Efficient development method for thin coalbed methane well

Abstract

This invention relates to the field of coalbed methane well development technology, and particularly to a method for efficient development of thin-layer coalbed methane wells. The method includes the following steps: Step 1. Drilling and completion of the well, which is a directional well; Step 2. Performing at least two large-scale fracturing operations with a fracturing flow rate of 16-20 m³ / h. 3 / min, single sand addition amount 400-600m³ 3 The volume of fracturing fluid used in a single operation is 3000-4000 m³. 3 The final fracturing stage, involving the carrying of sand and fluid, is accompanied by fiber injection; during each fracturing interval, water injection is used to maintain pressure, injecting water into the formation at a small rate to ensure that the formation pressure is not lower than the fracture closure pressure; step 3. Rapid fluid drainage is used to reduce pressure and drain the gas. This invention improves the utilization of single-layer resources in coalbed methane directional wells through large-scale, multi-round fracturing, thereby significantly increasing single-well production and achieving gas production capacity similar to horizontal wells. Simultaneously, based on large-scale modification of thin coal seams, it optimizes coalbed methane drainage methods, significantly shortens the gas emergence period, and enables continuous and stable production, achieving efficient development of thin coal seams.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coalbed methane well development, in particular to a high-efficiency development method for thin coalbed methane well. BACKGROUND

[0002] Coalbed methane resource is huge, according to statistics, the coalbed methane geological resource amount of 2000m shallow in China reaches 36.8x10 12 m 3 As a non-conventional clean energy, the high-efficiency development of coalbed methane has a very important significance for guaranteeing the energy supply of China.

[0003] The development steps of coalbed methane are generally divided into three stages. Firstly, drilling, through continuous field practice, the drilling mode of directional well as the main and horizontal well as the auxiliary is formed in China, the single well production of horizontal well is high, but due to the cost rising than directional well, the economic benefit has no obvious advantage; secondly, fracturing, the characteristics of low porosity and low permeability of coalbed methane determines that it must be reformed by fracturing to produce gas.

[0004] The common fracturing technology of coalbed methane at present is active water fracturing technology, the fracturing fluid takes reducing coal seam damage and increasing flowback as the target, the liquid system formula generally includes water, bactericide, cleanup additive, the pump injection displacement of 6-8m 3 / min is adopted during construction, and the sand amount is 35-50m 3 Although this fracturing technology has achieved certain reform effect, the single well production is less than expected, and cannot effectively meet the benefit development of coalbed methane; finally, drainage production, coalbed methane must be drained to produce gas, by learning from conventional oil development, the most commonly used liquid drainage technology is pumping unit + tube pump drainage, based on the consideration of coal rock reservoir protection, "sustained, slow and stable" becomes the basic principle of coalbed methane development, therefore, the coalbed methane well generally needs to be drained for about 2 years to reach stable production capacity, the drainage effect is slow, the investment risk is greatly improved, which seriously restricts the large-scale development of coalbed methane.

[0005] CN108240209B discloses a method for secondary fracturing of a coalbed methane well, which comprises the following steps: starting a fracturing truck group, and pumping fracturing fluid into a target coalbed methane well through the fracturing truck group to perform small-scale fracturing to dredge the original fractures in the reservoir. A plurality of blocking balls less than the number of perforation holes are put into the target coalbed methane well, and at the same time, active water fracturing fluid is pumped into the target coalbed methane well by using the fracturing truck group, and the blocking balls block the perforation holes of the original fractures under the pressure of the active water fracturing fluid. The fracturing truck group is used to continue pumping fracturing fluid into the target coalbed methane well to perform medium-scale fracturing, and new fractures are formed in the reservoir. After the blocking balls fall into the bottom of the well after leaving the perforation holes, the blocking balls are flowed back to the ground, and the secondary fracturing is completed. The method mainly solves the problem of low gas production caused by small initial fracturing range of the coalbed methane well.

[0006] CN109209320B discloses a secondary fracturing method for a coalbed methane well, which comprises the following steps: obtaining a sonic travel time logging curve of the coalbed methane well and a depth range of a coalbed section of a formation where the coalbed methane well is located; determining a depth range of a roof section of the coalbed methane well according to the sonic travel time logging curve and the depth range of the coalbed section, and determining a perforation position on the roof section; blocking a first perforation hole below the perforation position; performing perforation to form a second perforation hole at the perforation position; and injecting fracturing fluid into a wellbore of the coalbed methane well, so that the fracturing fluid enters a formation of the roof section through the second perforation hole, and then cracks are generated in the roof section and the formation between the roof section and the coalbed section. The method generates cracks that communicate the primary fracturing cracks and the natural cleat cracks of the coalbed by generating cracks in the coalbed roof and the formation between the coalbed roof and the coalbed section, thereby improving the permeability of the coalbed where the coalbed methane well is located.

[0007] CN111931114B discloses a method for quickly deciding a coalbed methane well for repeated fracturing, which comprises the following steps: step 1, obtaining drilling coalbed data, initial fracturing data and production dynamic data of each candidate coalbed methane well; step 2, calculating a repeated fracturing well selection comprehensive evaluation index of each candidate coalbed methane well; and step 3, determining a coalbed methane well with greater repeated fracturing potential according to a sorting result of the repeated fracturing well selection comprehensive evaluation index. The method mainly realizes quick decision of a coalbed methane well for repeated fracturing.

[0008] Compared with conventional coalbed methane development, the thickness of a thin coalbed is less than 3 m, the resource abundance is lower under the condition that the gas content is not much different from that of a conventional coalbed, and the development of benefits is more difficult under the background of common problems in coalbed methane development. SUMMARY

[0009] To solve the above problems, the present application provides a thin coalbed methane well efficient development method. The method improves the single layer resource producing degree of the coalbed methane directional well through large-scale and multi-round fracturing, thereby greatly improving the single well production, realizing the gas production capacity of the coalbed methane directional well similar to the horizontal well, and on the basis of realizing the large-scale reconstruction of the thin coal seam, optimizing the coalbed methane drainage method, greatly shortening the gas appearance period and being able to continuously and stably produce, realizing the benefit development of the thin coal seam.

[0010] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0011] The present application provides a thin coalbed methane well efficient development method, which comprises the following steps:

[0012] Step 1. Drilling and well completion, the well type is a directional well;

[0013] Step 2. Large-scale fracturing is carried out at least twice, the construction discharge is 16-20 m 3 / min, the single sand adding amount is 400-600 m 3 , the single fracturing fluid amount is 3000-4000 m 3 ; the fiber is injected during the sand-carrying fluid stage of the last fracturing; water injection is adopted for pressure maintenance during the interval of each fracturing, and water is injected to the formation at a small discharge, so as to ensure that the formation pressure is not lower than the fracture closure pressure;

[0014] Step 3. The depressurization drainage is carried out in the way of rapid liquid discharge.

[0015] The construction discharge of the present application can improve the net pressure in the fracture, open more micro-fractures, improve the fracture complexity, and increase the proppant migration efficiency, and the sand adding amount and the fluid amount can ensure the length of the fracture extension and the radius of the effective support under the condition of the opening of the complex fracture network.

[0016] Further, in step 2, the main proppant of the fracturing is 40-70 mesh quartz sand.

[0017] Further, the fiber is injected in the way of slug injection during the sand-carrying fluid stage of the last fracturing. The purpose of injecting the fiber is that the sand production of the formation is more serious in the later stage of the drainage as the sand adding amount increases, the fiber can wrap the sand particles to form large particle combinations, increase the critical flow velocity of the sand particles, and thus a good sand prevention effect is achieved. The slug sanding can form a ladder barrier, and further increase the sand prevention effect.

[0018] Further, in step 2, the last fracturing is carried out in the way of over displacement, and the displacement amount is 3-5 times the wellbore volume. In this way, part of the fracturing sand accumulated in the near wellbore area can be further pushed to the deep part of the fracture, the distance required for the fracturing sand to migrate to the wellbore is increased, and the sand production of the formation is reduced.

[0019] Further, in step 2, the sand adding procedure of each fracturing sand carrying fluid stage adopts a stepped fast lifting mode to reach the main sand ratio stage with minimum liquid volume.

[0020] Further, in step 2, the liquid system of the fracturing fluid is drag-reducing water; the drag-reducing water comprises a drag-reducing agent and water, the mass fraction of the drag-reducing agent being 0.05%-0.1%; compared with the friction of clean water, the drag reduction rate of the drag-reducing water needs to reach more than 70% under the same displacement; and the viscosity of the drag-reducing water needs to reach more than 6 mPa.s under the minimum concentration. The drag-reducing water is used to increase the sand carrying capacity of the fracturing fluid, thereby increasing the sand migration distance of the fracturing sand and increasing the effective support length of the fracture. It should be noted that, due to the characteristics of low pressure and low permeability of the coal seam, the viscosity of the fracturing fluid should not be too large, otherwise it is not easy to flow back and is easy to cause damage to the coal seam.

[0021] Further, in step 3, the rapid liquid discharge mode is used to reduce the pressure and discharge, and the stable production capacity is reached after 1-3 months of production.

[0022] Further, in step 3, the dynamic adjustment of the pump hanging mode is used to improve the liquid discharge and gas production efficiency of the thin coal seam gas well, the first stage is mainly liquid discharge, the tubular pump is used to be lowered to 500-1000 m shallow to discharge liquid, the daily liquid production capacity needs to reach 40-80 m 3 / d; the second stage is pressure reduction and gas production, the oil pump is used to be lowered to 50-100 m of the top boundary of the coal seam to reduce the flow pressure and produce; the third stage is stable gas production, the oil pump is used to be lowered to the vicinity of the coal seam to stably discharge liquid and maintain the stable gas production of the gas well.

[0023] Compared with the prior art, the present application has the following advantages:

[0024] The thin coal seam gas well efficient development method provided by the present application provides an overall solution from drilling and completion, fracturing to discharge and production of three stages:

[0025] (1) In the aspect of drilling and completion, the directional well type is used for drilling and completion to reduce the development cost.

[0026] (2) In the aspect of fracturing, large-scale and multi-cycle fracturing is used, which can overcome the problems of strong plasticity of the coal seam and short reconstruction range, increase the reconstruction length, improve the net pressure in the fracture, open more micro-fractures and improve the complexity of the fracture, and increase the effective support length of the fracture.

[0027] The small displacement water injection is used to maintain the formation pressure during each fracturing interval, so as to ensure that the formation pressure is not lower than the fracture closure pressure, thereby reducing the amount of preflush used in the next fracturing, and promoting the extension of the fracturing fracture along the old fracture, and increasing the length of the transformation. The segment type fiber injection is used in the last sand carrying liquid stage, because with the increase of the fracturing scale, the sand production in the later stage will become more serious, the fiber is added in the sand carrying liquid stage, the fiber wraps the sand particles to form a large particle combination, which can increase the critical flow velocity of the quartz sand, and form a certain sand stabilizing effect, and the segment type sand adding is used to form a ladder barrier, and the sand prevention effect is further increased. The over displacement is used in the last fracturing displacement liquid, and the displacement liquid amount is 3-5 times of the wellbore volume, so that the amount of sand accumulated in the near wellbore zone is reduced, thereby reducing the sand production of the formation. Compared with the clear water, the drag reduction water can reduce the friction by more than 70%, which reduces the requirement for the performance of the equipment, and the drag reduction water increases the viscosity, which is helpful for sand carrying.

[0028] Through at least two large-scale fracturing, the single layer resource development degree of the thin coal seam directional well can be greatly increased, and the transformation effect similar to the horizontal well is achieved, so that the thin coal seam gas directional well can achieve the gas production capacity similar to the horizontal well.

[0029] (3) In terms of drainage, because the fracturing scheme described in the method forms a large range of effective support transformation volume, the influence of coal seam sensitivity on gas production effect is weakened, and the gas production can be carried out by means of rapid liquid drainage. According to the liquid drainage characteristics of the thin coal seam gas well at different stages, different pump diameters and different depths are used for drainage, which greatly shortens the gas breakthrough period of the thin coal seam gas well and reduces the investment recovery period.

[0030] In summary, the method of the present application improves the single layer resource development degree of the coal seam gas directional well through large-scale and multiple fracturing, thereby greatly increasing the single well production, achieving the gas production capacity similar to the horizontal well of the coal seam gas directional well, and optimizing the coal seam gas drainage method on the basis of large-scale transformation of the thin coal seam, greatly shortening the gas breakthrough period and obtaining continuous stable production, and realizing the benefit development of the thin coal seam. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0032] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0033] To solve the above problems, the present application provides a method for efficient development of thin coalbed methane wells, which comprises the following steps:

[0034] Step 1. Drilling and completion, the well type is directional well;

[0035] Step 2. Performing at least two large-scale fracturing, the construction discharge is 16-20 m 3 / min, the single sanding amount is 400-600 m 3 , and the single fracturing fluid amount is 3000-4000 m 3 . The last fracturing is accompanied by injection of fibers during the sand-carrying liquid stage. Water injection is used to maintain pressure during the interval between each fracturing, and water is injected into the formation at a small discharge to ensure that the formation pressure is not lower than the fracture closure pressure, thereby preventing the fracture from closing and reducing the amount of preflush used in the next fracturing, while promoting the extension of the fracturing fracture along the old fracture and increasing the fracture reconstruction length.

[0036] Step 3. Reducing the pressure and recovering the production by rapid liquid discharge.

[0037] As a preferred embodiment of the present application, under the fracturing scale required by the present application, generally 2-3 fracturing is performed. In actual implementation, specific adjustments can be made according to the geological and process conditions of the coal seam, but the number of fracturing should not be less than 2 to ensure a high reconstruction degree of single well and single layer. The single sanding amount and liquid amount can be adjusted according to specific circumstances, but to ensure the reconstruction effect, the single sanding amount should not differ too much from the sanding amount required by the present application.

[0038] As a preferred embodiment of the present application, in step 2, the main proppant for fracturing is 40-70 mesh quartz sand.

[0039] As a preferred embodiment of the present application, 40-70 mesh quartz sand is used for fracturing first, and then 30-50 mesh quartz sand is used for tailing and sealing in the last fracturing.

[0040] As a preferred embodiment of the present application, the fiber injection is performed in a slug mode when the fiber is injected during the sand-carrying liquid stage of the last fracturing.

[0041] As a preferred embodiment of the present application, the fiber is injected in four slugs, and the fiber injection is performed first by displacing 10-15 m 3The displacement fluid is then injected, and then the fiber is added in the original sand ratio. After the fiber is added, 10-15 m 3 of displacement fluid is injected again.

[0042] The first three times, the sand injection amount reaches 150 m 3 , 250 m 3 , and 350 m 3 , respectively, and the fiber is injected each time, with 100-200 kg of fiber being added each time; 200-300 kg of fiber is added in the fourth time, and the sand injection and fiber injection are ensured to be completed at the same time; and the fiber injection speed is 12-16 kg / min.

[0043] As a preferred embodiment of the present application, the fiber needs to meet the following requirements: a fineness of 2.0±0.2 detx, a length of 6.0±0.3 mm, a density of 1.28-1.32 g / cm 3 , and a dispersibility of ≤3 levels.

[0044] As a preferred embodiment of the present application, in step 2, the sand injection procedure in each fracturing sand-carrying fluid stage adopts a stepped fast-lifting manner to reach the main sand ratio stage with the least amount of liquid. The principle of improving the comprehensive sand-liquid ratio is used to improve the main sand ratio value as much as possible. Generally, the main sand ratio value needs to reach more than 15%, and the main sand ratio can be appropriately adjusted when special strata are encountered.

[0045] As a preferred embodiment of the present application, in step 2, the last fracturing adopts a top displacement manner, and the displacement amount is 3-5 times the wellbore volume.

[0046] As a preferred embodiment of the present application, in step 2, the liquid system used in the fracturing fluid is a drag-reducing water; the drag-reducing water includes a drag-reducing agent and water, and the mass fraction of the drag-reducing agent is 0.05%-0.1%; compared with the friction of clean water, the drag reduction rate of the drag-reducing water needs to reach more than 70% under the same displacement; and the viscosity of the drag-reducing water needs to reach more than 6 mPa.s under the minimum concentration. The present application does not make a specific limitation on the formula of the drag-reducing agent in the drag-reducing water, and the drag-reducing agent only needs to meet the three requirements of increasing the viscosity, reducing the construction friction, and being low in damage to the coal seam.

[0047] As a preferred embodiment of the present application, in step 3, the rapid liquid discharge manner is used to reduce the pressure and discharge the production, and the stable production capacity is reached after 1-3 months of production.

[0048] As a preferred embodiment of the present application, in step 3, the dynamic adjustment of the pump hanging is used to improve the liquid discharge and gas production efficiency of the thin coal seam gas well. In the first stage, the liquid discharge is mainly used, and the oil pump is lowered to 500-1000 m for shallow pumping and liquid discharge, and the daily liquid production capacity needs to reach 40-80 m 3 / d; The second stage involves reducing pressure to produce gas, using an oil pump to descend 50-100m to the top of the coal seam to reduce the flowing pressure and increase production; the third stage involves stabilizing gas production, using an oil pump to descend near the coal seam to stabilize fluid discharge and maintain stable gas production from the well. The selection of the pump hanging depth is based on the principle of rapid fluid discharge under the premise that sand production in the formation does not affect the normal operation of the pumping string, and can be adjusted according to the specific site conditions.

[0049] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0050] Example 1

[0051] A method for efficient development of thin-layer coalbed methane wells, taking well X as an example, the method includes:

[0052] Step 1. Drilling and completion: The well was drilled and completed using a directional well type. The Y-seam encountered had a vertical thickness of 1.3m, which is a typical thin coal seam.

[0053] Step 2. Perform three large-scale fracturing operations. The first fracturing operation uses 40-70 mesh quartz sand, with a drag-reducing water concentration of 0.05% and a displacement of 18m³. 3 / min, main sand ratio 17%, sand addition 501m³ 3 Fracturing fluid usage: 3413m³ 3 The second fracturing operation used 40-70 mesh quartz sand, with a drag-reducing water concentration of 0.05% and a displacement of 18m³. 3 / min, main sand ratio 17%, sand addition 501m³ 3 Fracturing fluid usage: 3285m³ 3 The third fracturing operation used a combination of 40-70 mesh quartz sand and 30-50 mesh quartz sand, with a drag-reducing water concentration of 0.05% and a displacement of 18m³. 3 / min, main sand ratio 17%, sand addition 501m³ 3 First add 451m of 40-70 mesh quartz sand. 3 50m of 30-50 mesh quartz sand in pursuit 3 Fracturing fluid usage: 3315m³ 3 .

[0054] During the third fracturing process, the sand addition rates reached 150, 250, and 350 m³, respectively. 3 At that time, each replaced 10m 3 Displacement fluid, then increase the sand ratio to 17% of the original sand ratio and inject 100 kg of fiber at a fiber injection rate of 13 kg / min. After the fiber injection is completed, continue displacement for 10 m. 3 Replacement solution, then add sand normally at 17% of the original sand ratio; when the sand addition reaches 460m³. 3 At that time, replacing 10m3 The displacement fluid is then added, and the sand ratio is increased to 17% of the original sand ratio, with 200 kg of fiber being added at a rate of 15 kg / min. After the fiber has been added, the wellbore is displaced by 3 times its volume, and the operation is completed. After the first and second fracturing operations, the formation is injected with water at a rate of 0.5 m 3 / min to maintain pressure.

[0055] The fiber needs to have a fineness of 2.0±0.2 detx, a length of 6.0±0.3 mm, a density of 1.28-1.32 g / cm 3 , and a dispersibility of ≤3 levels.

[0056] Step 3. Pressure reduction and production by rapid liquid discharge: first, a φ70 mm oil pump is used to pump to 751 m, and shallow pumping is performed at a normal daily liquid production of 50 m 3 / d; when the liquid supply is insufficient, a φ51 mm oil pump is used to pump to the top boundary of the coal seam by 100 m, and the flow pressure is reduced to increase production; when the liquid supply is insufficient, a φ44 mm oil pump is used to pump to the coal seam to stabilize liquid discharge, and gas production is maintained stable.

[0057] X well reached stable production capacity after 36 days of production, with a daily stable production of 18000 m 3 / d, and significant economic benefits.

[0058] The above embodiments are preferred embodiments of the present application, but the embodiments of the present application are not limited by the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A method for efficient development of thin-layer coalbed methane wells, characterized in that, Includes the following steps: Step 1. Drilling completed; the well type is a directional well. Step 2. Perform at least two large-scale fracturing operations, with a displacement of 16-20 m³ / h. 3 / min, single sand addition capacity 400-600m³ 3 The volume of fracturing fluid used in a single operation is 3000-4000m³. 3 The final fracturing stage with proppant-carrying fluid is accompanied by fiber injection; during each fracturing interval, water injection is used to maintain pressure, injecting water into the formation at a small rate to ensure that the formation pressure is not lower than the fracture closure pressure. Step 3. Use rapid drainage to reduce pressure and drain the sample; During the final fracturing and proppant-carrying fluid stage, fiber optic injection was performed using a slug-type injection method. The fiber is injected in four segments, with 10-15m of material pre-displaced before the fiber is injected. 3 Replace the liquid, then add the fiber at the original sand ratio. After adding the fiber, inject another 10-15m. 3 Displacement fluid.

2. The method for efficient development of thin-layer coalbed methane wells according to claim 1, characterized in that, In step 2, the proppant used for fracturing is 40-70 mesh quartz sand.

3. The method for efficient development of thin-layer coalbed methane wells according to claim 2, characterized in that, During the final fracturing operation, 40-70 mesh quartz sand was used for fracturing first, followed by 30-50 mesh quartz sand for tail sealing.

4. The method for efficient development of thin-layer coalbed methane wells according to claim 1, characterized in that, The first three times, the amount of sand added reached 150m³ each time. 3 250m 3 350m 3 When the sand and fiber are added, start adding fiber, adding 100-200kg of fiber each time; add 200-300kg of fiber for the fourth time, and ensure that the sand and fiber addition ends at the same time; the fiber addition rate is 12-16kg / min.

5. The method for efficient development of thin-layer coalbed methane wells according to claim 1 or 4, characterized in that, The fibers must meet the following requirements: fineness 2.0±0.2 detx, length 6.0±0.3 mm, and density 1.28-1.32 g / cm³. 3 Dispersion level ≤ 3.

6. The method for efficient development of thin-layer coalbed methane wells according to claim 1, characterized in that, In step 2, the sand addition procedure in each fracturing sand-carrying fluid stage adopts a stepped rapid lifting method to reach the main sand ratio stage with the minimum amount of liquid.

7. The method for efficient development of thin-layer coalbed methane wells according to claim 1, characterized in that, In step 2, the final fracturing is performed using an over-displacement method, with a displacement amount of 3-5 times the wellbore volume.

8. The method for efficient development of thin-layer coalbed methane wells according to claim 1, characterized in that, In step 2, the liquid system used for fracturing fluid is drag-reducing water; the drag-reducing water includes drag-reducing agent and water, and the mass fraction of drag-reducing agent is 0.05%-0.1%; compared with the drag of pure water, the drag reduction rate of the drag-reducing water at the same displacement needs to reach more than 70%; at the same time, the viscosity of the drag-reducing water needs to reach more than 6 mPa·s at the lowest concentration.

9. The method for efficient development of thin-layer coalbed methane wells according to claim 1, characterized in that, The pressure is reduced and the liquid is drained using a rapid drainage method. Stable production capacity is achieved 1-3 months after commissioning.

10. The method for efficient development of thin-layer coalbed methane wells according to claim 1, characterized in that, In step 3, the efficiency of fluid drainage and gas production in thin coalbed methane wells is improved by dynamically adjusting the pump setup. The first stage focuses on fluid drainage, using a pump to descend to a depth of 500-1000 meters for shallow pumping and efficient fluid drainage, with a daily fluid production capacity of 40-80 cubic meters per second. 3 / d; The second stage is to reduce pressure and produce gas by using an oil pump to go down to 50-100m above the coal seam to reduce the flow pressure and increase production; The third stage is to stabilize gas production by using an oil pump to go down to the vicinity of the coal seam to stabilize the liquid discharge and maintain stable gas production from the gas well.