is filled with reactor, make reactor easy on and off space gaseous tension reach experimental pressure, begin experiment, make free experimental gas enter reactor inner room, bottom-up seepage flow through porous medium, drawn from reactor top again from reactor lower part; Keep the upper and lower freeboard gaseous tension of reactor and pressure reduction constant in the single experiment process, in the experiments of measuring process, the flow of gas turnover reactor over time, judges according to the fluctuations in discharge situation of gas turnover reactor the situation that forms hydrate under existence conditions;
Simulation forms hydrate by migrated to the plenum system that discharges gas in porous medium by the saturated aqueous solution of gas process comprises: will be full of the reactor inner room by the saturated aqueous solution of experimental gas, begin experiment, will be contained in being entered reactor inner room, bottom-up seepage flow by the saturated aqueous solution of experimental gas from reactor lower part and return to water pot through the porous medium fill area and after draw on reactor top in a water pot; Keep gaseous tension and homo(io)thermism in water pot in experimentation, in water pot, gaseous tension is constant replenishes experimental gas in water pot in order to keep, and judges according to the situation of replenishing experimental gas in water pot the situation that forms hydrate under existence conditions.
2. method according to claim 1, the method are that simulation forms the process of hydrate to the plenum system of porous medium layer diffusion or infiltration by free gas, and the method also comprises:
When the gas flow that freeboard is drawn reactor from the reactor after beginning to test is reduced to less than the minimum range of under meter, thereby the gaseous tension that improves freeboard under reactor improves the pressure reduction of upper and lower freeboard, continues the flow of measurement gas turnover reactor.
3. method according to claim 1, wherein,
Described porous medium comprises: one or more in quartz sand, silica gel, marine bottom sediment, gac, diatomite, asbestos, wilkinite, molecular sieve, carclazyte, activated alumina, pure aluminium silicate and pottery;
In described porous medium, the contained water that is used for generating hydrate is: pure water, or saliferous, contain alcohol, contain the aqueous solution of hydrate inhibitor or tensio-active agent, or natural sea-water;
Described experimental gas comprises: methane, ethane, propane, carbonic acid gas, nitrogen, hydrogen sulfide or its mixture, the mixed gas of butane or pentane and micro-molecular gas methane, ethane or nitrogen, stratum free gas, or associated gas.
4. device that is used for realizing the method for the described simulation gas hydrate accumulation process under one-dimensional condition of claim 1～3 any one, this device comprises:
One dimension high-pressure reactor, this reactor comprise two porous plugs, and described two porous plugs are divided into upper, middle, and lower part with the reactor inner room, and middle portion is for being used for generating the moisture porous medium fill area of hydrate, and the upper and lower part is divided into freeboard; Described reactor can tolerate the pressure of 0～40MPa and the temperature of-30 ℃～40 ℃, and the reactor inside diameter scope is 10～50mm, and the length-to-diameter ratio of reactor inner room porous medium fill area is 5～100;
Airing system, this airing system is in order to experimental gas is introduced the reactor inner room from reactor lower part, make experimental gas seepage flow through the water water generation reaction compound in porous medium fill area and porous medium, and the experimental gas that will not react is drawn from reactor top;
This device also comprises test macro and thermostatic control system;
Described test macro comprises:
1. put the thermopair in high-pressure reactor; And
2. put the pressure transmitter of the gas meter in order to the gas flow of measuring the turnover reactor in the gas recycle system, monitoring reaction device easy on and off space pressure and the differential pressure transmitter in reactor easy on and off space; And/or
Be arranged on liquid meter in fluid circulation and the flow of air supply meter of high pressure water pot;
Described thermostatic control system comprises:
Control the water bath with thermostatic control of the gas recycle system and/or fluid circulation temperature and the constant temperature air bath of control one dimension reaction under high pressure actuator temperature; Perhaps,
The thermostatic chamber of accommodating described one dimension high-pressure reactor, the gas recycle system and/or fluid circulation.
5. device according to claim 4, wherein, described airing system comprises the gas recycle system and/or fluid circulation;
The described gas recycle system comprises surge tank, recycle compressor and gas tank, this gas recycle system is in order to described experimental gas is entered reactor after gas tank is drawn, and be introduced into surge tank after in the freeboard of reactor top, unreacted experimental gas is drawn reactor, then return to again gas tank through after recycle compressor;
Described fluid circulation comprises volume pump and high pressure water pot, this fluid circulation be utilize described volume pump with in the high pressure water pot introduced reactor by the saturated aqueous solution of experimental gas, the porous medium fill area and return to the high pressure water pot after draw on reactor top of flowing through; And the high pressure water pot is provided with the making-up air device in order to make-up gas in the high pressure water pot.
6. device according to claim 4, wherein, the main body of described reactor comprises sapphire pipe and/or stainless steel tube.
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