CN114458264A - Oil shale in-situ mining reaction area control system and process method - Google Patents
Oil shale in-situ mining reaction area control system and process method Download PDFInfo
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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
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
- E21B43/241—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection combined with solution mining of non-hydrocarbon minerals, e.g. solvent pyrolysis of oil shale
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Abstract
A control system and a process method for an oil shale in-situ mining reaction area belong to the field of oil shale in-situ mining, the system comprises a well network system, a heating system and a ground gas injection system, the process method comprises a drying preheating stage, a high-temperature heating stage, a reverse gas injection self-heating stage, a normal-temperature reverse gas injection self-heating stage and a high-pressure displacement stage, the reverse gas injection process method provided by the invention can effectively solve the problems that the viscosity of shale oil and asphaltene is increased due to large heat loss along the underground oil gas migration, so that a seepage migration channel blocks cementing, the temperature, the pressure and the gas flow of the reverse gas injection process method are stable and adjustable, the stable forward expansion of the oil shale formation self-heating reaction can be ensured, the phenomenon of cementing can not occur under the condition of residual heat in a high-permeability reaction complete area of the mining shale oil gas product, and is particularly suitable for long-well distance underground unconventional energy in-situ mining, the process method has the advantages of short construction period, less underground accidents, strong construction operability and controllable reaction rate of the reaction zone.
Description
Technical Field
The invention relates to the field of oil shale in-situ mining, in particular to a control system and a process method for an oil shale in-situ mining reaction area.
Background
Along with the gradual increase of the exploration and development of resources such as oil shale oil, shale oil gas, oil-rich coal, oil sand, coal bed gas and the like in recent years, the continuous discovery of unconventional energy sources, the resource exploration reserve of the unconventional energy sources is increasing year by year, and the exploitation and application prospect is wide.
The oil shale in-situ exploitation technology is also called underground in-situ conversion technology, and the technology is to inject a heat carrier medium such as steam and CO into a target reservoir at the surface or underground2，N2And O2And the mining operation of the oil shale target layer is realized. The heat carrier medium is heated to a preset temperature through a heating device, heat exchange is carried out between the heat carrier medium and the oil shale of the target layer in a conduction and convection mode, kerogen organic matters of the oil shale in the target layer reach the cracking temperature, hydrocarbon oil gas products generated by cracking are transported to the ground along with the heat carrier medium and water, and then separation and purification are carried out.
The oil shale is used as a compact oil gas reservoir, the porosity and the permeability are small, the opening degree of a hydraulic fracturing crack formed in the oil shale after the reservoir is transformed is extremely low, the 'national oil shale in-situ cracking pilot test engineering' of Jilin university develops and utilizes the oil shale, the oil shale in-situ conversion exploitation test is accelerated, the Jilin university finds that in the oil shale in-situ exploitation pilot test field of Songliao basin, the influence of the process link of injecting low-temperature nitrogen to dry the stratum in the heating process of the oil shale in the early stage is not great, the injection link of high-temperature nitrogen into the stratum is switched to the process injection link of normal-temperature air, as the heat injection front edge generates a self-heating chemical reaction, a great amount of oil gas products are transported to a production well end through the hydraulic fracture, the heat loss along the process from a heat injection well to the production well is increased rapidly, the temperature of the oil gas products is reduced, the viscosity is increased, the hydraulic fracturing fracture is seriously blocked, and the oil gas coking products with overhigh temperature are generated, the blocking effect is exacerbated and this phenomenon is more pronounced as well spacing increases. Oil and gas abundance of oil shale reservoirs in China is low, and exploitation cost can be obviously reduced by increasing well spacing, so that a feasible oil shale in-situ exploitation reaction zone control process method is explored, construction resistance of an underground exploitation process is reduced, and the method is an important means for realizing the commercial exploitation of unconventional compact reservoirs.
Disclosure of Invention
The purpose of the invention is: in order to solve the problems of the background technology, a control system and a process method for an oil shale in-situ exploitation reaction zone are provided, which are used for solving the problems that the oil and gas products of a target reservoir layer block a seepage channel and the production cost is too high due to too high heat loss in the in-situ exploitation process under the condition of large well spacing.
The technical scheme adopted by the invention for realizing the purpose is as follows: oil shale in situ mining reaction zone control system, its characterized in that includes: a well pattern system, a heating system and a ground gas injection system;
the well pattern system is a regular hexagon seven-point well pattern formed by seven injection and production wells, the well pattern unit consists of six peripheral injection and production wells positioned at six vertexes of the regular hexagon and one central injection and production well positioned at the center of the regular hexagon, the six peripheral injection and production wells form a peripheral injection and production well group, and all the injection and production wells in the well pattern unit are provided with injection and production well heads;
the ground gas injection system comprises a dust remover, an air compressor, a cold dryer, a nitrogen making machine, a three-way valve, a pressure stabilizing tank, a manual ball valve, a supercharger, a first electric valve, a flowmeter, a one-way valve, a temperature sensor, a pressure sensor, a three-channel electric valve, a second electric valve, a third electric valve, a fourth electric valve, a fifth electric valve, a sixth electric valve and a seventh electric valve, wherein the three-channel electric valve is provided with a gas inlet channel and two gas outlet channels; the dust remover is connected with the air compressor through a pipeline; the cold drying machine is connected with the nitrogen making machine through a pipeline; the air compressor and the nitrogen making machine are connected with the air inlet end of the supercharger through a three-way valve, and a pressure stabilizing tank and a manual ball valve are sequentially arranged on a pipeline between the three-way valve and the supercharger along the conveying direction of gas; the air outlet end of the supercharger is connected with one end of the first electric valve through a welding flange, the other end of the first electric valve is connected with the air inlet channel of the three-channel electric valve, a flow meter, a one-way valve, a temperature sensor and a pressure sensor are sequentially arranged between the first electric valve and the three-channel electric valve, one air outlet channel of the three-channel electric valve is in static pressure contact with a well head flange of an injection and production well of the central injection and production well through a pipeline, the other air outlet channel forms an injection and production loop with six peripheral injection and production wells through a pipeline, an electric valve II, an electric valve III, an electric valve IV, an electric valve V, an electric valve VI and an electric valve VII are sequentially arranged on the injection and production loop in the anticlockwise direction, and the electric valve II, the electric valve III, the electric valve IV, the electric valve V, the electric valve VI and the electric valve VII respectively control the six surrounding injection and production wells to be opened and closed correspondingly;
the heating system comprises an oil pipe and an underground heater, the number of the underground heater is consistent with that of injection and production wells in the well network system, the underground heater and the injection and production wells are in one-to-one correspondence, the lower portion of the oil pipe is in threaded connection with an upper suspension device of the underground heater, a sealing wire cabin of the underground heater and a copper-clad cable which is inserted into the well along with the well are welded and sealed after wiring is completed, then the copper-clad cable is connected to a well head of the injection and production well along with the oil pipe through a hoop in a static pressure contact mode, and the copper-clad cable is in sealed connection with the well head of the injection and production well.
Furthermore, all injection and production wells in the well pattern system are all through-diameter vertical wells with the diameter of 311mm, a drill bit with the diameter of 400mm is used for drilling a hole to the boundary of a superficial soil layer and a rock stratum, a drill bit with the diameter of 311mm is used for drilling a second well to an oil shale stratum of a target interval, and the well spacing between the injection and production wells in the well pattern system is 50-100 m.
Further, the supercharger is a four-stage piston compressor.
The oil shale in-situ mining reaction area control process method is characterized in that shale oil gas mining is carried out on the basis of the oil shale in-situ mining reaction area control system, and the method specifically comprises the following steps:
selecting an oil shale in-situ mining block, drilling seven injection-production wells in the selected oil shale in-situ mining block to form a regular hexagon seven-point well network, and putting a logging instrument and a logging instrument into a central injection-production well to determine a target interval of an oil shale layer;
step two, sequentially carrying out multiple time-sharing fracturing construction in the injection and production well to complete the transformation of an oil shale layer reservoir, carrying out an inter-well connectivity test after the fracturing fluid is drained back, and entering the next step after the test is qualified;
thirdly, after the underground heater and the copper-clad cable are connected on the ground and installed in a sealing mode, the copper-clad cable penetrates through the well head of the injection and production well, the tower crane enters the field to place the underground heater into the injection and production well after the oil pipe is connected with the underground heater, the underground heater is completed, and the well head of the injection and production well is installed;
step four, drying the preheated oil shale layer: starting an underground heater in the central injection and production well, setting the heating temperature of the underground heater to 300 ℃, taking the central injection and production well as a heat injection well and six peripheral injection and production wells as production wells, and adjusting the gas injection pressure by 6-12 Mpa and the gas injection pressure by 200Nm3/h～300Nm3The injection flow rate can be adjusted to inject 300 ℃ high-temperature nitrogen into the oil shale layer target interval, the 300 ℃ high-temperature nitrogen is used as a heat carrier nitrogen medium to form forced convection heat transfer through a fracturing seepage channel, so that the temperature is reduced from the center to the periphery in a gradient manner from high to low in the direction from the center to the periphery of the injection and production well group, the pressure of the periphery injection and production well group is maintained to be 0.3-0.8 Mpa, and the heating period is 7 days;
in a preferred embodiment of the present invention, the gas injection pressure is adjusted to 6MPa to 12MPa, and 200Nm is used3/h～300Nm3The process of injecting 300 ℃ high-temperature nitrogen into the target interval of the oil shale layer by adjusting the gas injection flow is as follows: the gas injection temperature is kept constant all the time, and in the initial stage of gas injection, the gas injection pressure and the gas injection flow are respectively selected from a gas injection pressure interval of 6-12 Mpa and a gas injection flow interval of 200Nm3/h～300Nm3The lowest value of the interval of/h, the formation thermal expansion and thermal stress increase along with the formation temperature rise, the gas injection pressure is 3 Mpa/time, and the gas injection flow is 50 Nm/time3The gradient/h increases;
step five, a single-well huff and puff high-temperature oil shale layer heating stage: closing six peripheral injection and production wells, setting the heating temperature range of the underground heater in the central injection and production well to be 450-520 ℃, and setting the heating temperature range to be 6-20 Mpa injection pressure range and 200Nm3/h～300Nm3The gas injection with the technological parameters of adjustable gas injection flow is carried out, the single well is taken in and out in the central injection and production well, the oil shale layer is heated, the heating period is 24 hours, so that the oil shale layer between the central injection and production well and the surrounding injection and production well group heat sequentially forms an in-situ conversion residual carbon zone, an in-situ conversion cracking zone and an in-situ conversion cracking zoneA conversion oxidation zone, an in-situ conversion preheating zone and an in-situ conversion drying zone;
as a preferred scheme of the invention, in the gas injection process, in the initial stage of gas injection, the minimum value of each interval is selected for the gas injection temperature, the gas injection pressure and the gas injection flow, the gas injection temperature is increased by 20 ℃/time, the gas injection pressure is increased by 5 Mpa/time, and the gas injection flow is increased by 50 (Nm)3Step-by-step gradient increasing adjustment is performed for each step;
sixthly, back gas injection self-heating oil shale layer heating stage: closing an underground heater in a central injection-production well, opening the underground heater in six peripheral injection-production wells, adjusting a three-channel electric valve to be communicated with an injection-production loop formed by the six peripheral injection-production wells, opening an electric valve II, an electric valve III, an electric valve IV, an electric valve V, an electric valve VI and an electric valve VII, taking the central injection-production well as a production well, taking the six peripheral injection-production wells as injection wells, setting the heating temperature interval of the underground heater in the six peripheral injection-production wells to be 200-250 ℃, the gas injection pressure to be 10-15 MPa and the gas injection flow interval to be 25Nm3/h～50Nm3Conveying preheated air to the central injection and production well through the internal hole fracture seepage channel of the oil shale layer, enabling oxygen in the preheated air to perform self-heating oxidation reaction with kerogen and fixed carbon in the oil shale in the in-situ conversion cracking area and the in-situ conversion oxidation area to release heat, separating out oil and gas products, reversely passing through the in-situ conversion carbon residue area, extracting the oil and gas products to the ground through the central injection and production well, and enabling the extraction period to be 3-4 days;
as a preferred scheme of the invention, in the gas injection process, the minimum value of each interval is selected according to the gas injection temperature, the gas injection pressure and the gas injection flow at the initial injection stage, the gas migration condition from the central injection-production well to the peripheral injection-production wells is smooth, the temperature is 20 ℃/times, the gas injection pressure is 2 Mpa/time, and the gas injection flow is 10 (Nm)3Step-by-step incremental adjustment per time;
seventhly, a normal-temperature back gas injection self-heating reaction stage: the underground heater in the injection and production well around the six ports is closed, the gas injection pressure can be adjusted at normal temperature and 10-15 Mpa, and the gas injection pressure is 25Nm3/h～50Nm3Perh process parameter of adjustable gas injection flow rate to continue injecting airGas, so that the in-situ conversion carbon residue area, the in-situ conversion cracking area, the in-situ conversion oxidation area, the in-situ conversion preheating area and the in-situ conversion drying area gradually evolve from the central injection-production well to the direction of the peripheral injection-production well group, and the production period is 3-4 days;
as a preferred scheme of the invention, in the gas injection process, the minimum value of each interval is selected from the gas injection pressure and the gas injection flow at the initial injection stage, the gas injection pressure is 2 Mpa/time according to the smooth gas migration condition from the central injection-production well to the peripheral injection-production wells, and the gas injection flow is 10 Nm/time3And/h is adjusted in a step-by-step increasing mode.
Step eight, a high-pressure shale oil-gas displacement stage: the gas injection pressure of the surrounding injection and production wells can be adjusted at normal temperature and 10-20 Mpa, and the gas injection pressure is 50Nm3/h～100Nm3The technological parameters of the injection flow can be adjusted to continuously inject air, the residual oil and gas products in the target interval of the oil shale layer are displaced to a central injection and production well and extracted to the ground surface for separation, the gas injection period is 12 hours, and the exploitation of the target interval of the underground oil shale layer is completed;
as a preferred scheme of the invention, the minimum value of each interval is selected from the gas injection pressure and the gas injection flow at the initial injection stage, the gas injection pressure is 10 Mpa/time and the gas injection flow is 50 (Nm) according to the oil and gas displacement condition from the central injection-production well to the peripheral injection-production wells3Step-by-step ascending adjustment is carried out per time;
and step nine, after construction is finished, opening all injection and production well annuluses, evacuating gas in all the injection and production wells, opening injection and production well heads in all the injection and production wells, completing recovery work of oil pipes, underground heaters and copper cables, cementing and sealing the central injection and production well, and performing shale oil and gas exploitation of the next oil shale in-situ exploitation block by taking the peripheral injection and production wells as the well arrangement of the adjacent blocks.
Further, when the surrounding injection and production well groups are used as injection wells or production wells in the shale oil and gas in-situ exploitation reaction zone control process method, the pressure of more than or equal to 0.3Mpa is maintained in the wells, so that an isobaric gas drive closed boundary is formed, and oil and gas are prevented from escaping.
Through the design scheme, the invention can bring the following beneficial effects: the invention provides a control system and a process method for an oil shale in-situ mining reaction zone, wherein seven injection and production wells are drilled in the oil shale in-situ mining zone to form a well pattern system, and an oil pipe and an underground heater are put into the well through ground tower crane equipment to realize underground heating, so that the ground heat injection heat loss along the way is reduced, and the heat injection efficiency is improved; the process is divided into five stages, in the operation process of the cracking reaction process, the reverse gas injection process ensures that the pyrolysis direction of the oil shale is orderly carried out from a central injection well to the peripheral injection well, the process parameters of temperature, pressure and flow in the construction process are adjustable, the process parameters are adjusted to control the pyrolysis reaction rate of the oil shale under the well at any time, so that the reaction is continuously carried out towards the direction of increasing entropy, the reverse gas injection exploitation process can ensure that the cracked shale oil gas is transported to the central injection well through an oil shale layer fracturing seepage channel and a hole crack channel of an in-situ conversion residual carbon zone and is extracted to the earth surface, the problem that the cracking produced shale oil and asphalt products enter a low-temperature zone from the high-temperature zone and the viscosity of the shale oil gas is increased to cause the blockage of the fracturing seepage channel to form the result that the oil gas cannot be transported is solved, the shale oil gas in-situ exploitation under the long-well spacing well arrangement scheme condition can be met, and the reverse gas injection process principle is adopted, the construction period is obviously shortened, underground accidents are few, the construction operability is strong, the heat injection effect is good, the energy utilization rate is high, and the construction cost is obviously reduced.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention to the right, and in which:
FIG. 1 is a general layout of an oil shale in situ production reaction zone control system;
FIG. 2 is a schematic diagram of a well pattern layout of an oil shale in situ production reaction zone control system;
FIG. 3 is a sectional view of an in situ pyrolysis zone of an in situ mining reaction zone control process for oil shale;
FIG. 4 is a plan view of an in-situ pyrolysis zone of an in-situ oil shale mining reaction zone control process;
FIG. 5 is a schematic diagram of a back gas injection in-situ cracking principle of a process control method for an oil shale in-situ mining reaction zone;
FIG. 6 is a schematic diagram of surface equipment of an oil shale in situ production reaction zone control system.
The respective symbols in the figure are as follows: 1-an upper cladding layer; 2-an oil shale layer; 3-an underlying layer; 4-injection and production well I; 5-injection and production well II; 6-injection and production well III; 7-injection and production well four; 8-injection and production well five; 9-injection and production well six; 10-injection and production well seven; 11-well head of injection and production well; 12-an oil pipe; 13-a downhole heater; 14-isobaric gas drive closed boundary; 15-in-situ conversion of carbon residue region; 16-an in situ conversion cleavage zone; 17-an in-situ conversion oxidation zone; 18-in situ reforming preheating zone; 19-an in situ conversion drying zone; 20-fracturing the seepage channels; 21-a proppant; 22-flow trace; 23-a dust remover; 24-a pipeline; 25-an air compressor; 26-a cold dryer; 27-nitrogen making machine; 28-three-way valve; 29-a surge tank; 30-a manual ball valve; 31-a supercharger; 32-an electrically operated valve I; 33-a flow meter; 34-a one-way valve; 35-a temperature sensor; 36-a pressure sensor; 37-three-way electric valve; 38-electrically operated valve two; 39-electrically operated valve III; 40-electrically operated valve four; 41-electrically operated valve five; 42-electrically operated valve six; 43-electric valve seven.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.
As shown in fig. 1, fig. 2, fig. 3, fig. 4, fig. 5, and fig. 6, an oil shale in situ production reaction zone control system comprises a well pattern system, a heating system, and a surface gas injection system, wherein:
the well pattern system is deployed in an oil shale exploitation block, as shown in fig. 1 and 2, the well pattern system is composed of seven injection-production wells, the injection-production well arrangement scheme adopts a seven-well regular hexagon well arrangement mode commonly used in the field of oil exploitation, for convenience of description, in the embodiment, a central injection-production well is called an injection-production well I4, and six peripheral injection-production wells are respectively called an injection-production well II 5, an injection-production well III 6, an injection-production well IV 7, an injection-production well V8, an injection-production well VI 9 and an injection-production well VII 10. And the first 4 injection and production well is used as an injection well to inject high-temperature nitrogen at 200-520 ℃ into the well in the early stage, and is used as a production well to lift oil and gas products to the surface in the later stage. In the initial stage of the injection and production of the peripheral injection and production wells, the pressure in the wells is maintained between 0.3Mpa and 0.8Mpa, and an isobaric gas drive closed boundary 14 is formed, so that the underground water is prevented from being invaded in the construction process. The interval between injection and production wells in the well arrangement scheme is 50-100 m, the injection and production wells are all 311mm drift diameter vertical wells, a 400mm diameter drill bit for drilling a well is used for drilling a hole to a boundary between a superficial soil layer and a rock stratum, a 311mm diameter drill bit for drilling a second well is used for drilling an oil shale layer 2 of a target interval, the injection and production wells can be switched into an injection and production mode at any time according to process requirements, CA-50 high temperature resistant aluminate cement is adopted for cementing all the injection and production wells, and all the injection and production wells are provided with underground heaters 13, so that bottom hole heating can be realized. Gas is injected into the central tubular column of the oil pipe 12 in the well, and the annular space is drained back. Oil shale layer 2 is located between overburden 1 and underburden 3 and oil shale layer 2 is located 467 m-488 m underground.
As shown in fig. 6, the ground gas injection system includes a dust collector 23, an air compressor 25, a freeze dryer 26, a nitrogen generator 27, a three-way valve 28, a surge tank 29, a manual ball valve 30, a supercharger 31, a first electric valve 32, a flow meter 33, a check valve 34, a temperature sensor 35, a pressure sensor 36, a three-way electric valve 37, a second electric valve 38, a third electric valve 39, a fourth electric valve 40, a fifth electric valve 41, a sixth electric valve 42 and a seventh electric valve 43, wherein the three-way electric valve 37 has one gas inlet channel and two gas outlet channels; the dust remover 23 is connected with an air compressor 25 through a pipeline 24; the cold dryer 26 is connected with the nitrogen making machine 27 through a pipeline 24; the air compressor 25 and the nitrogen generator 27 are connected with the air inlet end of the supercharger 31 through a three-way valve 28, and a pressure stabilizing tank 29 and a manual ball valve 30 are sequentially arranged on a pipeline 24 between the three-way valve 28 and the supercharger 31 along the conveying direction of the gas; the air outlet end of the supercharger 31 is connected with one end of a first electric valve 32 through a welding flange, the other end of the first electric valve 32 is connected with an air inlet channel of a three-channel electric valve 37, a flow meter 33, a one-way valve 34, a temperature sensor 35 and a pressure sensor 36 are sequentially arranged between the first electric valve 32 and the three-channel electric valve 37, one air outlet channel of the three-channel electric valve 37 is in static pressure contact with a flange of a well head 11 of an injection and production well of a central injection and production well through a pipeline, the other air outlet channel forms an injection and production loop with six surrounding injection and production wells through pipelines, and a second electric valve 38, a third electric valve 39, a fourth electric valve 40, a fifth electric valve 41, a sixth electric valve 42, a seventh electric valve 43, a second electric valve 38, a third electric valve 39, a fourth electric valve 40 and a fifth electric valve 41 are sequentially arranged on the injection and production loop in a counterclockwise direction, Six electric valves 42 and seven electric valves 43 correspond to six peripheral injection and production wells respectively; the dust separator 23 is preferably a cyclone; the air compressor 25 is preferably a screw compressor, the supercharger 31 is a four-stage piston compressor, the supercharger 31 and the air compressor 25 or the cold dryer 26 form five-stage compression during operation, the air compressor 25 or the cold dryer 26 is one-stage, and the supercharger 31 compresses four cylinders step by step. In the process of the nitrogen making machine 27, the purity of the injected nitrogen is not lower than 99.7%.
The heating system comprises an oil pipe 12 and downhole heaters 13, the number of the downhole heaters 13 is consistent with that of injection and production wells in the well network system, the downhole heaters are in one-to-one correspondence, the lower portion of the oil pipe 12 is in threaded connection with a suspension device at the upper portion of the downhole heaters 13, a sealing wire cabin of the downhole heaters 13 is welded and sealed after the wiring of copper cables entering the well is completed, then the copper cables are connected to an injection and production well head 11 along with the oil pipe 12 through clamp static pressure contact, and the copper cables are in sealing connection with the injection and production well head 11. The injection and production well head 11 of the present invention is a well head commonly used in the field of oil production, and the structure thereof will not be described in detail herein.
Further, the heating temperature range of the underground heater 13 is 0-550 ℃, the designed service life is 3000h, and the pressure resistance is 30 Mpa.
Further, the construction gas injection pressure of the supercharger 31 is 0-30 Mpa, and the gas injection flow is 0-600 Nm3/h；
The technological parameters of the control system comprise gas injection flow, gas injection pressure and gas injection temperature, wherein the gas injection flow range is 0-600 Nm3H, gas injection temperatureThe temperature is 0-550 ℃, and the gas injection pressure is 0-30 Mpa.
Further, during the in-situ exploitation and heat injection period of the oil shale layer 2, kerogen is continuously cracked and separated out from the center to the periphery of the oil shale layer 2 of a target interval between the injection and extraction wells due to the temperature rise of the stratum to respectively form an in-situ conversion carbon residue area 15, an in-situ conversion cracking area 16, an in-situ conversion oxidation area 17, an in-situ conversion preheating area 18 and an in-situ conversion drying area 19.
Fig. 5 is a schematic diagram of a back gas injection in-situ cracking principle of the oil shale in-situ exploitation reaction zone control process method, as shown in fig. 5, the schematic diagram corresponds to a drying preheating stage, a high-temperature heating huff and puff stage, a back gas injection self-heating gas injection stage and a normal temperature back gas injection self-heating exploitation stage from top to bottom, and represents evolution directions of different in-situ conversion zones from a central injection and exploitation well to surrounding injection and exploitation well groups from left to right.
Fig. 3 and 4 are a sectional view and a sectional top view of an in-situ cracking zone of the oil shale in-situ mining reaction zone control process, which are respectively expressed by only selecting a schematic diagram of local well location distribution for convenient visual representation of graphs. In the figure, proppant 21 is located in fracture-seepage channel 20, and flow trace 22 represents the gas migration direction, which is not described in detail herein in the prior art.
The working principle and the process of the invention are as follows: starting the cold drying machine 26 to supply air for the nitrogen making machine 27, adjusting the three-way valve 28 to a passage of the nitrogen making machine 27, enabling high-purity nitrogen (the purity of the nitrogen is not lower than 99.7 percent) to enter a pressure stabilizing tank 29 to form stable air flow supply, opening the manual ball valve 30, stabilizing the pressure of the high-purity nitrogen through the pressure stabilizing tank 29 to stabilize an air supply source for the supercharger 31, compressing the supercharger 31 through a four-stage piston to obtain high-pressure gas with the pressure of 8 Mpa-35 Mpa, opening the first electric valve 32, enabling the gas to sequentially pass through the flowmeter 33, the one-way valve 34, the temperature sensor 35, the pressure sensor 36 and the three-channel electric valve 37 through the pipeline 24, and selecting the three-channel electric valve 37 to a 4-pipeline passage of the injection and production wellThe first injection well 4 is used as an injection heat well, the second injection well 5, the third injection well 6, the fourth injection well 7, the fifth injection well 8, the sixth injection well 9 and the seventh injection well 10 are used as extraction wells, so that the oil shale layer 2 realizes forced convection heat exchange to heat the target layer section, the injection pressure can be adjusted by 6 Mpa-12 Mpa, and 200Nm (Nm) is used for heating the target layer section3/h～300Nm3The injection flow rate can be adjusted, high-temperature nitrogen is injected into the six injection and production wells around from the first injection and production well 4 at the injection temperature of 300 ℃, the gas is injected for 7 days, the drying and preheating of the oil shale layer 2 are completed, and the oil shale layer 2 forms an in-situ conversion zone drying layer after the drying and preheating are completed; at the moment, closing the second injection and production well 5, the third injection and production well 6, the fourth injection and production well 7, the fifth injection and production well 8, the sixth injection and production well 9 and the seventh injection and production well 10, carrying out huff and puff operation on the first injection and production well 4, increasing the gas injection temperature, setting the heating temperature interval of the downhole heater 13 to be 450-520 ℃ through a ground PID central control system, and injecting gas at the pressure of 6-20 Mpa and the gas injection pressure of 200Nm3/h～300Nm3The process parameter of the gas injection flow can be adjusted, the gas is injected for 24 hours, the gas is sequentially converted into an in-situ conversion carbon residue area 15, an in-situ conversion cracking area 16, an in-situ conversion oxidation area 17, an in-situ conversion preheating area 18 and an in-situ conversion drying area 19 from the first injection well 4 to the surrounding injection well group direction, and the downhole heater 13 in the first injection well 4 is closed; opening the dust remover 23, starting the air compressor 25, adjusting the three-way valve 28 to the passage of the air compressor 25, selecting the three-way electric valve 37 to the surrounding injection and production well group pipeline passage, opening the electric valve two 38, the electric valve three 39, the electric valve four 40, the electric valve five 41, the electric valve six 42 and the electric valve seven 43 to perform reverse gas injection and self-heating to heat the oil shale layer 2, as shown in figure 5, taking the injection and production well one 4 as an extraction well, taking the injection and production well two 5, the injection and production well three 6, the injection and production well four 7, the injection and production well five 8, the injection and production well six 9 and the injection and production well seven 10 as injection wells, opening the downhole heaters 13 in the surrounding injection and production well group, and adjusting the gas injection temperature to be 200-250 ℃, the gas injection pressure to be 10-15 Mpa and the gas injection pressure to be 25Nm3/h～50Nm3Injecting preheated air from the surrounding injection and production well groups to the injection and production well I4 by adjustable gas injection flow to form a reverse gas injection process, wherein oxygen in the preheated air stably and continuously passes through an in-situ conversion drying zone 19, an in-situ conversion preheating zone 18, an in-situ conversion oxidation zone 17, a fracturing seepage channel 20 in sequence,The in-situ conversion cracking zone 16 and kerogen and organic carbon in the oil shale layer 2 of the in-situ conversion oxidation zone 17 and the in-situ conversion cracking zone 16 are subjected to self-heating chemical reaction, oil gas products generated by the reaction are enriched to the injection and production well I4 through the in-situ conversion residual carbon zone 15 and are lifted to the ground surface, and the production period is 3-4 days; closing the underground heaters 13 in the surrounding injection and production well groups, and injecting gas at normal temperature and 10-15 Mpa with adjustable gas injection pressure and 25Nm per well3/h～50Nm3The gas injection is continued by adjusting the technological parameters of the gas injection flow, the in-situ conversion carbon residue zone 15, the in-situ conversion cracking zone 16, the in-situ conversion oxidation zone 17, the in-situ conversion preheating zone 18 and the in-situ conversion drying zone 19 are gradually pushed from the injection and production well I4 to the surrounding injection and production well group, and the mining period is 3-4 days; after the 2-mesh interval of the oil shale layer is completely exploited, the surrounding injection and production well groups are injected at normal temperature and the gas injection pressure of 10 Mpa-20 Mpa and the adjustable injection flow of 50Nm3/h～100Nm3And continuously injecting gas according to the process parameters of the/h, and displacing the residual oil and gas products in the target interval of the oil shale layer 2 to the injection and production well I4, extracting to the surface of the earth and separating, wherein the gas injection period is 12 h.
The process method for controlling the oil shale in-situ mining reaction area is based on an oil shale in-situ mining reaction area control system for mining, and specifically comprises the following steps, wherein the following steps are sequentially carried out:
selecting an oil shale in-situ mining block, drilling seven injection-production wells in the selected oil shale in-situ mining block to form a well pattern, and putting a logging instrument and a logging instrument into a first 4 wells of the injection-production wells to finish the accurate selection of a target interval of an oil shale layer 2;
step two, performing separated well multiple fracturing construction in an injection and production well of a well pattern system to complete reservoir transformation of the oil shale layer 2, performing inter-well connectivity test after fracturing fluid is drained back, measuring and calculating inter-well connectivity conditions, and entering the next step after the test is qualified;
and step three, completing ground wiring and sealing installation work of the underground heater 13 and a copper-clad cable, enabling the copper-clad cable to penetrate through the injection and production well head 11, after the oil pipe 12 is connected with the underground heater 13, enabling the underground heater 13 to be placed into the injection and production well by a tower crane in the field, enabling the drill rod elevator to hang the oil pipe 12 to be sequentially in threaded connection, completing the underground operation of the underground heater 13, and installing the injection and production well head 11.
Step four, drying the preheated oil shale layer 2 stage: starting the downhole heater 13 in the injection and production well I4, setting the heating temperature interval of the downhole heater 13 to 300 ℃, taking the central injection and production well as the heat injection well and the six peripheral injection and production wells as the production wells, and adjusting the gas injection pressure by 6-12 Mpa and the gas injection pressure by 200Nm3/h～300Nm3The gas injection flow can be adjusted to inject high-temperature nitrogen into the 2-purpose layer section of the oil shale layer, the gas injection temperature is unchanged in the gas injection process, the lowest value of the interval is selected between the gas injection pressure and the gas injection flow in the initial gas injection stage, the formation thermal expansion and the thermal stress are increased along with the formation temperature rise, the gas injection pressure is 3 Mpa/time, and the gas injection pressure is 50Nm3The gradient/time is increased so that gas media can smoothly pass through, high-temperature nitrogen is used as a heat carrier medium to form forced convection heat exchange through gaps inside propping agents 21 in the fracturing seepage channel 20, 300 ℃ high-temperature nitrogen is injected from the injection and production well I4 to the peripheral injection and production well group, namely the injection and production well II 5, the injection and production well III 6, the injection and production well IV 7, the injection and production well V8, the injection and production well VI 9 and the injection and production well VII 10, the temperature is gradually reduced from the central injection and production well (namely the injection and production well I4) to the peripheral injection and production well group, the pressure of the peripheral injection and production well group is maintained to be 0.3-0.8 Mpa, and the heating period is 7 days;
step five, single-well huff and puff high-temperature heating of the oil shale layer 2 stage: closing the injection and production well II 5, the injection and production well III 6, the injection and production well IV 7, the injection and production well V8, the injection and production well VI 9 and the injection and production well VII 10, setting the heating temperature range of the underground heater 13 in the injection and production well I4 to be 450-520 ℃, setting the pressure range of the injection gas to be 6-20 Mpa, and setting the pressure to be 200Nm3/h～300Nm3The process parameters of the gas injection flow can be adjusted to carry out single well throughput in the injection-production well I4, the minimum value of each interval is selected from the gas injection temperature, the gas injection pressure and the gas injection flow, the gas injection temperature is increased by 20 ℃/times, the gas injection pressure is increased by 5 Mpa/time, and the gas injection flow is 50 (Nm)3Step-by-step gradient increasing and adjusting for the times of/h), heating the oil shale layer 2 at high temperature, wherein the heating period is 24 h;
step six, back gas injection self-heating oil shale layer 2 stage: after heating the oil shale layer 2 at a high temperature,sequentially forming an in-situ conversion residual carbon zone 15, an in-situ conversion cracking zone 16, an in-situ conversion oxidation zone 17, an in-situ conversion preheating zone 18 and an in-situ conversion drying zone 19 from the first injection and production well 4 to the hot oil shale layer 2 of the surrounding injection and production well group, closing the underground heater 13 in the central injection and production well, opening the underground heaters 13 in the six surrounding injection and production wells, adjusting a three-channel electric valve 37 to be communicated with the six surrounding injection and production wells, opening an electric valve two 38, an electric valve three 39, an electric valve four 40, an electric valve five 41, an electric valve six 42 and an electric valve seven 43, taking the central injection and production well as an extraction well, taking the six surrounding injection and production wells as injection wells, setting the heating temperature interval of the underground heaters 13 in the second injection and production wells 5 to the seventh injection and production well 10 to 250 ℃, the gas injection pressure to be 10 to 15MPa, and the gas injection flow interval to be 25Nm3/h～50Nm3H, selecting the minimum value of each interval at the initial stage of injection process parameters, and according to the smooth gas migration condition from the central injection-production well to the peripheral injection-production wells, controlling the temperature at 20 ℃/time, controlling the pressure at 2 Mpa/time, and controlling the gas injection flow at 10 (Nm)3Step-by-step incremental adjustment is carried out step by step, wherein the gas injection temperature, the gas injection pressure and the gas injection flow can not exceed 200-250 ℃, the gas injection temperature is 10-15 MPa, and the gas injection pressure is 25Nm3/h～50Nm3Injecting preheated air into an injection and production well I4 through an inner hole fracture seepage channel of an oil shale layer 2 by adjustable injection technological parameters, wherein a self-heating reaction is an oxidation exothermic reaction, carbon in residues formed after kerogen cracking is used as a reaction heat release source, the reaction is continuously carried out, oxygen in the preheated air and high-temperature melting-out kerogen and fixed carbon in the oil shale layer 2 in an in-situ conversion cracking area 16 and an in-situ conversion oxidation area 17 generate the self-heating cracking reaction to release heat, oil and gas products are separated out and reversely pass through a highly-broken in-situ conversion residual carbon area 15, the oil and gas products are extracted to the ground through the injection and production well I4, and the extraction period is 3-4 days;
seventhly, a normal-temperature back gas injection self-heating reaction stage: closing the downhole heaters 13 in the second injection and production well 5, the third injection and production well 6, the fourth injection and production well 7, the fifth injection and production well 8, the sixth injection and production well 9 and the seventh injection and production well 10, and adjusting the gas injection pressure and the 25Nm and the 15 Nm at normal temperature by 10-15 Mpa3/h～50Nm3The gas injection is continued according to the technological parameters of the adjustable gas injection flow, the gas migration from the central injection-production well to the peripheral injection-production wells is smooth, the pressure is 2 Mpa/time, and the gas injection flow is 10 (Nm)3Step-by-step incremental adjustment in per hour, it should be noted that the gas injection pressure and flow rate cannot exceed 10 MPa-15 MPa, and the gas injection pressure can be adjusted, and the gas injection flow rate is 25Nm3/h～50Nm3The upper limit value of technological parameters of the gas injection flow can be adjusted, the in-situ conversion carbon residue zone 15, the in-situ conversion cracking zone 16, the in-situ conversion oxidation zone 17, the in-situ conversion preheating zone 18 and the in-situ conversion drying zone 19 are gradually pushed from the injection-production well I4 to the surrounding injection-production well group, and the production period is 3-4 days;
step eight, a high-pressure shale oil-gas displacement stage: the surrounding injection and production well group can adjust the gas injection pressure and 50Nm at normal temperature and 10-20 Mpa3/h～100Nm3The injection flow can be adjusted by the method of regulating the process parameters of the injection flow to continuously inject gas, the gas injection pressure is 10 Mpa/time according to the oil gas displacement condition from the central injection-production well to the peripheral injection-production wells, and the gas injection flow is 50 (Nm)3Step-by-step ascending adjustment is performed step by step, and it needs to be noted that the gas injection pressure and the gas injection flow can not exceed 0Mpa to 20Mpa, the gas injection pressure can be adjusted, and the gas injection flow can not exceed 50Nm3/h～100Nm3The upper limit value of the technological parameter of the injection flow can be adjusted, the residual oil gas products in the target interval of the oil shale layer 2 are displaced to the injection and production well I4 and extracted to the ground surface for separation, the gas injection period is 12 hours, and the exploitation of the target interval of the underground oil shale layer 2 is completed;
and step nine, after construction is finished, opening all injection and production well annuluses, evacuating gas in all the injection and production wells, opening the injection and production well heads 11 in all the injection and production wells, completing the recovery work of the oil pipes 12, the underground heaters 13 and the copper-clad cables, sealing the central injection and production well by cement, and performing shale oil and gas exploitation of the next oil shale in-situ exploitation block by taking the peripheral injection and production wells as the well arrangement of the adjacent blocks.
According to the oil shale in-situ mining reaction zone control process method, during the gas injection process, the stratum is further dried and preheated in the first stage; in the second stage, high-temperature single-well huff and puff is carried out, oil shale at the near well end of the central injection and production well is quickly cracked, the porosity and the permeability are quickly increased, oil and gas products at the near well end are enriched in the central injection and production well through a huff and puff method, and the temperature at the near well end is high; in the third stage, the oil shale layer 2 is heated by self-heating of reverse gas injection, and at the moment, reverse gas injection is carried out from the surrounding injection and production well groups to the central injection and production well, so that the problem of underground production blockage caused by blockage of a seepage channel due to rapid cooling of large heat loss caused by long-distance migration of shale oil and gas can be prevented; the fourth stage, back injecting air at normal temperature to make the cracking reaction slowly proceed toward the direction of the surrounding injection and production well group; and in the fifth stage, shale oil gas is displaced at high pressure, the cracking reaction is continuously carried out towards the direction of the surrounding injection and production well group until the reaction is complete, and according to the underground condition, the surrounding injection and production wells adopt adjustable flow injection parameters to carry out high-pressure displacement, so that oil gas products in the completely-reacted in-situ conversion carbon residue region 15 are displaced to the central injection and production well, and the whole construction of the process is completed.
The control process parameters comprise temperature, pressure and flow, and the process parameters can be adjusted to control the rate of the self-heating reaction of the target layer section of the oil shale layer 2 and ensure that the reaction is carried out towards the direction of entropy increase.
No matter the peripheral injection and production well group provided by the invention is used as an injection well or a production well, the pressure in the well is not less than 0.3Mpa, so that an isobaric gas drive closed boundary 14 is formed to prevent underground water from further entering an in-situ conversion reaction zone and simultaneously prevent oil gas from escaping.
According to the back-injection gas self-heating reaction process, the shale oil asphaltene viscosity increase caused by overhigh heat loss in the migration process of a fused high-temperature oil gas product is avoided in the reaction process, so that a fracturing seepage channel and an oil shale in-situ pore seepage channel are blocked, a carrier gas medium is not influenced by the rock stratum thermal expansion effect and shale oil and asphalt products in the back-injection gas process, the gas injection is uniform, the reaction is continuously and stably carried out, the heat injection efficiency is high, the exploitation period is short, the underground accidents are few, and the back-injection gas self-heating reaction process is suitable for the underground in-situ exploitation of shale oil gas with a long well spacing.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that various changes, modifications and substitutions can be made without departing from the spirit and scope of the invention as defined by the appended claims. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. Oil shale in situ mining reaction zone control system, its characterized in that includes: a well pattern system, a heating system and a ground gas injection system;
the well pattern system is a regular hexagon seven-point well pattern formed by seven injection and production wells, the well pattern unit consists of six peripheral injection and production wells positioned at six vertexes of the regular hexagon and one central injection and production well positioned at the center of the regular hexagon, the six peripheral injection and production wells form a peripheral injection and production well group, and all the injection and production wells in the well pattern unit are provided with injection and production well heads (11);
the ground gas injection system comprises a dust remover (23), an air compressor (25), a cold dryer (26), a nitrogen making machine (27), a three-way valve (28), a pressure stabilizing tank (29), a manual ball valve (30), a supercharger (31), an electric valve I (32), a flow meter (33), a one-way valve (34), a temperature sensor (35), a pressure sensor (36), a three-way electric valve (37), an electric valve II (38), an electric valve III (39), an electric valve IV (40), an electric valve V (41), an electric valve VI (42) and an electric valve VII (43), wherein the three-way electric valve (37) is provided with a gas inlet channel and two gas outlet channels; the dust remover (23) is connected with an air compressor (25) through a pipeline (24); the cold dryer (26) is connected with the nitrogen making machine (27) through a pipeline (24); the air compressor (25) and the nitrogen making machine (27) are connected with the air inlet end of the supercharger (31) through a three-way valve (28), and a pressure stabilizing tank (29) and a manual ball valve (30) are sequentially arranged on a pipeline (24) between the three-way valve (28) and the supercharger (31) along the conveying direction of gas; the air outlet end of the supercharger (31) is connected with one end of a first electric valve (32) through a welding flange, the other end of the first electric valve (32) is connected with an air inlet channel of a three-channel electric valve (37), a flow meter (33), a one-way valve (34), a temperature sensor (35) and a pressure sensor (36) are sequentially arranged between the first electric valve (32) and the three-channel electric valve (37), one air outlet channel of the three-channel electric valve (37) is in static pressure contact with a flange of an injection and production well head (11) of a central injection and production well through a pipeline, the other air outlet channel forms an injection and production loop with six peripheral injection and production wells through a pipeline, and a second electric valve (38), a third electric valve (39), a fourth electric valve (40), a fifth electric valve (41), a sixth electric valve (42) and a seventh electric valve (43) are sequentially arranged on the injection and production loop in a counterclockwise direction, the electric valve II (38), the electric valve III (39), the electric valve IV (40), the electric valve V (41), the electric valve VI (42) and the electric valve VII (43) respectively correspond to six peripheral injection and production wells;
the heating system comprises an oil pipe (12) and underground heaters (13), the number of the underground heaters (13) is consistent with that of injection and production wells in a well network system and is in one-to-one correspondence, the lower portion of the oil pipe (12) is in threaded connection with an upper suspension device of the underground heaters (13), a sealing wiring bin of the underground heaters (13) is welded and sealed after wiring of copper cables entering along with the underground wells is completed, then the copper cables are connected to injection and production well heads (11) along with the oil pipe (12) through clamp static pressure contact, and the copper cables are in sealing connection with the injection and production well heads (11).
2. The oil shale in-situ mining reaction zone control system of claim 1, wherein: all injection and production wells in the well pattern system are all through-diameter vertical wells with the diameter of 311mm, a drill bit with the diameter of 400mm is used for drilling a well to reach the junction of a superficial soil layer and a rock stratum, a drill bit with the diameter of 311mm is used for drilling a well to reach an oil shale stratum (2) of a target interval, and the well spacing between the injection and production wells in the well pattern system is 50-100 m.
3. The oil shale in-situ mining reaction zone control system of claim 1, wherein: the supercharger (31) is a four-stage piston compressor.
4. The oil shale in-situ mining reaction area control process method is characterized in that shale oil and gas mining is carried out on the basis of the oil shale in-situ mining reaction area control system of claim 1, 2 or 3, and the method specifically comprises the following steps:
selecting an oil shale in-situ mining block, drilling seven injection-production wells in the selected oil shale in-situ mining block to form a regular hexagon seven-point well network, and putting a logging instrument and a logging instrument into a central injection-production well to determine a target interval of an oil shale layer (2);
performing multiple fracturing constructions in separate wells in the injection and production wells to complete reservoir transformation of the oil shale layer (2), performing inter-well connectivity test after the fracturing fluid is drained back, and entering the next step after the test is qualified;
step three, after the underground heater (13) and the copper-clad cable are connected on the ground and installed in a sealing mode, the copper-clad cable penetrates through the injection and production well head (11), after the oil pipe (12) is connected with the underground heater (13), the tower crane enters the field to lower the underground heater (13) into the injection and production well, the underground heater (13) is completed, and the injection and production well head (11) is installed;
step four, drying the preheated oil shale layer (2): starting an underground heater (13) in the central injection and production well, setting the heating temperature of the underground heater (13) to 300 ℃, taking the central injection and production well as an injection heat well, taking six peripheral injection and production wells as production wells, and adjusting the gas injection pressure by 6-12 Mpa and the gas injection pressure by 200Nm3/h～300Nm3The gas injection flow rate can be adjusted to inject 300 ℃ high-temperature nitrogen into the target interval of the oil shale layer (2), the 300 ℃ high-temperature nitrogen is used as a heat carrier nitrogen medium to form forced convection heat transfer through a fracturing seepage channel (20), so that the temperature is reduced from high to low in a gradient manner from a central injection and production well to the surrounding injection and production well group, the pressure of the surrounding injection and production well group is maintained to be 0.3-0.8 Mpa, and the heating period is 7 days;
step five, a single-well huff and puff high-temperature heating oil shale layer (2) stage: closing the six peripheral injection and production wells, setting the heating temperature range of the downhole heater (13) in the central injection and production well to be 450-520 ℃, and setting the heating temperature range to be 6-20 Mpa injection pressure range and 200Nm3/h～300Nm3H, gas injection with technological parameters of adjustable gas injection flow, single-well huff and puff in the central injection and production well, oil shale layer (2) is heated for 24h, so that the oil shale layer (2) between the central injection and production well and the surrounding injection and production well group sequentially forms an in-situ conversion residual carbon area (15)An in-situ conversion cracking zone (16), an in-situ conversion oxidation zone (17), an in-situ conversion preheating zone (18) and an in-situ conversion drying zone (19);
sixthly, back gas injection self-heating oil shale layer (2) heating stage: closing an underground heater (13) in a central injection and production well, opening the underground heater (13) in six peripheral injection and production wells, adjusting a three-channel electric valve (37) to be communicated with an injection and production loop formed by the six peripheral injection and production wells, opening a second electric valve (38), a third electric valve (39), a fourth electric valve (40), a fifth electric valve (41), a sixth electric valve (42) and a seventh electric valve (43), taking the central injection and production well as a production well, taking the six peripheral injection and production wells as injection wells, setting the heating temperature interval of the underground heater (13) in the six peripheral injection and production wells to be 200-250 ℃, the gas injection pressure to be 10-15 MPa and the gas injection flow interval to be 25Nm3/h～50Nm3Conveying preheated air to the central injection and production well through an inner hole fracture seepage channel of the oil shale layer (2), enabling oxygen in the preheated air to perform self-heating oxidation reaction with kerogen and fixed carbon in oil shale in the in-situ conversion cracking area (16) and the in-situ conversion oxidation area (17) to release heat, separating out oil and gas products, reversely passing through the in-situ conversion carbon residue area (15), and extracting the oil and gas products to the ground through the central injection and production well, wherein the extraction period is 3-4 days;
seventhly, a normal-temperature back gas injection self-heating reaction stage: the underground heater (13) in the injection and production well around the six ports is closed, the gas injection pressure can be adjusted by 10-15 Mpa at normal temperature and 25Nm3/h～50Nm3The technological parameters of the gas injection flow can be adjusted to continuously inject air, so that the in-situ conversion carbon residue zone (15), the in-situ conversion cracking zone (16), the in-situ conversion oxidation zone (17), the in-situ conversion preheating zone (18) and the in-situ conversion drying zone (19) gradually evolve from the central injection-production well to the peripheral injection-production well group, and the mining period is 3-4 days;
step eight, a high-pressure shale oil-gas displacement stage: the gas injection pressure of the surrounding injection and production wells can be adjusted at normal temperature and 10-20 Mpa, and the gas injection pressure is 50Nm3/h～100Nm3The injection flow can be adjusted, air is continuously injected, the residual oil gas products in the target interval of the oil shale layer (2) are displaced to a central injection-production well and extracted to the surface of the earth for separation, and the gas injection period is carried outThe period is 12h, and the exploitation of the target interval of the underground oil shale layer (2) is completed;
and step nine, after construction is finished, opening all injection and production well annuluses, evacuating gas in all the injection and production wells, opening injection and production well heads (11) in all the injection and production wells, completing the recovery work of oil pipes (12), underground heaters (13) and copper cables, cementing and sealing the central injection and production well, and performing shale oil and gas exploitation of the next oil shale in-situ exploitation block by taking the peripheral injection and production wells as the well arrangement of the adjacent blocks.
5. The oil shale in-situ mining reaction zone control process method as claimed in claim 4, wherein: in the fourth step, the gas injection temperature is kept constant all the time, and the gas injection pressure and the gas injection flow at the initial stage of gas injection are respectively selected from a gas injection pressure interval of 6 Mpa-12 Mpa and a gas injection flow interval of 200Nm3/h～300Nm3The lowest value of the interval of/h, the formation thermal expansion and thermal stress increase along with the formation temperature rise, the gas injection pressure is 3 Mpa/time, and the gas injection flow is 50 Nm/time3The/h gradient increases.
6. The oil shale in-situ mining reaction zone control process method as claimed in claim 4, wherein: in the fifth step, in the initial stage of gas injection, the minimum value of each interval is selected according to the gas injection temperature, the gas injection pressure and the gas injection flow, the minimum value is increased according to the formation thermal expansion and the thermal stress effect, the gas injection temperature is 20 ℃/times, the gas injection pressure is 5 Mpa/time, and the gas injection flow is 50 (Nm)3Adjustment is carried out in/h)/step-by-step gradient increase.
7. The oil shale in-situ mining reaction zone control process method as claimed in claim 4, wherein: in the sixth step, the minimum value of each interval is selected according to the gas injection temperature, the gas injection pressure and the gas injection flow at the initial injection stage, the gas migration from the central injection-production well to the peripheral injection-production wells is smooth, the temperature is 20 ℃/times, the gas injection pressure is 2 Mpa/time, and the gas injection flow is 10 (Nm)3And/h)/step-by-step stepwise increase.
8. According to claim 4The process method for controlling the oil shale in-situ mining reaction area is characterized by comprising the following steps: and seventhly, selecting the minimum value of each interval from the gas injection pressure and the gas injection flow at the initial injection stage, wherein the gas injection pressure is 2 Mpa/time and the gas injection flow is 10 Nm/time according to the smooth gas migration condition from the central injection-production well to the peripheral injection-production wells3And/h is adjusted in step-by-step increasing.
9. The oil shale in-situ mining reaction zone control process method as claimed in claim 4, wherein: in the eighth step, the minimum value of each interval is selected according to the gas injection pressure and the gas injection flow at the initial injection stage, the gas injection pressure is 10 Mpa/time and the gas injection flow is 50 (Nm) according to the oil and gas displacement condition from the central injection-production well to the peripheral injection-production wells3H)/step-by-step ascending adjustment.
10. The shale oil and gas in-situ recovery reaction zone control process method of claim 4, wherein when the surrounding injection and production well group is used as an injection well or a production well, the pressure in the wells is maintained to be greater than or equal to 0.3MPa, so that an isobaric gas drive closed boundary (14) is formed.
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