CN112127852A - Efficient argillaceous powder sand mold natural gas hydrate exploitation system and exploitation method thereof - Google Patents
Efficient argillaceous powder sand mold natural gas hydrate exploitation system and exploitation method thereof Download PDFInfo
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
- C09K8/66—Compositions based on water or polar solvents
- C09K8/665—Compositions based on water or polar solvents containing inorganic compounds
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
- C09K8/66—Compositions based on water or polar solvents
- C09K8/68—Compositions based on water or polar solvents containing organic compounds
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
- E21B43/295—Gasification of minerals, e.g. for producing mixtures of combustible gases
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
- E21B43/30—Specific pattern of wells, e.g. optimizing the spacing of wells
- E21B43/305—Specific pattern of wells, e.g. optimizing the spacing of wells comprising at least one inclined or horizontal well
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/34—Arrangements for separating materials produced by the well
Abstract
The invention relates to a high-efficiency argillaceous powder sand type natural gas hydrate exploitation system and an exploitation method thereof, belonging to the field of natural gas hydrate exploitation, and comprising an offshore floating platform, a slurry stirring module, a reaction production module and a product collection module.
Description
Technical Field
The invention belongs to the technical field of natural gas hydrate exploitation, and particularly relates to a high-efficiency argillaceous silt type natural gas hydrate exploitation system and an exploitation method thereof.
Background
The natural gas hydrate is a cage-shaped structural substance formed by gathering small-molecule natural gas such as methane and the like and water under the conditions of low temperature and high pressure. It is similar in appearance to ice and can burn, also known as "combustible ice". Compared with other conventional and unconventional oil and gas resources, the natural gas hydrate has the following advantages: high energy density, 1m in standard state3Can release 164m of solid natural gas hydrate3The energy density of the methane is 2-5 times that of natural gas and 10 times that of coal; the distribution range is wide, the natural gas hydrate is widely existed in land frozen soil areas and marine sediments in various parts of the world, and most oceans in the world can meet the phase equilibrium condition of the hydrate; the resource reserve is large, and the total amount of the global natural gas hydrate resources is 2.1 multiplied by 1016m3The organic carbon content is about 2 times of the total amount of the proven fossil energy, and the natural gas hydrate in the sea area of China is predicted to be about 1094 million tons of oil equivalent, wherein the south sea accounts for 80 percent; the buried depth is shallow, the natural gas hydrate is mainly buried in marine sediments with the water depth of more than 300 and the depth of 0-1500m below the sea bottom surface, and the drilling depth is shallow; the natural gas hydrate is clean and pollution-free, the gas released after the natural gas hydrate is decomposed is mainly light hydrocarbon gas such as methane, and the combustion products are water and carbon dioxide, so that the environmental pollution is avoided. Therefore, natural gas hydrate is regarded as "the most potential new energy source in the 21 st century".
At present, the exploitation technology of natural gas hydrate mainly comprises a depressurization method, a thermal excitation method, a chemical inhibitor method and CO2Substitution method. The depressurization method is a method of reducing the pressure at the wellhead by pumping underground water or gas lift to lower the pore pressure near the wellhead and decompose the hydrate. However, with the separation of natural gas hydratesAnd the temperature of the stratum is reduced, so that the pores are frozen or secondary natural gas hydrate is formed, a permeation path is blocked, the gas production rate and the gas production rate are seriously influenced, and the comprehensive exploitation efficiency is reduced. Thermal activation refers to a process in which hydrates are decomposed by raising the temperature of the wellhead or formation. However, the heat loss is large, heat is transferred to the overburden and the underburden while the reservoir is heated, and the high heat injection cost makes the heat loss not practical. The chemical inhibitor method is a method of injecting a hydrate inhibitor (methanol, ethanol, brine, etc.) near a wellhead to decompose the hydrate. However, the method has slow effect, high cost and great harm to environment pollution. CO 22The displacement method is by CO injection2The methane in the hydrate is displaced, and the released heat can provide energy for the decomposition of the methane hydrate, and finally the hydrate is promoted to be decomposed. However, the method has complex process and is difficult to implement. At present, natural gas hydrate exploitation projects of nearly 10 times are successively developed in Canada, America, Japan and China, wherein the problems of low gas production, small exploitation range, short stable production time and the like mostly occur, and the way of commercial exploitation is still heavy and far.
In conclusion, compared with a thermal excitation method, a chemical inhibitor method and CO, the argillaceous powder sand mold natural gas hydrate widely existing in south China sea2In terms of the displacement method, the pressure reduction principle and the process are relatively simple and have practical significance. If the problem of long-term effect of the method can be solved, namely, the reservoir can maintain a good gas-water seepage rate in the whole exploitation process, the method can be widely applied to the exploitation work of the natural gas hydrate. Aiming at the depressurization method, related researchers provide various methods for enhancing the mining effect, but the thinking has some problems: for example, a method for reforming a marine argillaceous silt type natural gas hydrate reservoir by a foam grouting method is described in application number 2018100545815, foam grouting is adopted, but the condition that foam cannot be foamed under an actual high-pressure working condition is ignored; also for example "method for improving the production efficiency of natural gas hydrates using fracturing fluids containing antiswelling agents", see for example patent No. 2009102723926, although it is contemplated that antiswelling agents may be added to ensure that the reservoir remains in the production processThe method has certain gas-water seepage capability, but adopts a fracturing method which is relatively not suitable for a muddy silt type reservoir environment in a production mode, and a fracture channel cannot be formed in the fracturing of a non-diagenetic muddy silt type reservoir. If a new device and a new technical scheme can be further invented to solve the problems, the exploitation efficiency of the natural gas hydrate can be effectively improved.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a high efficiency exploitation system for argillaceous sand-powder type natural gas hydrates, which is used to solve the problem of long-term effectiveness of exploiting argillaceous sand-powder type natural gas hydrates by a depressurization method.
The invention also aims to provide a high-efficiency method for exploiting the argillaceous powder sand mould natural gas hydrate.
A high-efficient argillaceous powder sand mould natural gas hydrate exploitation system includes: the system comprises an offshore floating platform, a slurry stirring module, a reaction production module and a product collection module, wherein the slurry stirring module and the product collection module are positioned on the offshore floating platform floating on the sea surface and are connected through the reaction production module;
the offshore floating platform is connected with the seabed through an anchor cable, so that the position stability of the offshore floating platform is ensured;
the slurry stirring module comprises a type I base fluid storage tank, a type II base fluid storage tank, a type I additive fluid storage tank, a type II additive fluid storage tank, a type A slurry stirrer, a type B slurry stirrer, a type A slurry storage tank, a type B slurry storage tank, a type A slurry pump, a type B slurry pump, a slurry injector, a slurry central injection channel and a slurry annular injection channel;
the liquid outlets of the I-type base liquid storage tank and the I-type additive liquid storage tank are communicated with a liquid inlet of the A-type slurry stirrer, a liquid outlet of the A-type slurry stirrer is communicated with a liquid inlet of the A-type slurry storage tank, a liquid outlet of the A-type slurry storage tank is communicated with a liquid inlet of an A-type slurry pump, a liquid outlet of the A-type slurry pump is communicated with a liquid inlet of a grouting machine, and a liquid outlet of the grouting machine is communicated with an A-type slurry annulus injection channel of a slurry injection device; the A-type slurry annulus injection channel is an annular cavity formed between the well wall casing and the outer wall of a B-type slurry central injection channel of the slurry injection device;
the liquid outlets of the II-type base liquid storage tank and the II-type additive liquid storage tank are communicated with the liquid inlet of a B-type slurry stirrer, the liquid outlet of the B-type slurry stirrer is communicated with the liquid inlet of a B-type slurry storage tank, the liquid outlet of the B-type slurry storage tank is communicated with the liquid inlet of a B-type slurry pump, the liquid outlet of the B-type slurry pump is communicated with the liquid inlet of a B-type slurry injector, and the liquid outlet of the B-type slurry injector is communicated with a central B-type slurry injection channel of a slurry injection device;
the reaction production module comprises a slurry conveying pipeline, a horizontal perforation device, an upper horizontal production casing, a lower horizontal production casing, an upper pressure reduction water pump and a lower pressure reduction water pump, wherein an A-type slurry annular injection channel in the slurry conveying pipeline is communicated with an A-type slurry annular injection channel of the slurry injection device, and a B-type slurry central injection channel in the slurry conveying pipeline is communicated with a B-type slurry central injection channel of the slurry injection device; the B-type slurry central injection channel in the slurry conveying pipeline refers to an annular cavity formed between the outer wall of the B-type slurry central conveying channel in the slurry conveying pipeline and a well wall sleeve, the lower ends of an A-type slurry annular injection channel and the B-type slurry central injection channel in the slurry conveying pipeline are connected with a horizontal perforating device through a non-return device, an upper horizontal production casing and a lower horizontal production casing are respectively arranged in natural gas hydrate storage layers on the upper side and the lower side of the horizontal perforating device, the upper horizontal production casing is communicated with a product conveying pipeline through an upper pressure reducing water pump, and the lower horizontal production casing is communicated with the product conveying pipeline through a lower pressure reducing water pump; a plurality of through holes penetrating into the upper horizontal production sleeve and the lower horizontal production sleeve are distributed on the upper horizontal production sleeve and the lower horizontal production sleeve;
the horizontal perforation device comprises an inner sleeve, an outer sleeve and a transposition push rod, the transposition push rod is fixedly connected to the inner wall of the outer sleeve, the extension end of the transposition push rod is fixedly connected with the inner sleeve and can drive the inner sleeve to do axial telescopic movement in the outer sleeve, through center perforations which are mutually matched are arranged on the inner sleeve and the outer sleeve, the lower end of a B-type slurry center injection channel in the slurry conveying pipeline is communicated with the outer sleeve, the lower end of an A-type slurry annular injection channel in the slurry conveying pipeline is communicated with an annular cavity formed between the outer wall of the outer sleeve and a well wall sleeve, the product collection module comprises a product conveying pipeline, a filter, a gas-liquid separation device and a natural gas storage tank, the upper end of the product conveying pipeline is communicated with a gas-liquid separation device; and a plurality of through holes are distributed on the well wall sleeve outside the outer sleeve.
A high-efficiency mining method of argillaceous powder sand mold natural gas hydrate comprises the following steps:
fixing an offshore floating platform on the sea level through an anchor rope in a natural gas hydrate enrichment area, arranging a finished slurry stirring module and a finished product collecting module on the offshore floating platform, penetrating a horizontal perforating device through a natural gas hydrate overlying stratum, and descending into a natural gas hydrate reservoir stratum, and respectively penetrating an upper horizontal production casing and a lower horizontal production casing through the natural gas hydrate overlying stratum to respectively descend to the upper side and the lower side of the horizontal perforating device in a double-horizontal-well mode;
injecting the I-type base liquid in the I-type base liquid storage tank and the I-type additive liquid in the I-type additive liquid storage tank into an A-type slurry stirrer on a slurry stirring module, mixing for a certain time until the viscosity of the mixed slurry is 1500mPa & s, injecting the mixed slurry into an A-type slurry storage tank, injecting the II-type base liquid in the II-type base liquid storage tank and the II-type additive liquid in the II-type additive liquid storage tank into a B-type slurry stirrer, mixing for a certain time until the viscosity of the mixed slurry is 1500mPa & s, and injecting the mixed slurry into a B-type slurry storage tank; the method comprises the following steps that an A-type slurry storage tank injects A-type slurry into an A liquid inlet of a grouting machine through an A-type slurry mud pump, and a B-type slurry storage tank injects B-type slurry into a B liquid inlet of the grouting machine through a B-type slurry mud pump, wherein the I-type base fluid and the II-type base fluid are sodium silicate solution or silicate slurry simultaneously, the grouting machine injects the A-type slurry into an annular cavity between an outer sleeve and a well wall sleeve through an A-type slurry annulus injection channel of a slurry injection device, N is greater than 5 after the liquid column pressure in the A-type slurry annulus injection channel reaches N MPa, the A-type slurry in the annular cavity between the outer sleeve and the well wall sleeve is split towards the interior of a natural gas hydrate reservoir under the action of the internal liquid column pressure, and the liquid column pressure in the A-type slurry annulus injection channel is always kept at N MPa and N is greater than; when the internal pressure of the natural gas hydrate reservoir tends to be stable, the electric control transposition push rod drives the inner sleeve to move downwards, the central perforation channels of the inner sleeve and the outer sleeve are communicated in a matching mode, B-type slurry is injected into the inner sleeve through the B-type slurry central injection channel of the slurry injection device by the slurry injection machine, the liquid column pressure in the B-type slurry central injection channel is N +2MPa, N is greater than 5, and the B-type slurry in the inner sleeve is subjected to secondary splitting towards the natural gas hydrate reservoir in a radial mode through the central perforation;
and step four, starting the upper pressure reducing water pump and the lower pressure reducing water pump to form a negative pressure area in the splitting area, decomposing the natural gas hydrate under the condition of pressure reduction, conveying decomposed products to a filter and a gas-liquid separation device through a product collecting channel, collecting the decomposed natural gas hydrate products into a gas storage tank, and restarting the next working cycle when the gas output rate is lower than a preset value.
In the second step, the type i additive solution is an inorganic ammonium chloride solution with a concentration of 3-8%, a poly-dimethyldiallylammonium chloride solution, a poly-trimethylallylammonium chloride solution, a dimethyldiallylammonium chloride solution or a trimethylallylammonium chloride solution, and the type ii additive solution is a sodium nitrite solution or a potassium nitrite solution with a concentration of 3-8%.
Furthermore, in the second step, the pressure of the liquid column in the A-type slurry in the annular cavity between the outer sleeve and the well wall sleeve is always kept at N MPa, wherein N is more than 5.
Furthermore, in the second step, the pressure of the liquid column of the B-type slurry in the inner sleeve is always kept at N +2MPa, and N is greater than 5 in the splitting process.
Furthermore, when the B-type slurry in the inner sleeve in the second step is subjected to secondary fracturing to the natural gas hydrate reservoir in a radial manner through the central perforation, the natural gas hydrate reservoir is fractured when the A-type slurry and the B-type slurry are mixed.
The invention has the beneficial effects that:
1. the invention adopts A-type and B-type slurry to improve the connectivity of the muddy silt type natural gas hydrate reservoir, widens the gas-water seepage channels in the reservoir, enhances the gas-water seepage capability, ensures that the reservoir can maintain better gas-water seepage rate in the process of depressurizing and exploiting the natural gas hydrate, and solves the problem of long-term effect of the depressurization method, thereby efficiently developing the natural gas hydrate.
2. According to the method, the base liquid is adopted to split the argillaceous powder sand mold natural gas hydrate reservoir, so that on one hand, the internal connectivity of the natural gas hydrate reservoir can be improved, the gas-water seepage capability of the natural gas hydrate reservoir can be improved, and the depressurization decomposition range of the natural gas hydrate can be expanded; on the other hand, the mechanical stability of the interior of the natural gas hydrate reservoir can be maintained, the stability of the internal stress state of the reservoir in the whole exploitation process is guaranteed, and certain avoidance effect is achieved on marine geological disasters such as seabed landslide and collapse.
3. After the type I base liquid and the type I additive liquid are mixed and injected into the natural gas hydrate reservoir, on one hand, the thickness of a hydration film after hydration reaction of clay particles is reduced, and the influence of the reduction of the seepage capability of the natural gas hydrate reservoir due to the hydration expansion effect of clay in a argillaceous silt reservoir is reduced; on the other hand, the decomposition of the natural gas hydrate in the natural gas hydrate reservoir can be promoted, the exploitation range is expanded, and the generation of secondary hydrate in the depressurization exploitation process is inhibited.
4. After the II-type base liquid additive liquid and the II-type base liquid are mixed and injected into the natural gas hydrate reservoir, secondary splitting can be performed on the natural gas hydrate reservoir, the splitting length and the splitting radius are enlarged, and the internal reaction area of the natural gas hydrate reservoir is enlarged; meanwhile, when the A-type slurry and the B-type slurry are gradually mixed, the temperature of a natural gas hydrate reservoir is increased, the phase equilibrium state of the natural gas hydrate is broken, and the decomposition of the natural gas hydrate in the splitting area is promoted; promoting the molecular thermal motion, increasing the reaction contact area of the A-type slurry and the B-type slurry, and enlarging the reaction area; a large amount of gas is released, the natural gas hydrate reservoir can be fractured, a seepage passage in the natural gas hydrate reservoir is expanded, and the connectivity inside the natural gas hydrate reservoir is enhanced; the generated gas can generate bubbles in the base fluid slurry to form pores, and after the slurry consolidation body is formed, the internal pores stably exist and can be used as seepage channels for producing gas.
5. The invention has simple reaction principle, less complicated engineering process, low cost and capacity of meeting the requirement of mining industry on high efficiency, economy and safety.
Drawings
Fig. 1 is an overall schematic view of the present invention.
Figure 2 is a schematic diagram of the center perforation penetration of the horizontal perforating device of the present invention.
FIG. 3 is a schematic diagram of the staggered closing of the central perforations of the horizontal perforating device of the present invention.
Detailed Description
Referring to fig. 1 to 3, a high-efficiency production system for argillaceous powder sand type natural gas hydrates includes: the system comprises an offshore floating platform 2, a slurry stirring module, a reaction production module and a product collection module, wherein the slurry stirring module and the product collection module are positioned on the offshore floating platform 2 floating on the sea surface and are connected through the reaction production module;
the offshore floating platform 2 is connected with the seabed through an anchor cable 18, so that the position stability of the offshore floating platform is ensured;
the slurry stirring module comprises a type I base liquid storage tank 3-2, a type II base liquid storage tank 3-1, a type I additive liquid storage tank 4-2, a type II additive liquid storage tank 4-1, a type A slurry stirrer 5-2, a type B slurry stirrer 5-1, a type A slurry storage tank 6-2, a type B slurry storage tank 6-1, a type A slurry pump 7-2, a type B slurry pump 7-1, a slurry injector 8, a slurry central injection channel 9-1 and a slurry annulus injection channel 9-2;
the liquid outlets of the I-type base liquid storage tank 3-2 and the I-type additive liquid storage tank 4-2 are communicated with the liquid inlet of an A-type slurry stirrer 5-2, the liquid outlet of the A-type slurry stirrer 5-2 is communicated with the liquid inlet of an A-type slurry storage tank 6-2, the liquid outlet of the A-type slurry storage tank 6-2 is communicated with the liquid inlet of an A-type slurry pump 7-2, the liquid outlet of the A-type slurry pump 7-2 is communicated with the liquid inlet A of a slurry injector 8, and the liquid outlet A of the slurry injector 8 is communicated with an A-type slurry annulus injection channel 9-2 of a slurry injector; the A-type slurry annular injection channel 9-2 is an annular cavity formed between the well wall casing and the outer wall of a B-type slurry central injection channel 9-1 of the slurry injection device;
the liquid outlets of the II-type base liquid storage tank 3-1 and the II-type additive liquid storage tank 4-1 are communicated with the liquid inlet of a B-type slurry stirrer 5-1, the liquid outlet of the B-type slurry stirrer 5-1 is communicated with the liquid inlet of a B-type slurry storage tank 6-1, the liquid outlet of the B-type slurry storage tank 6-1 is communicated with the liquid inlet of a B-type slurry pump 7-1, the liquid outlet of the B-type slurry pump 7-1 is communicated with the liquid inlet B of a slurry injector 8, and the liquid outlet B of the slurry injector 8 is communicated with a B-type slurry central injection channel 9-1 of a slurry injector;
the reaction production module comprises a slurry conveying pipeline 10, a horizontal perforating device 11, an upper horizontal production casing 12-1, a lower horizontal production casing 12-2, an upper pressure-reducing water pump 13-1 and a lower pressure-reducing water pump 13-2, wherein an A-type slurry annular injection channel in the slurry conveying pipeline 10 is communicated with an A-type slurry annular injection channel 9-2 of the slurry injection device, and a B-type slurry central injection channel in the slurry conveying pipeline 10 is communicated with a B-type slurry central injection channel 9-1 of the slurry injection device; the B-type slurry central injection channel in the slurry conveying pipeline 10 refers to an annular cavity formed between the outer wall of the B-type slurry central conveying channel in the slurry conveying pipeline 10 and a well wall sleeve, the lower ends of an A-type slurry annular injection channel and the B-type slurry central injection channel in the slurry conveying pipeline 10 are connected with a horizontal perforating device 11 through a non-return device 23, an upper horizontal production casing 12-1 and a lower horizontal production casing 12-2 are respectively arranged in natural gas hydrate reservoir beds 20 on the upper side and the lower side of the horizontal perforating device 11, the upper horizontal production casing 12-1 is communicated with a product conveying pipeline 14 through an upper pressure reduction water pump 13-1, and the lower horizontal production casing 12-2 is communicated with the product conveying pipeline 14 through a lower pressure reduction water pump 13-2; a plurality of through holes penetrating into the upper horizontal production casing 12-1 and the lower horizontal production casing 12-2 are distributed on the upper horizontal production casing 12-1 and the lower horizontal production casing 12-2;
the horizontal perforating device 11 comprises an inner sleeve 1101, an outer sleeve 1102 and a transposition push rod 1103, the transposition push rod 1103 is fixedly connected with the inner wall of the outer sleeve 1102, the extension end of the transposition push rod 1103 is fixedly connected with the inner sleeve 1101 and can drive the inner sleeve 1101 to do axial telescopic motion in the outer sleeve 1102, through central perforations which are mutually matched are arranged on the inner sleeve 1101 and the outer sleeve 1102, the lower end of a B-type slurry central injection channel in a slurry conveying pipeline 10 is communicated with the outer sleeve 1102, the lower end of an A-type slurry annular injection channel in the slurry conveying pipeline 10 is communicated with an annular cavity formed between the outer wall of the outer sleeve 1102 and a well, the product collection module comprises a product conveying pipeline 14, a filter 15, a gas-liquid separation device 16 and a natural gas storage tank 17, the upper end of the product conveying pipeline 14 is communicated with a separation inlet of the gas-liquid separation device 16 through the filter 15, and a separation outlet of the gas-liquid separation device 16 is communicated with the natural gas storage tank 17 and a gas storage inlet; a plurality of through holes are distributed on the well wall sleeve outside the outer sleeve 1102.
A high-efficiency mining method of argillaceous powder sand mold natural gas hydrate comprises the following steps:
firstly, in a natural gas hydrate enrichment area, an offshore floating platform 2 is fixed on the sea level 1 through an anchor rope 18, a slurry stirring module and a product collecting module are arranged on the offshore floating platform 2, a deep sea directional drilling technology is applied to enable a horizontal perforation device 11 to penetrate through a natural gas hydrate overlying stratum 19 and to be lowered into a natural gas hydrate reservoir stratum 20, and an upper horizontal production casing 12-1 and a lower horizontal production casing 12-2 respectively penetrate through the natural gas hydrate overlying stratum 19 and are lowered into the upper side and the lower side of the horizontal perforation device 11 in a double horizontal well mode;
injecting the I-type base solution in the I-type base solution storage tank 3-2 and the I-type additive solution in the I-type additive solution storage tank 4-2 into an A-type slurry stirrer 5-2 on a slurry stirring module, and mixing for a certain time until the viscosity of the mixed slurry is 1500mPa & s, and injecting the mixed slurry into an A-type slurry storage tank 6-2; simultaneously, injecting the II-type base solution in the II-type base solution storage tank 3-1 and the II-type additive solution in the II-type additive solution storage tank 4-1 into a B-type slurry stirrer 5-1 for mixing for a certain time, and injecting the mixed slurry into a B-type slurry storage tank 6-1 when the viscosity of the mixed slurry is 1500mPa & s; the A type slurry storage tank 6-2 injects A type slurry into an A liquid inlet of a grouting machine 8 through an A type slurry pump 7-2, the B type slurry storage tank 6-1 injects B type slurry into a B liquid inlet of the grouting machine 8 through a B type slurry pump 7-1, wherein the I type base fluid and the II type base fluid are sodium silicate solution or silicate slurry at the same time, the I type additive fluid can use inorganic ammonium chloride solution with 3-8% concentration, poly-dimethyl diallyl ammonium chloride solution, poly-trimethyl allyl ammonium chloride solution, dimethyl diallyl ammonium chloride solution or trimethyl allyl ammonium chloride solution, the II type additive fluid can use sodium nitrite solution and potassium nitrite solution with 3-8% concentration, and the central perforations on the inner sleeve 1101 and the outer sleeve 1102 of the horizontal perforation device 11 are staggered with each other initially, at the moment, the grouting machine 8 injects A-type slurry into an annular cavity between the outer sleeve 1102 and the well wall casing through an A-type slurry annular injection channel 9-2 of the slurry injection device, N is greater than 5 after the pressure of a liquid column in the A-type slurry annular injection channel 9-2 reaches N MPa, the A-type slurry in the annular cavity between the outer sleeve 1102 and the well wall casing is split towards the inside of the natural gas hydrate reservoir 20 under the action of the pressure of the internal liquid column, and the pressure of the liquid column in the A-type slurry annular injection channel 9-2 is always kept at N MPa and N is greater than 5 in the splitting process; on one hand, the I-type additive solution is rich in active metal cations and can effectively exchange with the metal cations among the clay particles, so that the thickness of a hydrated film after hydration reaction of the clay particles is reduced, and the influence of the reduction of the seepage capability of a argillaceous silty sand reservoir due to the hydration expansion effect of the clay is reduced; on the other hand, the I-type additive liquid is used as a natural gas hydrate inhibitor, which can promote the decomposition of natural gas hydrate in a natural gas hydrate reservoir 20, expand the exploitation range, inhibit the generation of secondary hydrate in the depressurization exploitation process, avoid the blockage of a permeation path due to the generation of the secondary hydrate, monitor the pressure change condition in the natural gas hydrate reservoir 20 in real time, drive the inner sleeve 1101 to move downwards by the electric control transposition push rod 1103 when the internal pressure of the natural gas hydrate reservoir 20 tends to be stable, the central perforation channels of the inner sleeve 1101 and the outer sleeve 1102 are communicated with each other at the moment, simultaneously, the grouting machine 8 injects B-type slurry into the inner sleeve 1101 through the B-type slurry central injection channel 9-1 of the slurry injection device, the liquid column pressure in the B-type slurry central injection channel 9-1 is set to be N +2MPa, and N is greater than, the B-type slurry in the inner sleeve 1101 is subjected to secondary splitting towards the natural gas hydrate reservoir stratum 20 in a radial mode through a central perforation, the flow rates of the A-type slurry and the B-type slurry are uniformly set to be 30L/min, and in a horizontal production well section, the II-type base fluid additive liquid can perform secondary splitting on the natural gas hydrate reservoir stratum 20 while playing a role of a natural gas hydrate inhibitor, so that the splitting length and the splitting radius are enlarged, and the reaction area in the natural gas hydrate reservoir stratum 20 is enlarged; on the other hand, the following chemical reactions will occur when the type a slurry is mixed with the type B slurry:
NH4Cl+NaNO2＝NaCl+2H2O+N2↑ΔH0＝-332.58kj/mol
the reaction is exothermic reaction, the temperature in the natural gas hydrate reservoir 20 can be raised, the phase equilibrium state of the natural gas hydrate is broken, the decomposition of the natural gas hydrate in the splitting area is promoted, meanwhile, the molecular thermal motion is promoted, the reaction contact area of the A-type slurry and the B-type slurry is increased, and the reaction area is enlarged; the reaction can release a large amount of gas at the same time, and then the natural gas hydrate reservoir 20 is fractured, so that a seepage channel in the natural gas hydrate reservoir 20 is enlarged, the connectivity inside the natural gas hydrate reservoir 20 is enhanced, and simultaneously, bubbles can be generated in the base fluid slurry to form pores, and after the slurry consolidation body is formed, the internal pores stably exist and can be used as a seepage channel for producing gas;
and step four, starting the upper pressure reducing water pump 13-1 and the lower pressure reducing water pump 13-2 to form a negative pressure area in the splitting area, decomposing the natural gas hydrate under the condition of pressure reduction, conveying decomposed products to the filter 15 and the gas-liquid separation device 16 through the product collecting channel 14, collecting the decomposed natural gas hydrate products into the gas storage tank 17, and restarting the next working cycle when the gas output rate is lower than a preset value.
In summary, the invention provides an efficient exploitation system of the argillaceous silt and sand type natural gas hydrate and a working method thereof, which can remarkably improve the connectivity inside a reservoir stratum, enhance the gas-water seepage capability and solve the long-acting problem of exploiting the argillaceous silt and sand type natural gas hydrate by a depressurization method, thereby improving the comprehensive exploitation efficiency.
The invention adopts the A-type slurry and the B-type slurry to improve the connectivity of the muddy silt type natural gas hydrate reservoir, widens the gas-water seepage passage in the natural gas hydrate reservoir, enhances the gas-water seepage capability, ensures that the natural gas hydrate reservoir maintains better gas-water seepage rate in the process of depressurizing and exploiting the natural gas hydrate, avoids the generation of ice and secondary hydrate in the seepage passage of the natural gas hydrate reservoir, solves the long-term problem of the depressurization method, and realizes the high-efficiency development of the muddy silt type natural gas hydrate.
Claims (6)
1. The utility model provides a high-efficient argillaceous powder sand mould natural gas hydrate exploitation system which characterized in that: the system comprises an offshore floating platform (2), a slurry stirring module, a reaction production module and a product collection module, wherein the slurry stirring module and the product collection module are positioned on the offshore floating platform (2) floating on the sea surface, and are connected through the reaction production module;
the offshore floating platform (2) is connected with the seabed through an anchor cable (18);
the slurry stirring module comprises a type I base liquid storage tank (3-2), a type II base liquid storage tank (3-1), a type I additive liquid storage tank (4-2), a type II additive liquid storage tank (4-1), a type A slurry stirrer (5-2), a type B slurry stirrer (5-1), a type A slurry storage tank (6-2), a type B slurry storage tank (6-1), a type A slurry pump (7-2), a type B slurry pump (7-1), a slurry injector (8), a slurry central injection channel (9-1) and a slurry annulus injection channel (9-2);
the liquid outlets of the I-type base liquid storage tank (3-2) and the I-type additive liquid storage tank (4-2) are communicated with the liquid inlet of the A-type slurry stirrer (5-2), the liquid outlet of the A-type slurry stirrer (5-2) is communicated with the liquid inlet of the A-type slurry storage tank (6-2), the liquid outlet of the A-type slurry storage tank (6-2) is communicated with the liquid inlet of the A-type slurry pump (7-2), the liquid outlet of the A-type slurry pump (7-2) is communicated with the liquid inlet A of the slurry injector (8), and the liquid outlet A of the slurry injector (8) is communicated with the annular slurry injection channel A (9-2) of the slurry injector;
the liquid outlets of the II-type base liquid storage tank (3-1) and the II-type additive liquid storage tank (4-1) are communicated with the liquid inlet of a B-type slurry stirrer (5-1), the liquid outlet of the B-type slurry stirrer (5-1) is communicated with the liquid inlet of a B-type slurry storage tank (6-1), the liquid outlet of the B-type slurry storage tank (6-1) is communicated with the liquid inlet of a B-type slurry pump (7-1), the liquid outlet of the B-type slurry pump (7-1) is communicated with the liquid inlet B of a slurry injector (8), and the liquid outlet B of the slurry injector (8) is communicated with a central B-type slurry injection channel (9-1) of a slurry injection device;
the reaction production module comprises a slurry conveying pipeline (10), a horizontal perforation device (11), an upper horizontal production casing (12-1), a lower horizontal production casing (12-2), an upper pressure reduction water pump (13-1) and a lower pressure reduction water pump (13-2), wherein an A-type slurry annulus injection channel in the slurry conveying pipeline (10) is communicated with an A-type slurry annulus injection channel (9-2) of the slurry injection device, and a B-type slurry center injection channel in the slurry conveying pipeline (10) is communicated with a B-type slurry center injection channel (9-1) of the slurry injection device; the lower ends of an A-type slurry annular injection channel and a B-type slurry central injection channel in a slurry conveying pipeline (10) are connected with a horizontal perforation device (11) through a non-return device (23), an upper horizontal production casing (12-1) and a lower horizontal production casing (12-2) are respectively arranged in natural gas hydrate reservoirs (20) on the upper side and the lower side of the horizontal perforation device (11), the upper horizontal production casing (12-1) is communicated with a product conveying pipeline (14) through an upper pressure reduction water pump (13-1), and the lower horizontal production casing (12-2) is communicated with the product conveying pipeline (14) through a lower pressure reduction water pump (13-2);
the horizontal perforation device (11) comprises an inner sleeve (1101), an outer sleeve (1102) and a transposition push rod (1103), the transposition push rod (1103) is fixedly connected to the inner wall of the outer sleeve (1102), the extension end of the transposition push rod (1103) is fixedly connected with the inner sleeve (1101) and can drive the inner sleeve (1101) to do axial telescopic movement in the outer sleeve (1102), the inner sleeve (1101) and the outer sleeve (1102) are provided with through central perforations which are matched with each other, the lower end of a B-type slurry central injection channel in a slurry conveying pipeline (10) is communicated with the outer sleeve (1102), and the lower end of an A-type slurry annular injection channel in the slurry conveying pipeline (10) is communicated with an annular cavity formed between the outer wall of the outer sleeve (1102) and a well;
the product collection module comprises a product conveying pipeline (14), a filter (15), a gas-liquid separation device (16) and a natural gas storage tank (17), wherein the upper end of the product conveying pipeline (14) is communicated with a separation inlet of the gas-liquid separation device (16) through the filter (15), and a separation outlet of the gas-liquid separation device (16) is communicated with the natural gas storage tank (17) and the gas storage inlet.
2. A high-efficiency mining method of argillaceous powder sand mold natural gas hydrate is characterized in that: the method comprises the following steps:
in a natural gas hydrate enrichment region, an offshore floating platform (2) is fixed on the sea level (1) through an anchor cable (18), a slurry stirring module and a product collecting module are arranged on the offshore floating platform (2), a horizontal perforating device (11) penetrates through a natural gas hydrate overlying stratum (19) and is lowered into a natural gas hydrate reservoir stratum (20), an upper horizontal production casing (12-1) and a lower horizontal production casing (12-2) respectively penetrate through the natural gas hydrate overlying stratum (19) and are lowered into the upper side and the lower side of the horizontal perforating device (11) in a double-horizontal-well mode;
injecting the I-type base liquid in the I-type base liquid storage tank (3-2) and the I-type additive liquid in the I-type additive liquid storage tank (4-2) into an A-type slurry stirrer (5-2) on a slurry stirring module, and mixing for a certain time until the viscosity of the mixed slurry is 1500mPa & s, and injecting the mixed slurry into an A-type slurry storage tank (6-2); simultaneously, injecting the II-type base solution in the II-type base solution storage tank (3-1) and the II-type additive solution in the II-type additive solution storage tank (4-1) into a B-type slurry stirrer (5-1) for mixing for a certain time, and injecting the mixed slurry into a B-type slurry storage tank (6-1) when the viscosity of the mixed slurry is 1500mPa & s; the A-type slurry storage tank (6-2) injects A-type slurry into an A liquid inlet of the grouting machine (8) through an A-type slurry mud pump (7-2), the B-type slurry storage tank (6-1) injects B-type slurry into a B liquid inlet of the grouting machine (8) through a B-type slurry mud pump (7-1), the I-type base fluid and the II-type base fluid are simultaneously sodium silicate solution or silicate slurry, the grouting machine (8) injects the A-type slurry into an annular cavity between the outer sleeve (1102) and the well wall sleeve through an A-type slurry annulus injection channel (9-2) of the slurry injection device, N is greater than 5 after the liquid column pressure in the A-type slurry annulus injection channel (9-2) reaches N MPa, and the A-type slurry in the annular cavity between the outer sleeve (1102) and the well wall sleeve is split towards the interior of the natural gas hydrate reservoir (20) under the action of the internal liquid column pressure, in the splitting process, the liquid column pressure in the A-type slurry annular injection channel (9-2) is always kept at N MPa, N is more than 5, when the internal pressure of the natural gas hydrate reservoir (20) tends to be stable, the electric control transposition push rod (1103) drives the inner sleeve (1101) to move downwards, the central perforation channels of the inner sleeve (1101) and the outer sleeve (1102) are communicated in a matching mode, meanwhile, the grouting machine (8) injects B-type slurry into the inner sleeve (1101) through the B-type slurry central injection channel (9-1) of the slurry injection device, the liquid column pressure in the B-type slurry central injection channel (9-1) is set to be N +2MPa, N is more than 5, and the B-type slurry in the inner sleeve (1101) is split towards the natural gas hydrate reservoir (20) in a radial mode through the central perforation channel;
and fourthly, starting an upper pressure reducing water pump (13-1) and a lower pressure reducing water pump (13-2) to form a negative pressure area in the splitting area, decomposing the natural gas hydrate under the condition of pressure reduction, conveying decomposed products to a filter (15) and a gas-liquid separation device (16) through a product collecting channel (14), collecting the decomposed natural gas hydrate products into a gas storage tank (17), and restarting the next working cycle when the gas output rate is lower than a preset value.
3. The efficient argillaceous powder sand mold natural gas hydrate exploitation method according to claim 2, wherein the method comprises the following steps: in the second step, the I type additive solution is an inorganic ammonium chloride solution with the concentration of 3-8%, a poly dimethyl diallyl ammonium chloride solution, a poly trimethyl allyl ammonium chloride solution, a dimethyl diallyl ammonium chloride solution or a trimethyl allyl ammonium chloride solution, and the II type additive solution is a sodium nitrite solution or a potassium nitrite solution with the concentration of 3-8%.
4. The efficient argillaceous powder sand mold natural gas hydrate exploitation method according to claim 2, wherein the method comprises the following steps: in the second step, the pressure of the liquid column in the A-type slurry in the annular cavity between the outer sleeve (1102) and the well wall sleeve is always kept at N MPa, wherein N is more than 5.
5. The efficient argillaceous powder sand mold natural gas hydrate exploitation method according to claim 2, wherein the method comprises the following steps: and in the second step, the pressure of the liquid column in the B-type slurry in the inner sleeve (1101) is always kept at N +2MPa, and N is greater than 5 in the splitting process.
6. The efficient argillaceous powder sand mold natural gas hydrate exploitation method according to claim 2, wherein the method comprises the following steps: and in the second step, when the B-type slurry in the inner sleeve (1101) is subjected to secondary fracturing to the natural gas hydrate reservoir (20) in a radial mode through the central perforation, the natural gas hydrate reservoir is fractured when the A-type slurry and the B-type slurry are mixed.
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| CN114183115A (en) * | 2021-12-07 | 2022-03-15 | 中国矿业大学 | Efficient natural gas hydrate exploitation system and method |
| WO2022237777A1 (en) * | 2021-05-12 | 2022-11-17 | 南方科技大学 | Method for reinforcing natural gas hydrate reservoir |
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| WO2022237777A1 (en) * | 2021-05-12 | 2022-11-17 | 南方科技大学 | Method for reinforcing natural gas hydrate reservoir |
| CN114183115A (en) * | 2021-12-07 | 2022-03-15 | 中国矿业大学 | Efficient natural gas hydrate exploitation system and method |
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