CN113294126A - Natural gas hydrate combined mining method and device for stabilizing stratum - Google Patents
Natural gas hydrate combined mining method and device for stabilizing stratum Download PDFInfo
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- 238000005065 mining Methods 0.000 title claims abstract description 63
- 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 51
- 238000000034 method Methods 0.000 title claims abstract description 39
- 230000000087 stabilizing effect Effects 0.000 title claims abstract description 27
- 239000007789 gas Substances 0.000 claims abstract description 144
- 238000002347 injection Methods 0.000 claims abstract description 144
- 239000007924 injection Substances 0.000 claims abstract description 144
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 121
- 238000004519 manufacturing process Methods 0.000 claims abstract description 102
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 61
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 60
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 43
- 239000008398 formation water Substances 0.000 claims abstract description 22
- 239000003345 natural gas Substances 0.000 claims abstract description 21
- 239000000463 material Substances 0.000 claims abstract description 20
- 239000013535 sea water Substances 0.000 claims abstract description 17
- 238000006243 chemical reaction Methods 0.000 claims abstract description 16
- 238000002791 soaking Methods 0.000 claims abstract description 10
- 238000003860 storage Methods 0.000 claims description 33
- 239000007788 liquid Substances 0.000 claims description 31
- 238000000926 separation method Methods 0.000 claims description 18
- VTVVPPOHYJJIJR-UHFFFAOYSA-N carbon dioxide;hydrate Chemical compound O.O=C=O VTVVPPOHYJJIJR-UHFFFAOYSA-N 0.000 claims description 9
- 238000000605 extraction Methods 0.000 claims description 7
- 230000015572 biosynthetic process Effects 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 5
- 230000009467 reduction Effects 0.000 claims description 5
- 239000000839 emulsion Substances 0.000 claims description 3
- 150000004677 hydrates Chemical class 0.000 claims 1
- 239000004568 cement Substances 0.000 description 9
- 238000006073 displacement reaction Methods 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 238000005553 drilling Methods 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 239000013589 supplement Substances 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- -1 natural gas hydrates Chemical class 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000002689 soil Substances 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 230000021715 photosynthesis, light harvesting Effects 0.000 description 2
- 230000001988 toxicity Effects 0.000 description 2
- 231100000419 toxicity Toxicity 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000009933 burial Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000008239 natural water Substances 0.000 description 1
- 238000009828 non-uniform distribution Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
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- 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
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
- Y02P90/70—Combining sequestration of CO2 and exploitation of hydrocarbons by injecting CO2 or carbonated water in oil wells
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Abstract
The invention discloses a natural gas hydrate combined mining method and a natural gas hydrate combined mining device for stabilizing a stratum, wherein the combined mining method comprises the following steps: building an offshore mining platform and an injection platform, and laying a mining well and a gas injection well, wherein the horizontal section of the mining well is laid at the junction position of an upper covering layer and a hydrate reservoir layer, and the horizontal section of the gas injection well is laid in the hydrate reservoir layer and is positioned below the horizontal section of the mining well; putting a perforation and fracturing combined tool under the gas injection well, injecting carbon dioxide hot medium to perform perforation and fracturing operation on the horizontal section of the gas injection well, and performing replacement reaction on the gas injection well after soaking; a production pipe column and a directional hydraulic perforation fracturing tool are put into the exploitation well, a support material, hot seawater and exploited formation water are injected into the production pipe column, perforation fracturing operation is carried out on a hydrate reservoir layer under the exploitation well, and a high diversion channel is formed and is used for communicating the hydrate reservoir layer between the horizontal section of the exploitation well and the horizontal section of the gas injection well; extracting natural gas and residual carbon dioxide gas.
Description
Technical Field
The invention relates to the technical field of natural gas hydrate exploitation, in particular to a natural gas hydrate combined exploitation method and device for stabilizing a stratum.
Background
The natural gas hydrate is a cage-shaped unit cell compound formed by natural gas and water under the environment of low temperature and high pressure, and the conservation estimation of the global hydrate resource amount is about 3.0 х 1015m3And the quantity of the oil gas resources is higher by one order of magnitude than that of the conventional oil gas resources. In addition, the natural gas hydrate has the characteristics of green and pollution-free combustion, is known as clean energy with the most development value and prospect in the 21 st century, and is expected to improve the energy framework of the current non-clean energy occupying the market leading.
The natural gas hydrate is mainly distributed in land permafrost zones with harsh engineering conditions and submarine sediments with water depth more than 300m, and more than 90% of the natural gas hydrate is distributed in ocean areas. The sea natural gas hydrate reservoir has the characteristics of shallow burial, poor cementation, poor permeability, non-uniform distribution and the like, and an overlying underlayer stratum generally has certain permeability. In order to realize large-area commercial exploitation of natural gas hydrates in the future, natural disasters and environmental problems such as geological collapse, collapse and natural gas leakage caused by large-area decomposition of the natural gas hydrates need to be concerned.
Aiming at the problem of stratum deformation and settlement caused by exploitation, the prior art adopts a method of injecting cement slurry into an overlying underlayer to form an artificial dense cover layer, so that the recovery ratio of a depressurization method is improved, andeffectively prevent methane leakage and prevent geological disasters. Or by injecting a displacement gas into the overlying underlayer to cause a displacement reaction to form CO2/N2The hydrate effectively enhances the soil body strength of the contact surface, reduces the creep deformation of the soil body of the contact surface and the relative displacement of different soil bodies, effectively increases the gas production rate of the reservoir and solves the problem of reservoir instability caused by direct mass mining. However, the above method has problems in three aspects: firstly, extra operation and measures are needed to realize the stabilization of the stratum and improve the exploitation cost, for example, a large amount of cement paste is injected by perforating operation on an overlying underlayer, the cost of the exploited material is improved, the environmental pollution is easy to cause, replacement gas is injected on the overlying underlayer, and the cost of the exploited material and time is improved due to the slow replacement reaction rate; secondly, the stable coverage, supporting strength and stabilizing effect of the stratum cannot be accurately known, the trend and action position of the injected material cannot be accurately known by adopting the operation of injecting cement slurry or injecting replacement gas to establish a stabilizing layer, and the overall balanced stabilizing effect of the mining area cannot be realized. Thirdly, the actual implementation of the project is difficult, and the cement slurry has an instant solidification phenomenon, so that a large amount of cement slurry is accumulated at the position close to the well casing of the perforation, and the transverse extension cannot be realized. Gas injection replacement has the problems of slow reaction rate and low replacement rate, a stable cover layer structure cannot be efficiently realized, and in addition, if stratum temperature and pressure do not meet the requirements of replacement conditions, the problems of replacement gas leakage and the like are easy to occur.
Disclosure of Invention
The invention provides a natural gas hydrate combined mining method and a natural gas hydrate combined mining device for stabilizing a stratum, aiming at the defects in the prior art.
The technical scheme adopted by the invention for solving the technical problems is as follows: a method of integrated natural gas hydrate production to create a consolidated formation, the integrated production method comprising:
well cementation: the method comprises the following steps of constructing an offshore mining platform and an injection platform, and respectively arranging a mining well connected with the mining platform and a gas injection well connected with the injection platform, wherein the horizontal section of the mining well is arranged at the junction position of an upper cover layer and a hydrate reservoir layer, and the horizontal section of the gas injection well is arranged in the hydrate reservoir layer and is positioned below the horizontal section of the mining well;
fracturing a gas injection well: putting a perforation and fracturing combined tool under the gas injection well, injecting carbon dioxide hot medium to perform perforation and fracturing operation on the horizontal section of the gas injection well, and performing replacement reaction on the gas injection well after soaking;
fracturing a production well: a production pipe column and a directional hydraulic perforation fracturing tool are put into the exploitation well, a support material, hot seawater and exploited formation water are injected into the production pipe column, perforation fracturing operation is carried out on a hydrate reservoir layer under the exploitation well, and a high diversion channel is formed and is used for communicating the hydrate reservoir layer between the horizontal section of the exploitation well and the horizontal section of the gas injection well;
an extraction step: and (4) putting a production casing under the exploitation well, and extracting natural gas and residual carbon dioxide gas.
In the method for producing gas hydrate in combination with stabilized formation according to the present invention, after the extracting step, the method for producing gas hydrate in combination further includes:
and opening the gas injection well, and repeating the gas injection well fracturing step, the production well fracturing step and the extraction step until the production is finished.
In the gas hydrate combined mining method for stabilizing the stratum, the horizontal section of the gas injection well is positioned at two thirds of the thickness of the hydrate reservoir from top to bottom.
In the method for jointly producing gas hydrate for stabilizing a stratum, before the step of fracturing the gas injection well, the method for jointly producing gas hydrate for stabilizing a stratum further comprises the following steps:
and (3) a step of pressure reduction mining: and (3) putting a production casing pipe under the gas injection well, carrying out depressurization exploitation, and stopping depressurization exploitation when the pressure of the hydrate reservoir is reduced to below 15% of the phase equilibrium pressure of the methane hydrate corresponding to the temperature of the hydrate reservoir.
In the gas hydrate combined production method for stabilizing the stratum, the fracturing step of the gas injection well specifically comprises the following steps:
putting a perforation and fracturing combined tool under the gas injection well, injecting a carbon dioxide hot medium to perform perforation and fracturing operation on the horizontal section of the gas injection well, and detecting temperature and pressure data of the horizontal section of the gas injection well;
stopping injecting the carbon dioxide heat medium when the temperature and pressure data of the horizontal section of the gas injection well reaches the phase equilibrium condition generated by the carbon dioxide hydrate;
and (4) carrying out replacement reaction by gas injection well soaking.
In the natural gas hydrate combined mining method for stabilizing the stratum, the fracturing step of the mining well specifically comprises the following steps:
when the temperature pressure data of the horizontal section of the gas injection well reaches the critical phase balance condition of methane hydrate generation, a production pipe column and a directional hydraulic perforation fracturing tool are put into the exploitation well, supporting materials, hot seawater and exploited formation water are injected into the production pipe column, perforation fracturing operation is carried out on a hydrate reservoir layer under the exploitation well, and a high diversion channel is formed and used for communicating the hydrate reservoir layer between the horizontal section of the exploitation well and the horizontal section of the gas injection well.
In the method for jointly exploiting natural gas hydrates for stabilizing the stratum, the carbon dioxide heat medium comprises one or more of gaseous carbon dioxide, liquid carbon dioxide, emulsion carbon dioxide, supercritical carbon dioxide or carbon dioxide gas mixture.
The other technical scheme adopted by the invention for solving the technical problem is as follows: constructing a natural gas hydrate combined exploitation device for stabilizing a stratum, wherein the combined exploitation device comprises an exploitation platform and an injection platform which are arranged on the sea, an exploitation well connected with the exploitation platform, and a gas injection well connected with the injection platform, wherein the horizontal section of the exploitation well is arranged at the junction position of an upper covering layer and a hydrate reservoir layer, and the horizontal section of the gas injection well is arranged in the hydrate reservoir layer and is positioned below the horizontal section of the exploitation well;
the combined mining apparatus further comprises:
the perforation and fracturing combined tool is used for putting into the gas injection well and injecting carbon dioxide heat medium to carry out perforation and fracturing operation on the horizontal section of the gas injection well;
the production pipe column and the directional hydraulic perforation fracturing tool are used for descending into the production well, injecting a supporting material, hot seawater and produced formation water into the production pipe column, carrying out perforation fracturing operation on a hydrate reservoir layer under the production well, and forming a high diversion channel for communicating the hydrate reservoir layer between the horizontal section of the production well and the horizontal section of the gas injection well;
and the production casing is used for descending into the production well and extracting natural gas and residual carbon dioxide gas.
In the natural gas hydrate combined exploitation device for stabilizing the stratum, the combined exploitation device further comprises a first gas-liquid separation storage device arranged on the exploitation platform, a first gas storage tank arranged on the exploitation platform and communicated with the first gas-liquid separation storage device, a hydraulic perforation fracturing device arranged on the exploitation platform, and a liquid storage heating device arranged on the exploitation platform and communicated with the hydraulic perforation fracturing device.
In the natural gas hydrate combined exploitation device for stabilizing the stratum, the combined exploitation device further comprises a second gas-liquid separation storage device arranged on the injection platform, a second gas storage tank arranged on the injection platform and communicated with the second gas-liquid separation storage device, a perforation and fracturing combined device arranged on the injection platform, and a liquid storage tank arranged on the injection platform and communicated with the second gas-liquid separation storage device.
The implementation of the natural gas hydrate joint mining method and the device for stabilizing the stratum has the following beneficial effects: when the natural gas hydrate combined mining method for stabilizing the stratum is implemented, the well body structure of the mining well is directly used as the structure for stabilizing the stratum, additional operation and measures are not needed to stabilize the stratum, the integrally balanced stabilizing state of a mining area can be realized, and the stability and the safety of the subsequent mining construction of a lower hydrate reservoir layer are facilitated. Secondly, the method adopts a mode of injecting a carbon dioxide thermal medium to carry out perforation fracturing and replacement operation on the gas injection well, can effectively supplement the heat lost by the stratum after pressure reduction exploitation, improves the fracturing range and the fracturing effect, and improves the rate and the efficiency of the replacement reaction. Furthermore, the invention adopts a mode of reinjecting produced stratum water to carry out perforation fracturing operation on the production well, can effectively and uniformly permeate the stratum water into the reservoir, and can combine with residual carbon dioxide gas to generate new carbon dioxide hydrate while forming a high diversion channel, thereby improving the replacement efficiency, uniformly generating stable carbon dioxide hydrate in the reservoir in a large range, and ensuring the stability of the reservoir. In addition, the method of reinjecting produced formation water can effectively solve the problem of treatment and discharge of the produced formation water, and because the produced formation water has biological toxicity and pollutes the environment and cannot be directly discharged, the reinjecting method not only can uniformly stabilize the formation, but also can realize the purposes of protecting the environment, simplifying the operation requirement and reducing the production cost. Meanwhile, the invention adopts hot seawater and carbon dioxide heat medium as fracturing fluid medium, adopts heat medium as perforating and fracturing operation material of the exploitation well and the injection well, supplements heat to the stratum in time during fracturing, and adopts a mode of interval injection from the upper well to the lower well and repeated exploitation steps for many times, so that the whole exploitation process does not need additional heating operation, has lower energy dissipation, and is beneficial to the temperature and pressure control of the whole hydrate reservoir.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic flow diagram of a first embodiment of a consolidated natural gas hydrate cogeneration method of this invention;
FIG. 2 is a schematic diagram of a first embodiment of a formation-stabilized natural gas hydrate cogeneration apparatus of the invention;
fig. 3 is a partial structural view of a first embodiment of the formation-stabilized natural gas hydrate cogeneration apparatus of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
As shown in fig. 1, in a first embodiment of the present invention, a method for consolidated natural gas hydrate cogeneration, the method comprises:
a well cementation step S101: and constructing an offshore mining platform and an injection platform, and respectively arranging a mining well connected with the mining platform and a gas injection well connected with the injection platform, wherein the horizontal section of the mining well is arranged at the junction position of the upper cover layer and the hydrate reservoir, and the horizontal section of the gas injection well is arranged in the hydrate reservoir and is positioned below the horizontal section of the mining well.
Selecting a sea natural gas hydrate reservoir as a mining object, respectively building an offshore mining platform and an injection platform, firstly, performing drilling operation of a mining well, arranging a horizontal well section of the mining well at the junction position of an upper covering layer and the hydrate reservoir, putting a casing into the well, and injecting cement into an annular space between the well and the casing to complete well cementation operation.
And then, performing drilling operation of the gas injection well, wherein the horizontal section of the gas injection well is distributed in the hydrate storage layer and is positioned below the horizontal section of the exploitation well, a sleeve is put in, and cement is injected into the annular space between the well hole and the sleeve to complete well cementation operation.
It is understood that in other embodiments, the gas injection well may be provided first, followed by the production well, or both.
Gas injection well fracturing step S102: and (3) putting a perforation and fracturing combined tool under the gas injection well, injecting carbon dioxide hot medium to perform perforation and fracturing operation on the horizontal section of the gas injection well, and performing replacement reaction on the gas injection well after soaking.
And (2) putting a perforation and fracturing combined tool under the gas injection well, performing perforation and fracturing operation on the horizontal section of the gas injection well, injecting a carbon dioxide heat medium for replacement reaction, controlling the temperature and pressure condition of a hydrate reservoir by controlling the pressure of an injection pump and the temperature of the carbon dioxide heat medium, stopping injecting the carbon dioxide heat medium when the temperature and pressure condition of the horizontal section of the gas injection well reaches the phase equilibrium condition generated by the carbon dioxide hydrate, and performing soaking replacement reaction on the gas injection well.
A producing well fracturing step S103: and (2) putting a production pipe column and a directional hydraulic perforation fracturing tool into the exploitation well, injecting a support material, hot seawater and exploited formation water into the production pipe column, performing perforation fracturing operation on a hydrate reservoir layer under the exploitation well, and forming a high diversion channel for communicating the hydrate reservoir layer between the horizontal section of the exploitation well and the horizontal section of the gas injection well.
Monitoring the temperature and pressure condition of the horizontal section of the gas injection well in real time, when the temperature and pressure condition is about to reach the critical phase equilibrium condition for generating methane hydrate, putting a production pipe column and a directional hydraulic perforation fracturing tool into the exploitation well, injecting a supporting material, hot seawater and exploitation formation water, performing perforation fracturing operation on a hydrate reservoir layer under (below) the horizontal section of the exploitation well, and forming a high diversion channel for communicating the horizontal section of the exploitation well with the hydrate reservoir layer of the horizontal section of the gas injection well.
An extraction step S104: and (4) putting a production casing under the exploitation well, and extracting natural gas and residual carbon dioxide gas.
And (4) putting a production casing under the exploitation well, and extracting natural gas and residual carbon dioxide gas obtained after the replacement reaction. It will be appreciated that the natural gas component is primarily methane gas.
Further, the natural gas and residual carbon dioxide gas obtained after the displacement reaction are extracted and treated by gas-liquid separation and storage equipment. Firstly, performing gas-liquid separation operation, separating formation water for hydraulic perforation fracturing operation of a production well, then performing gas separation on the separated natural gas and residual carbon dioxide gas, enabling the obtained pure natural gas to enter a gas storage tank for storage and transportation, and enabling the obtained carbon dioxide gas to form a carbon dioxide thermal medium again for subsequent injection displacement reaction.
When the natural gas hydrate combined mining method for stabilizing the stratum is implemented, the well body structure of the mining well is directly used as the structure for stabilizing the stratum, additional operation and measures are not needed to stabilize the stratum, the integrally balanced stabilizing state of a mining area can be realized, and the stability and the safety of the subsequent mining construction of a lower hydrate reservoir layer are facilitated. Secondly, the method adopts a mode of injecting a carbon dioxide thermal medium to carry out perforation fracturing and replacement operation on the gas injection well, can effectively supplement the heat lost by the stratum after pressure reduction exploitation, improves the fracturing range and the fracturing effect, and improves the rate and the efficiency of the replacement reaction. Furthermore, the invention adopts a mode of reinjecting produced stratum water to carry out perforation fracturing operation on the production well, can effectively and uniformly permeate the stratum water into the reservoir, and can combine with residual carbon dioxide gas to generate new carbon dioxide hydrate while forming a high diversion channel, thereby improving the replacement efficiency, uniformly generating stable carbon dioxide hydrate in the reservoir in a large range, and ensuring the stability of the reservoir. In addition, the method of reinjecting produced formation water can effectively solve the problem of treatment and discharge of the produced formation water, and because the produced formation water has biological toxicity and pollutes the environment and cannot be directly discharged, the reinjecting method not only can uniformly stabilize the formation, but also can realize the purposes of protecting the environment, simplifying the operation requirement and reducing the production cost. Meanwhile, the invention adopts hot seawater and carbon dioxide heat medium as fracturing fluid medium, adopts heat medium as perforating and fracturing operation material of the exploitation well and the injection well, supplements heat to the stratum in time during fracturing, and adopts a mode of interval injection from the upper well to the lower well and repeated exploitation steps for many times, so that the whole exploitation process does not need additional heating operation, has lower energy dissipation, and is beneficial to the temperature and pressure control of the whole hydrate reservoir.
During the production process, after the natural gas and residual carbon dioxide gas extraction, the combined production method further comprises:
and opening the gas injection well, and repeating the gas injection well fracturing step, the production well fracturing step and the extraction step until the production is finished.
Preferably, the horizontal section of the gas injection well is located at two thirds of the thickness of the hydrate reservoir from top to bottom.
Further, prior to the gas injection well fracturing step, the combined production method further comprises:
and (3) a step of pressure reduction mining: and (3) putting a production casing pipe under the gas injection well, carrying out depressurization exploitation, and stopping depressurization exploitation when the pressure of the hydrate reservoir is reduced to below 15% of the phase equilibrium pressure of the methane hydrate corresponding to the temperature of the hydrate reservoir.
Preferably, the gas injection well fracturing step specifically comprises:
and (3) putting a perforation and fracturing combined tool under the gas injection well, injecting a carbon dioxide hot medium to perform perforation and fracturing operation on the horizontal section of the gas injection well, and detecting temperature and pressure data of the horizontal section of the gas injection well.
And stopping injecting the carbon dioxide heat medium when the temperature and pressure data of the horizontal section of the gas injection well reaches the phase equilibrium condition of the generation of the carbon dioxide hydrate.
And (4) carrying out replacement reaction by gas injection well soaking.
Further preferably, the fracturing step of the production well specifically comprises:
when the temperature pressure data of the horizontal section of the gas injection well reaches the critical phase balance condition of methane hydrate generation, a production pipe column and a directional hydraulic perforation fracturing tool are put into the exploitation well, supporting materials, hot seawater and exploited formation water are injected into the production pipe column, perforation fracturing operation is carried out on a hydrate reservoir layer under the exploitation well, and a high diversion channel is formed and used for communicating the hydrate reservoir layer between the horizontal section of the exploitation well and the horizontal section of the gas injection well.
In this embodiment, the carbon dioxide thermal medium comprises one or more of gaseous carbon dioxide, liquid carbon dioxide, emulsion carbon dioxide, supercritical carbon dioxide, or a mixture of carbon dioxide.
As shown in fig. 2 to 3, in the first embodiment of the gas hydrate combined production device for stabilizing a stratum according to the present invention, the combined production device 10 comprises a production platform 11 and an injection platform 12 which are arranged at sea, a production well 13 connected with the production platform 11, and a gas injection well 14 connected with the injection platform 12, wherein a horizontal section of the production well 13 is arranged at the junction position of an upper cover layer 23 and a hydrate reservoir layer 24, and a horizontal section of the gas injection well 14 is arranged in the hydrate reservoir layer 24 and is positioned below the horizontal section of the production well 13;
the combined mining apparatus 10 further includes:
the perforating and fracturing combined tool is used for putting the gas injection well 14 and injecting carbon dioxide heat medium to perform perforating and fracturing operation on the horizontal section of the gas injection well 14;
the production string and the directional hydraulic perforation fracturing tool are used for descending the production well 13, injecting a supporting material 25, hot seawater and produced formation water into the production string, carrying out perforation fracturing operation on a hydrate reservoir 24 under the production well 13, and forming a high diversion channel for communicating the hydrate reservoir 24 between the horizontal section of the production well 13 and the horizontal section of the gas injection well 14;
a production casing for lowering into the production well 13 for extracting natural gas and residual carbon dioxide gas.
The combined mining apparatus 10 performs the combined mining method described above during operation.
The specific implementation mode of the combined mining device 10 is that an offshore mining platform 11 and an injection platform 12 are built, and a mining well 13 connected with the mining platform 11 and a gas injection well 14 connected with the injection platform 12 are respectively arranged, wherein the horizontal section of the mining well 13 is arranged at the junction position of an upper covering layer 23 and a hydrate reservoir layer 24, and the horizontal section of the gas injection well 14 is arranged in the hydrate reservoir layer 24 and is positioned below the horizontal section of the mining well 13.
Selecting a sea natural gas hydrate reservoir stratum 24 as a mining object, respectively building an offshore mining platform 11 and an injection platform 12, firstly, performing drilling operation of a mining well 13, arranging a horizontal well section of the mining well 13 at the junction position of an upper covering layer 23 and the hydrate reservoir stratum 24, putting a casing pipe in the well, and injecting cement into an annular space between a well hole and the casing pipe to finish well cementation operation.
And then, carrying out the drilling operation of the gas injection well 14, arranging the horizontal section of the gas injection well 14 in the hydrate reservoir stratum 24 and below the horizontal section of the exploitation well 13, putting a casing pipe, and injecting cement into the annular space between the well hole and the casing pipe to finish the well cementation operation.
It is understood that in other embodiments, the gas injection well 14 may be provided first, and then the production well 13 may be provided, or both.
And (3) putting a perforation and fracturing combined tool under the gas injection well 14, injecting carbon dioxide heat medium to carry out perforation and fracturing operation on the horizontal section of the gas injection well 14, and carrying out replacement reaction on the soaking well of the gas injection well 14.
And (2) putting a perforation and fracturing combined tool under the gas injection well 14, performing perforation and fracturing operation on the horizontal section of the gas injection well 14, injecting a carbon dioxide heat medium for a displacement reaction, controlling the temperature and pressure condition of the hydrate reservoir 24 by controlling the pressure of an injection pump and the temperature of the carbon dioxide heat medium, and stopping injecting the carbon dioxide heat medium when the temperature and pressure condition of the horizontal section of the gas injection well 14 reaches the phase equilibrium condition generated by the carbon dioxide hydrate, and performing soaking and displacement reaction on the gas injection well 14.
And (3) putting a production pipe column and a directional hydraulic perforation fracturing tool into the production well 13, injecting a supporting material 25, hot seawater and produced formation water into the production pipe column, and carrying out perforation fracturing operation on a hydrate reservoir 24 under the production well 13 to form a high diversion channel for communicating the hydrate reservoir 24 between the horizontal section of the production well 13 and the horizontal section of the gas injection well 14.
And monitoring the temperature and pressure condition of the horizontal section of the gas injection well 14 in real time, when the temperature and pressure condition is about to reach the critical phase equilibrium condition for generating methane hydrate, putting a production pipe column and a directional hydraulic perforation fracturing tool into the exploitation well 13, injecting a supporting material 25, hot seawater and exploitation formation water, performing perforation fracturing operation on a hydrate reservoir 24 underlying the horizontal section of the exploitation well 13, and forming a high diversion channel for communicating the horizontal section of the exploitation well 13 with the hydrate reservoir 24 of the horizontal section of the gas injection well 14.
A production casing is run in the production well 13 and natural gas and residual carbon dioxide gas are extracted.
And (4) putting a production casing pipe in the exploitation well 13, and extracting natural gas and residual carbon dioxide gas obtained after the replacement reaction.
Further, the combined production device 10 further includes a first gas-liquid separation storage device 15 disposed on the production platform 11, a first gas storage tank 16 disposed on the production platform 11 and communicated with the first gas-liquid separation storage device 15, a hydraulic perforation fracturing device 17 disposed on the production platform 11, and a liquid storage heating device 18 disposed on the production platform 11 and communicated with the hydraulic perforation fracturing device 17.
Further, the combined mining apparatus 10 further includes a second gas-liquid separation storage device 19 disposed on the injection platform 12, a second gas storage tank 20 disposed on the injection platform 12 and communicated with the second gas-liquid separation storage device 19, a perforation and fracturing combined equipment 21 disposed on the injection platform 12, and a liquid storage tank 22 disposed on the injection platform 12 and communicated with the second gas-liquid separation storage device 19.
The first gas-liquid splitting storage device and the second gas-liquid splitting storage device are used for gas-liquid splitting of the mined natural gas-liquid mixture. The first and second gas tanks 16 and 20 are each used to store produced natural gas. The hydraulic perforation fracturing apparatus 17 is used to inject support material 25, hot seawater and produced formation water into the production string and the directional hydraulic perforation fracturing tool, and the reservoir heating apparatus 18 is used to provide hot seawater to the hydraulic perforation fracturing apparatus 17. Further, it functions to support the formation by injecting the support material 25.
The perforation and fracturing combined equipment 21 is used for injecting carbon dioxide thermal medium into the perforation and fracturing combined tool, and the liquid storage tank 22 is used for storing extracted liquid mixture such as formation water.
In addition, in the present invention, unless otherwise expressly specified or limited, the terms "connected," "stacked," and the like are to be construed broadly, e.g., as meaning permanently connected, detachably connected, or integrally formed; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A method of consolidated natural gas hydrate production, the method comprising:
well cementation: the method comprises the following steps of constructing an offshore mining platform and an injection platform, and respectively arranging a mining well connected with the mining platform and a gas injection well connected with the injection platform, wherein the horizontal section of the mining well is arranged at the junction position of an upper cover layer and a hydrate reservoir layer, and the horizontal section of the gas injection well is arranged in the hydrate reservoir layer and is positioned below the horizontal section of the mining well;
fracturing a gas injection well: putting a perforation and fracturing combined tool under the gas injection well, injecting carbon dioxide hot medium to perform perforation and fracturing operation on the horizontal section of the gas injection well, and performing replacement reaction on the gas injection well after soaking;
fracturing a production well: a production pipe column and a directional hydraulic perforation fracturing tool are put into the exploitation well, a support material, hot seawater and exploited formation water are injected into the production pipe column, perforation fracturing operation is carried out on a hydrate reservoir layer under the exploitation well, and a high diversion channel is formed and is used for communicating the hydrate reservoir layer between the horizontal section of the exploitation well and the horizontal section of the gas injection well;
an extraction step: and (4) putting a production casing under the exploitation well, and extracting natural gas and residual carbon dioxide gas.
2. The well-stabilized natural gas hydrate co-production method according to claim 1, wherein after the extracting step, the co-production method further comprises:
and opening the gas injection well, and repeating the gas injection well fracturing step, the production well fracturing step and the extraction step until the production is finished.
3. A method of consolidated natural gas hydrate production according to claim 1, wherein the gas injection well horizontal segment is located at two thirds of the hydrate reservoir thickness from top to bottom.
4. The well-stabilized natural gas hydrate co-production method according to claim 1, wherein, prior to the gas injection well fracturing step, the co-production method further comprises:
and (3) a step of pressure reduction mining: and (3) putting a production casing pipe under the gas injection well, carrying out depressurization exploitation, and stopping depressurization exploitation when the pressure of the hydrate reservoir is reduced to below 15% of the phase equilibrium pressure of the methane hydrate corresponding to the temperature of the hydrate reservoir.
5. The method for jointly producing gas hydrates for stabilizing a subterranean formation according to claim 1, wherein the step of fracturing the gas injection well comprises:
putting a perforation and fracturing combined tool under the gas injection well, injecting a carbon dioxide hot medium to perform perforation and fracturing operation on the horizontal section of the gas injection well, and detecting temperature and pressure data of the horizontal section of the gas injection well;
stopping injecting the carbon dioxide heat medium when the temperature and pressure data of the horizontal section of the gas injection well reaches the phase equilibrium condition generated by the carbon dioxide hydrate;
and (4) carrying out replacement reaction by gas injection well soaking.
6. A method for consolidated natural gas hydrate joint production according to claim 5, wherein the production well fracturing step specifically comprises:
when the temperature pressure data of the horizontal section of the gas injection well reaches the critical phase balance condition of methane hydrate generation, a production pipe column and a directional hydraulic perforation fracturing tool are put into the exploitation well, supporting materials, hot seawater and exploited formation water are injected into the production pipe column, perforation fracturing operation is carried out on a hydrate reservoir layer under the exploitation well, and a high diversion channel is formed and used for communicating the hydrate reservoir layer between the horizontal section of the exploitation well and the horizontal section of the gas injection well.
7. The stratigraphically stabilized natural gas hydrate cogeneration method according to any one of claims 1-6, wherein said carbon dioxide thermal medium comprises one or more of gaseous carbon dioxide, liquid carbon dioxide, emulsion carbon dioxide, supercritical carbon dioxide, or a carbon dioxide gas mixture.
8. A natural gas hydrate combined exploitation device for stabilizing a stratum is characterized by comprising an exploitation platform and an injection platform which are arranged on the sea, an exploitation well connected with the exploitation platform, and a gas injection well connected with the injection platform, wherein the horizontal section of the exploitation well is arranged at the junction position of an upper covering layer and a hydrate reservoir layer, and the horizontal section of the gas injection well is arranged in the hydrate reservoir layer and is positioned below the horizontal section of the exploitation well;
the combined mining apparatus further comprises:
the perforation and fracturing combined tool is used for putting into the gas injection well and injecting carbon dioxide heat medium to carry out perforation and fracturing operation on the horizontal section of the gas injection well;
the production pipe column and the directional hydraulic perforation fracturing tool are used for descending into the production well, injecting a supporting material, hot seawater and produced formation water into the production pipe column, carrying out perforation fracturing operation on a hydrate reservoir layer under the production well, and forming a high diversion channel for communicating the hydrate reservoir layer between the horizontal section of the production well and the horizontal section of the gas injection well;
and the production casing is used for descending into the production well and extracting natural gas and residual carbon dioxide gas.
9. The stratospherically stabilized natural gas hydrate cogeneration apparatus of claim 8 further comprising a first gas-liquid separation storage device disposed on said production platform, a first gas storage tank disposed on said production platform and in communication with said first gas-liquid separation storage device, a hydraulic perforation fracturing device disposed on said production platform, a reservoir heating device disposed on said production platform and in communication with said hydraulic perforation fracturing device.
10. The stratospherically stabilized natural gas hydrate cogeneration apparatus of claim 8 or 9, further comprising a second gas-liquid separation storage device disposed on said injection platform, a second gas storage tank disposed on said injection platform in communication with said second gas-liquid separation storage device, a perforation and fracturing cogeneration apparatus disposed on said injection platform, and a liquid storage tank disposed on said injection platform in communication with said second gas-liquid separation storage device.
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