CN114109323B - Method for developing low-maturing shale oil by injecting air through-put - Google Patents
Method for developing low-maturing shale oil by injecting air through-put Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 50
- 239000003079 shale oil Substances 0.000 title claims abstract description 33
- 239000004058 oil shale Substances 0.000 claims abstract description 76
- 238000010438 heat treatment Methods 0.000 claims abstract description 44
- 238000004519 manufacturing process Methods 0.000 claims abstract description 35
- 238000002347 injection Methods 0.000 claims abstract description 32
- 239000007924 injection Substances 0.000 claims abstract description 32
- 230000002706 hydrostatic effect Effects 0.000 claims description 16
- 239000012530 fluid Substances 0.000 claims description 6
- 230000015572 biosynthetic process Effects 0.000 claims description 5
- 238000009933 burial Methods 0.000 claims description 4
- 238000012544 monitoring process Methods 0.000 claims description 4
- 238000012216 screening Methods 0.000 claims description 4
- 238000012806 monitoring device Methods 0.000 claims description 3
- 230000000630 rising effect Effects 0.000 claims description 3
- 238000005553 drilling Methods 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- 238000011161 development Methods 0.000 abstract description 14
- 230000000694 effects Effects 0.000 abstract description 14
- 238000011065 in-situ storage Methods 0.000 abstract description 13
- 238000012986 modification Methods 0.000 abstract description 9
- 230000004048 modification Effects 0.000 abstract description 9
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- 238000003776 cleavage reaction Methods 0.000 abstract description 3
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- 230000003647 oxidation Effects 0.000 abstract description 3
- 238000007254 oxidation reaction Methods 0.000 abstract description 3
- 230000007017 scission Effects 0.000 abstract description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 230000001737 promoting effect Effects 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 40
- 239000010410 layer Substances 0.000 description 24
- 238000000197 pyrolysis Methods 0.000 description 14
- 230000008569 process Effects 0.000 description 12
- 238000005516 engineering process Methods 0.000 description 8
- 230000035699 permeability Effects 0.000 description 8
- 238000005485 electric heating Methods 0.000 description 6
- 238000003763 carbonization Methods 0.000 description 5
- 239000005416 organic matter Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 239000011148 porous material Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- 239000010426 asphalt Substances 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- 235000002568 Capsicum frutescens Nutrition 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 244000191502 Chenopodium murale Species 0.000 description 1
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- CVSVTCORWBXHQV-UHFFFAOYSA-N creatine Chemical compound NC(=[NH2+])N(C)CC([O-])=O CVSVTCORWBXHQV-UHFFFAOYSA-N 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000009969 flowable effect Effects 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 239000003864 humus Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
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- 238000005065 mining Methods 0.000 description 1
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- 238000012360 testing method Methods 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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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
- E21B43/166—Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
- E21B43/168—Injecting a gaseous medium
-
- 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
-
- 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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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
The invention discloses a method for developing low-temperature shale oil by injecting air through-put. According to the method, the air injection oxidation mode is adopted, the oil shale is effectively combusted to form a cavity with a certain volume, the cavity volume is directly related to the injection air quantity, namely, after each injection air ignition, new oil shale can be combusted to form a new cavity, so that the injection air quantity of each round can be increased, the heating range is larger after ignition, and more oil gas is produced. And the air is injected at high pressure, and the pulse operation of low-pressure open flow production is beneficial to promoting the cleavage and opening of the deep part of the oil shale, and improving the shale oil gas production. The method for developing shale oil by injecting air can produce a large amount of oil gas in the multi-round air injection throughput, promote the cavity to form communication among wells, effectively enlarge the control range of a single well, then convert into more efficient displacement operation, gradually enlarge the volume of the cavity, and gradually improve the integral development effect of the shale oil. Compared with the existing oil shale in-situ modification development effect, the method has the advantage that the in-situ modification development effect of the oil shale is greatly improved.
Description
Technical Field
The invention relates to the field of shale oil exploitation, in particular to a method for developing low-temperature shale oil by injecting air through-put.
Background
Oil shale (oil shale) is rich in organic matters (usually about 15% -50%), and has high ash content>40 wt.%) of a combustible sedimentary rock of humidities, humus or mixed organic and inorganic minerals, with a density of 1.4-2.7 g/cm 3 Between them. The oil shale contains two organic matters: firstly, asphalt is soluble in organic solvents, and the relative content of the asphalt is small and is about several percent of organic matters; the other is a high molecular polymer insoluble in organic solvents, called kerogen. The shale with the oil content of more than 3.5 percent per ton is internationally called oil shale, most of the oil shale contains 3.5 to 15 percent of natural petroleum, a small amount of the oil shale is more than 20 percent, and the oil shale has industrial value and heat productivity only when the organic matter content is more than 5 percent4186.8-16747.2 KJ/kg. The global oil shale resources are quite abundant, the resource reserves are about 10 trillion tons, the countries with the resource reserves exceeding 10 trillion tons are the United states, russian, brazil, morocco, jordan, australia, edania, china and the like, and the total amount is about 3741 trillion tons, accounting for 78.76 percent of the total amount of the world shale oil resources. The geologic age produced by the deposit is mainly distributed in the ancient, chilies, the Ornithogaly, the volunteer, the clay, the carbolic, the two-fold, the middle-aged, the three-fold, the Jurassic, the chalky, the third of the new generation, and so on, mainly in the land. The generation of large oil shale deposits is mainly based on the third century of new generation, such as the U.S. green river basin, the Songliao basin, australian Siderurgica Alt, etc.
Oil shale resources are used for extracting shale oil through a thermal processing technology, and the method is an effective means for developing and utilizing the oil shale. Pyrolysis, also known as retorting or thermal decomposition, refers to the complex process of heating a pyrolysate in the absence of air, and causing a series of physical changes and chemical reactions at different temperatures to produce shale oil and gas and residues. The pyrolysis process is critical to obtaining shale oil.
The pyrolysis oil production process of oil shale can be classified into an above-ground pyrolysis method and an underground pyrolysis method. The ground pyrolysis process is a process that oil shale is mined in the open or underground, sent to the ground, crushed and screened to the required granularity or block size, and enters a carbonization furnace for pyrolysis so as to obtain shale oil gas and residues. The oil shale ground carbonization technology is mature, but has the problems of low utilization rate, high pollution, small scale, high cost, large amount of waste residues generated by a carbonization furnace, land occupation, difficult treatment and the like.
Under the background, an in-situ pyrolysis process is provided, wherein the in-situ pyrolysis process is a novel technology for directly heating underground oil sheets, collecting produced oil gas, conveying the produced oil gas to the ground, and condensing to obtain shale oil and noncondensable gas. The in-situ pyrolysis process (insitu returning) is used for exploiting shale oil, mining and building large tail gas treatment facilities are not needed, deep and high-thickness oil shale resources can be developed, and the method has the advantages of good product quality, high oil extraction rate, small occupied area, environmental friendliness and the like, and is widely studied at home and abroad, and is currently in an industrial test stage.
According to the heating mode, the oil shale in-situ exploitation technology can be divided into more than ten technologies such as conduction heating, convection heating and radiation heating.
The oil shale in-situ pyrolysis technology needs to solve the following 3 problems: (1) kerogen must be converted to flowable liquid hydrocarbon petroleum and pyrolysis gas. Providing enough heat in a certain underground area, and ensuring pyrolysis to occur within reasonable temperature and time so as to complete the conversion process; (2) pore-permeation property modification is carried out on the dense low-permeability oil shale layer wrapping the kerogen so as to increase permeability; (3) the oil shale residue remained underground after carbonization does not pollute the environment.
In the three in-situ exploitation technologies, the conduction heating speed is low, the heating time is long, the heat loss is large, the cost is high, and due to the thermal expansion of the oil shale, partial cracks are closed, the permeability of the oil shale is reduced, so that the oil and gas recovery ratio is reduced. In contrast, the convection heating of oil shale is faster but not easy to control, the cracks generally do not close due to the effect of fluid pressure, the oil gas is led out faster, but short circuit of fluid is easy to form, and the recovery ratio is low. The radio frequency heating penetration force is strong, the heating speed is high, but the cost is high, and the technical difficulty is high.
Because the initial pore permeability of the oil shale stratum is poor, in order to smoothly lead out the carbonization gas, the oil shale stratum needs to be fractured, and the porosity and the permeability of the oil shale stratum are increased so as to improve the recovery ratio of shale oil.
Disclosure of Invention
Based on the background technology, the invention provides a method for developing low-temperature shale oil by injecting air through, which can effectively reduce energy consumption in the shale oil development process, improve heating efficiency, expand heating range, improve the property of produced fluid and improve the shale oil development effect.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the invention provides a method for developing low-temperature shale oil by injecting air through-put, which comprises the following steps:
1) Screening a target area and a horizon;
2) Drilling a vertical well or a horizontal well from the ground to penetrate through the oil shale layer according to the distribution characteristics of the oil shale layer;
3) Setting a packer in a vertical well or a horizontal well section, and setting an electric heater and a temperature monitoring device in a well shaft;
4) Starting an electric heater to heat and monitor the temperature and pressure rising condition, and releasing the wellhead pressure when the wellhead pressure reaches 0.3-1 times of hydrostatic pressure; at the moment, air is injected, and injection is stopped after the injection pressure reaches 1.8-2.0 times of the hydrostatic pressure of the stratum; continuously heating and monitoring the layer temperature of the oil shale;
5) When the temperature of the oil shale layer suddenly rises, the electric heater is turned off; after the temperature of the oil shale layer is increased, the temperature begins to drop to 400-500 ℃, the production is carried out by open-hole self-injection, and injected gas and formation fluid at the bottom of the well are extracted; the daily gas production temperature is reduced to below 200 ℃ and the daily gas production is less than 200m 3 And/d, closing the well to stop production;
6) Starting an electric heater, heating for 2-10 days, and injecting air into the bottom of the well to achieve 1.8-2.0 times of hydrostatic pressure; continuing heating and monitoring the temperature and pressure rise;
7) And (5) when the temperature of the oil shale layer is suddenly increased, repeating the steps 5-6, and stopping production until the economic limit is reached.
Each step is described in detail below:
step 1): target regions and horizons are screened.
According to the method of the present invention, preferably, the conditions for screening the target region and the horizon include: the burial depth is 500-3000 m, the Ro value range is 0.5-1.0%, the mass content of organic matters is more than 10%, the water saturation is less than 10%, and the thickness is more than 10m.
Step 2): according to the oil shale horizon distribution characteristics, a vertical well or a horizontal well is drilled from the ground to penetrate through the oil shale stratum.
According to the method of the invention, preferably, the vertical well adopts a perforation completion mode or an open hole completion mode, and the horizontal well adopts a screen pipe completion mode.
Step 3): and (3) setting a packer in a vertical well or a horizontal well section, and setting an electric heater and a temperature monitoring device in a well shaft.
According to the method of the invention, preferably, the power of the electric heater is designed to be more than 100KW, and the heating temperature of the electric heater is in the range of 500-700 ℃.
According to the method of the present invention, preferably, the electric heater employs a thermocouple.
Step 4): starting an electric heater to heat and monitor the temperature and pressure rising condition, and releasing the wellhead pressure when the wellhead pressure exceeds 0.3-1 times of hydrostatic pressure; at the moment, air is injected, and injection is stopped after the injection pressure reaches 1.8-2.0 times of the hydrostatic pressure of the stratum; heating is continued and the oil shale horizon temperature is monitored.
The pressure of the wellhead is released, and hydrocarbon gas which is heated and separated from shale oil is released and is endowed in the oil shale in an adsorption state. A hydrostatic pressure of 0.5 to 1 times is selected, as too high a pressure would prevent the release of the gas from the oil shale. For shale oil reservoirs with depth less than 500m, the hydrostatic pressure is small and can reach 1 time of the hydrostatic pressure; for depths >2000m, the hydrostatic pressure is large, and can be properly controlled to be about 0.3 times.
According to the method of the present invention, preferably, the injection of air is started when the pressure is released in step 4) to a wellhead pressure below 5 atm. And stopping injection after the injection pressure of the injected air reaches 1.8-2.0 times of the hydrostatic pressure of the stratum so as to prevent the stratum from being excessively broken.
According to the method of the present invention, preferably, in the step 4), the heating temperature is set to 500 to 600 ℃ when the electric heater is turned on, for example, 550 ℃ in the embodiment.
According to the method of the present invention, preferably, in the step 4), the air injection speed of the injected air is 10000 to 20000 square/day.
Step 5): when the temperature of the oil shale layer suddenly rises, the electric heater is turned off; after the temperature of the oil shale layer is increased, the temperature begins to drop to 400-500 ℃, the production is carried out by open-hole self-injection, and injected gas and formation fluid at the bottom of the well are extracted; the daily gas production temperature is reduced to below 200 ℃ and the daily gas production is less than 200m 3 And/d, closing the well to stop production.
According to the method of the present invention, preferably, in step 5), the electric heater is turned off when the temperature of the oil shale layer suddenly rises by more than 100 ℃ within 1 hour.
Step 6): starting an electric heater, heating for 2-10 days, and injecting air into the bottom of the well to achieve 1.8-2.0 times of hydrostatic pressure; heating was continued and monitored for temperature and pressure rise.
According to the method of the present invention, preferably, in step 6), the heating temperature set by turning on the electric heater is 500 to 600 ℃, for example, 550 ℃ in the embodiment.
Step 7): and (5) when the temperature of the oil shale layer is suddenly increased, repeating the steps 5-6, and stopping production until the economic limit is reached.
Preferably, in step 7), the ratio of the volume of gas produced to the volume of injected air is less than or equal to 0.12 by the time the economic limit is reached. The ratio of the volume of produced gas to the volume of injected air is related to the efficiency, e.g. the price of produced gas can be sold to 3 yuan/m 3 About, the cost of the injected air is 0.3 yuan/m 3 And the production is stopped when the ratio of the volume of the produced gas to the volume of the injected air is less than or equal to 0.1, and the specific volume ratio is determined according to the local price of the relevant material at the time.
After the multi-pass huff and puff, communication is promoted to be formed among wells, the control range of a single well is effectively enlarged, displacement operation can be carried out, the volume of a cavity is gradually enlarged, and the integral development effect of shale oil is gradually improved. Compared with the existing oil shale in-situ modification development effect, the method has the advantage that the in-situ modification development effect of the oil shale is greatly improved.
Compared with the existing electric heating method, the method for developing shale oil by air injection assistance provided by the invention has the advantages that:
1) The method of exploiting low-temperature shale oil by injecting air oxidation provides in-situ generated heat to heat the stratum, and the formed heat source is closer to the original oil shale area, so that heating is more effective. The heating cable in the invention is mainly used for the ignition process, and not the main heating mode. In general, in the electric heating method, the ignition cable is generally required to be in a high-temperature state for a long time, and a large amount of electric energy is consumed.
2) The oil shale is effectively combusted into a cavity with a certain volume in an air injection oxidation mode, and the volume of the cavity is directly related to the air injection quantity, namely, after each air injection ignition, new oil shale can be combusted to form a new cavity. Therefore, the injection air quantity of each round can be increased, the heating range after ignition is larger, and more oil gas is produced. However, the general electric heating method can only heat organic matters within a limited range (radius is about 5 m), so that only well patterns with extremely high density (well spacing is 5-7 m) can be designed and developed.
3) The oil shale burns to consume impurities such as tar, coke and the like remained after kerogen pyrolysis, so that the improvement of stratum pore permeability property is promoted; in the general electric heating process, the pyrolyzed impurities are continuously stored in the pores and are mixed with clay particles, so that the pore permeability is not obviously improved.
4) The pulse operation of air high-pressure injection and low-pressure open flow production is beneficial to promoting the cleavage and opening of the deep part of the oil shale and improving the shale oil and gas production. The volumetric expansion of the oil gas generated by heating in the general electric heating process increases the pressure, and the shortcoming is that the organic matter conversion environment keeps high pressure, slows down the speed of organic matter conversion, and causes cleavage early sealing and influences the production effect along with the decrease of the underground pressure of the oil gas output.
5) The method for exploiting shale oil by injecting air can produce a large amount of oil gas in the multi-round air injection throughput, promote the cavity to form communication among wells, effectively enlarge the control range of a single well, then convert into more efficient displacement operation, gradually enlarge the volume of the cavity, and gradually improve the integral development effect of the shale oil. Compared with the existing oil shale in-situ modification development effect, the method has the advantage that the in-situ modification development effect of the oil shale is greatly improved.
Detailed Description
In order to more clearly illustrate the present invention, the present invention will be further described with reference to preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and that this invention is not limited to the details given herein.
All numerical designations of the invention (e.g., temperature, time, concentration, weight, etc., including ranges for each) can generally be approximations that vary (+) or (-) as appropriate in 0.1 or 1.0 increments. All numerical designations are to be understood as preceded by the term "about".
Example 1
The embodiment provides application of deep low-temperature shale oil injection air throughput development with the depth of about 1000 m.
Reservoir Properties introduction:
the oil shale reservoir of the reservoir 1 has burial depth of 1030m, the effective thickness of the reservoir is 20.0m, the oil shale is continuously and stably distributed, ro=0.6% is high-quality medium-low-matured shale oil, and the organic matter content reaches 14%. The inside of the oil shale layer is free of a pure mud rock interlayer, and the upper part of the oil shale layer is provided with a better cover layer; the bottom has a mud layer with a permeability of only 0.01md.
The method for developing shale oil by injecting air specifically comprises the following steps:
1) According to the geological features and the development status of the reservoir, performing initial evaluation:
the reservoir meets the following conditions: the thickness of the oil shale layer is 20.0m, the top cover layer of the reservoir layer is developed, gas escape can be effectively prevented, the maturity is moderate, the organic matter content is high, and the oil shale layer can be used as a good target layer.
2) Horizontal wells are drilled through the oil shale formation in the formation. The upper portion of the oil shale was completed with 7 inch casing. The oil shale is partially completed by a sieve tube, and the horizontal section is 600m long.
3) A thermocouple was lowered into the wellbore to the upper portion of the horizontal section, and a 600m length of heating cable was lowered.
4) Setting the temperature of the heater at 550 ℃, starting to start heating, and observing the change conditions of the wellhead casing pressure and the bottom hole temperature.
5) After 22 days of heating, the wellhead casing pressure was raised to 1 times the hydrostatic pressure (10 MPa) and the bottom hole temperature was maintained at 550 ℃. At this time, the wellhead was opened to release gas, and production was stopped until the gas production was reduced to 200 square/day, and gas production was accumulated 67000 square. The injection of air was started at 2 square per day, and the wellhead pressure reached 1.8 times the hydrostatic pressure (18 MPa) at 45 square. Stopping injecting air; heating is started, after 23 hours of heating, the thermocouple starts to generate temperature jump, the instantaneous temperature exceeds 600 ℃, and the heater is turned off at the moment; the oil shale layer temperature is continuously monitored.
6) After 74 hours, the oil shale layer temperature began to drop gradually and slowly. At the moment, the oxygen in the oil shale layer is considered to be consumed, and the production is performed by open hole and self-injection. After the flue gas is discharged, the daily gas yield is measured to be more than 10000 square, the yield starts to drop after the stable gas yield is maintained for 3 months, and the yield drops to 200 square/day after 6 months, and the wellhead pressure is 0.5MPa.
7) At this point, the second round of air injection throughput operation is started. The air is injected in 85 square directions, and the wellhead pressure reaches 19MPa. The thermocouple was turned on, the heating temperature was set to 550 ℃, and the bottom hole temperature and wellhead pressure were monitored.
8) After heating for 75 hours, the temperature of the oil shale layer is jumped to 583 ℃, and the wellhead casing pressure has small fluctuation; at this time, the heating was stopped. After 98 hours, the oil shale horizon temperature began to decrease, and after 128 hours, the oil shale temperature was restored to around 550 ℃.
9) Open-well production, initial gas production speed 50000m 3 On day, the composition was mainly nitrogen (82%), CO 2 (12％)，CH 4 (5%); after 20 days of production, the daily gas yield is measured to be more than 30000 square, the methane/ethane content exceeds 80%, the stable production is continued for 112 days, then the yield starts to drop, after 8 months, the yield is reduced to 200 square/day, and the wellhead pressure is 0.5MPa.
10 Air injection and heating operations were continued for 6 rounds, with an accumulated injection air amount of 893 square meters and an accumulated methane and air mixture of 2300 square meters.
The production effect is deteriorated from the fifth round, the volume ratio of the accumulated produced gas/injected gas is 2.8, and the volume ratio of the sixth produced gas/injected gas is 0.12, and the production is stopped at this time.
The other well which is far from the well by 100m adopts a conventional electric heating modification production method, the peak output oil-gas mixture amount is only about 5000, and the stable production time is only 4-5 months to discard due to the deep burial, the poor permeability and the small heating range. Compared with the conventional method, the development mode of the invention brings continuous high yield and stable yield of the oil shale reservoir, and effectively improves the production effect of shale oil.
It should be understood that the foregoing examples of the present invention are provided merely for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention, and that various other changes and modifications may be made therein by one skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims.
Claims (6)
1. A method for developing low-profile shale oil by injecting air through-put, the method comprising the steps of:
1) Screening a target area and a horizon; the conditions for screening the target area and the horizon comprise: the burial depth is 500-3000 m, the Ro value range is 0.5-1.0%, the mass content of organic matters is more than 10%, the water saturation is less than 10%, and the thickness is more than 10m;
2) Drilling a vertical well or a horizontal well from the ground to penetrate through the oil shale layer according to the distribution characteristics of the oil shale layer;
3) Setting a packer in a vertical well or a horizontal well section, and setting an electric heater and a temperature monitoring device in a well shaft;
4) Starting an electric heater to heat and monitor the temperature and pressure rising condition, and releasing the wellhead pressure when the wellhead pressure reaches 0.3-1 times of hydrostatic pressure; air is injected when the pressure is released until the wellhead pressure is lower than 5atm, and injection is stopped after the injection pressure reaches 1.8-2.0 times of the hydrostatic pressure of the stratum; continuously heating and monitoring the layer temperature of the oil shale;
5) When the temperature of the oil shale layer suddenly rises to more than 100 ℃ within 1 hour, the electric heater is turned off; after the temperature of the oil shale layer is increased, the temperature begins to drop to 400-500 ℃, the production is carried out by open-hole self-injection, and injected gas and formation fluid at the bottom of the well are extracted; the daily gas production temperature is reduced to below 200 ℃ and the daily gas production is less than 200m 3 And/d, closing the well to stop production;
6) Starting an electric heater, heating for 2-10 days, and injecting air into the bottom of the well to achieve 1.8-2.0 times of hydrostatic pressure; continuing heating and monitoring the temperature and pressure rise;
7) And when the temperature of the oil shale layer suddenly rises, repeating the steps 5-6 until the economical limit is reached, namely, the ratio of the volume of the produced gas to the volume of the injected air is less than or equal to 0.12, and stopping production.
2. The method of claim 1, wherein in step 2), the vertical well is perforated or open hole, and the horizontal well is screen.
3. The method according to claim 1, wherein the power of the electric heater is designed to be more than 100KW, and the heating temperature of the electric heater is in the range of 500-700 ℃.
4. The method according to claim 1, wherein in step 4), the heating temperature is set to 500 to 600 ℃ when the electric heater is turned on.
5. The method according to claim 1, wherein in the step 4), the air injection speed of the injected air is 10000 to 20000 square/day.
6. The method according to claim 1, wherein in step 6), the heating temperature is set to 500 to 600 ℃ when the electric heater is turned on.
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| CN102444397A (en) * | 2011-10-24 | 2012-05-09 | 国鼎(大连)投资有限公司 | Method of exploiting deep layer oil shale to manufacture shale oil and oil shale gas |
| CN108825193A (en) * | 2017-05-05 | 2018-11-16 | 中国石油化工股份有限公司 | Oil shale in-situ recovery method |
| CN109339755A (en) * | 2018-12-03 | 2019-02-15 | 中国石油大学(北京) | A kind of method and device thereof improving fine and close rock oil recovery |
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| CN102444397A (en) * | 2011-10-24 | 2012-05-09 | 国鼎(大连)投资有限公司 | Method of exploiting deep layer oil shale to manufacture shale oil and oil shale gas |
| CN108825193A (en) * | 2017-05-05 | 2018-11-16 | 中国石油化工股份有限公司 | Oil shale in-situ recovery method |
| CN109339755A (en) * | 2018-12-03 | 2019-02-15 | 中国石油大学(北京) | A kind of method and device thereof improving fine and close rock oil recovery |
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