A method for quickly recovering gas production after fracturing interference of a ground gas control well

Abstract

The application discloses a method for quickly recovering gas production after fracturing interference of a ground gas control well, and comprises the following steps: step S1, washing the channeling well; step S2, performing blowout treatment on the fracturing well, and simultaneously performing pressure reduction treatment on the channeling well; the blowout treatment on the fracturing well is gradually opening the valve opening degree of the well mouth of the fracturing well to perform blowout; the pressure reduction treatment on the channeling well comprises a rapid pressure reduction stage, a pressure profile recovery stage and a normal drainage stage. The method has the beneficial effect that the negative influence of the fracturing wave of the fracturing well on the channeling well is greatly reduced, the influence degree and time of the channeling well caused by the interference are better reduced, and the channeling well is successfully recovered to produce gas.

Description

Technical Field

[0001] This invention relates to the field of coal mine gas control technology, and more particularly to a method for rapidly restoring gas production after well fracturing interference in surface gas control. Background Technology

[0002] Coalbed methane (CBM) is an important clean energy source in today's society. According to relevant surveys and studies, my country has abundant CBM geological reserves, but its development is challenging due to various factors. In today's society, abundant CBM reserves are not necessarily a favorable factor for coal mining areas. They not only increase safety hazards during coal production but also raise the difficulty and cost of surface and underground gas control at different stages. Therefore, achieving coordinated development of CBM and coal, and the joint extraction of both energy resources, is of great significance for improving the resource utilization level of CBM in coal mining areas, reducing greenhouse gas emissions, preventing coal mine gas disasters, and ensuring normal mine production.

[0003] The development and management of coalbed methane in unmined coalfields has shifted from the previous vertical fracturing well technology to a more efficient development technology using horizontal wells in the roof of soft, low-permeability coal seams. However, with the deepening of coalbed methane development and the limitation of the working face width, when fracturing new wells (hereinafter referred to as fracturing wells) in old well areas, the horizontal section spacing between each well is about 200m. When the fracturing well breaks open the formation during the fracturing process, it will affect the adjacent old wells. Sometimes the fracturing fractures can extend more than 100 meters in the formation. Since the old wells have been producing for a period of time, the gas and water flow in the formation has reached a balance. When the new well fractures open the formation, the pressure on the old well side increases rapidly, the balance is disrupted, the gaps between coal seams are blocked, groundwater flows in, and fracturing sand flows in. As a result, the old wells (hereinafter referred to as fracturing wells) cannot produce normally, the horizontal section wellbore is blocked, and they cannot be restored to the gas production level before the interference or even stop producing gas altogether, resulting in low resource recovery rates.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by this invention is: how to solve the problem that the balance of the fractured well is disrupted during the fracture process, resulting in the fractured well being unable to produce normally, producing little gas, or ceasing to produce gas.

[0006] The present invention solves the above-mentioned technical problems through the following technical means:

[0007] A method for rapidly restoring gas production after fracturing interference in surface gas control wells includes the following steps:

[0008] Step S1: Wash the well to prevent channeling;

[0009] Step S2: Perform blowout treatment on the fractured well and depressurize the fractured well at the same time;

[0010] The process of releasing the blowout from a fractured well involves gradually opening the valve at the wellhead to release the blowout.

[0011] The depressurization process for wells with cross-flow includes a rapid depressurization phase, a pressure profile recovery phase, and a normal drainage phase.

[0012] This invention utilizes a series of on-site operations and technical methods, including well flushing of fractured wells, rapid blowout release from fracturing wells, coordinated reduction of bottomhole pressure in the region, and optimization of the drainage system for fractured wells. These methods not only successfully restore gas production in fractured wells but also achieve a significant increase in production, far exceeding the pre-interference rate. This solves the technical problem of the inability to restore fractured wells and addresses traditional perceptions, saving on engineering and equipment investment required for secondary modification of fractured wells and achieving better economic, environmental, and social benefits. The method is simple, easy to operate, and has wide applicability in the industry. This invention changes the traditional concepts and understanding of shale gas and coalbed methane wells, effectively avoiding the difficulty or even inability to restore gas production in fractured wells affected by fracturing interference from adjacent wells.

[0013] Preferably, in step S1, the process of washing the well to prevent channeling includes:

[0014] Before the operation, all components in the well were removed.

[0015] Run tubing into the casing of the wellbore of the well that is being pressured and channeled, and run the tubing into the horizontal section inside the wellbore;

[0016] The circulating fluid is pumped into the annular space between the tubing and the casing, and then drawn in from the top of the tubing.

[0017] Preferably, the inner diameter of the tubing is 40%-60% of the inner diameter of the casing; the circulating fluid is water produced by the well as the medium.

[0018] Preferably, in step S2, the process of venting the blowout from the fractured well includes:

[0019] Open the needle valve at the wellhead of the fractured well to release the fluid. The initial release volume should be 30-40 m³. 3 / d, observe the wellhead pressure drop, the daily wellhead pressure drop is 0.1MPa / d-0.2MPa / d;

[0020] Gradually increase the opening of the needle valve to increase the daily fluid release volume and ensure that the daily pressure drop at the wellhead is 0.2MPa / d-0.3MPa / d.

[0021] Preferred, rapid depressurization stage: Before the bottom-hole flowing pressure reaches the bottom-hole flowing pressure at the moment of initial desorption and casing exposure, the drainage pump operates at Smax to accelerate the drainage and depressurization rate and achieve rapid depressurization; the average daily pressure reduction during the rapid depressurization period is 0.05-0.07 MPa / d.

[0022] Preferred, S max The speed is 150-250 R / min.

[0023] Preferably, the pressure profile recovery stage refers to the stage from the bottom hole pressure at the moment of initial desorption and casing exposure to the bottom hole pressure when gas production ceases due to disturbance. The drainage pump operates at a speed of S... mid run.

[0024] Preferred, S mid The speed is 80-120 R / min.

[0025] Preferred method, during normal drainage and production stage: when gas production stops due to disturbance, the bottom hole flowing pressure reaches the stage of secondary desorption and casing. First, gradually reduce the operating speed of the drainage pump, observe the daily decrease in flow pressure and return fluid, and adjust the operating speed of the pump according to the actual fluid production and flow pressure decrease. The overall daily decrease in flow pressure is 0.02-0.04 MPa / d.

[0026] Preferably, after the normal production stage is completed, the production increase stage begins.

[0027] The advantages of this invention are:

[0028] This invention utilizes a series of field operations and technical means, including well flushing of fractured wells, rapid release of gas from fractured wells, coordinated reduction of bottom hole pressure in the region, and optimization of the drainage system for fractured wells. These methods not only enable fractured wells to successfully resume gas production, but also achieve a significant increase in gas production after recovery, far exceeding the pre-interference production rate. This solves the technical problem of the inability to restore fractured wells and addresses traditional understanding, saving on engineering and equipment investment required for secondary modification of fractured wells, and yielding better economic, environmental, and social benefits. The method is simple, easy to operate, and has wide applicability in this industry.

[0029] This invention changes the traditional concepts and understanding of shale gas and coalbed methane wells, effectively avoiding the situation where wells affected by fracturing interference from adjacent wells are difficult to recover or even unable to resume gas production. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure for washing a well subjected to pressure channeling according to an embodiment of the present invention;

[0031] Figure 2 This is a blowout curve diagram of a fracturing well according to an embodiment of the present invention.

[0032] Figure 3This is a production curve diagram of the three stages of flow pressure recovery in a pressure-controlled well according to an embodiment of the present invention;

[0033] Figure 4 This is a curve diagram of the step-by-step production increase and stabilization mode after the recovery of the well under pressure channeling according to an embodiment of the present invention;

[0034] Figure 5 This is a comprehensive drainage curve diagram of the well pressure channeling according to an embodiment of the present invention;

[0035] Numbering on the map:

[0036] 1. Oil pipe. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] A method for rapidly restoring gas production from fracturing interference in surface gas control wells includes the following steps:

[0039] like Figure 1 As shown, step S1: Cleaning the well for the pressure channeling well; mainly to remove solid deposits such as quartz sand and coal powder in the horizontal section of the wellbore and restore the normal flow channel of the horizontal section.

[0040] Specifically, before the operation, all components in the wellbore, including the pump, tubing, and sucker rod, are removed so that the well cleaning equipment can be lowered into the well for operation; the well cleaning equipment includes the pump, tubing, etc.

[0041] The inner diameter of tubing 1 is 40%-60% of the inner diameter of the casing; typically, the diameter of the production casing in a coalbed methane well is 139.7 mm, and the diameter of the tubing is 73 mm.

[0042] During well flushing operations, water is needed as a medium to transport deposited solid materials. To prevent complex chemical reactions between downhole water and surface water, which could lead to adverse consequences, this embodiment uses the water produced by the well as a medium.

[0043] The tubing is laid down to the horizontal section, and water is injected into the annulus of the tubing and casing through the surface cementing truck pump. This carries away the solid deposits that have settled on the casing and transports them out of the tubing, thus cleaning up the solid deposits such as fracturing sand, quartz sand, and coal dust in the horizontal section of the wellbore and restoring the normal flow channel in the horizontal section.

[0044] Step S2: Perform blowout treatment on the fractured well and depressurize the fractured well at the same time;

[0045] Strengthening the management of blowout from fractured wells is crucial for achieving synchronized pressure reduction across the region. After fracturing operations are completed, the bottom-hole flowing pressure of the cross-flowing well continues to rise, primarily due to the pressure difference between the fractured and cross-flowing wells. To mitigate the ongoing impact on the cross-flowing wells, the traditional "slow release and slow drainage" blowout pattern for coalbed methane wells under geological conditions has been abandoned. A rapid blowout approach has been adopted to quickly reduce the bottom-hole pressure of the fractured wells, minimizing their continued impact on the cross-flowing wells. Simultaneously, the drainage intensity of the cross-flowing wells is accelerated, ensuring a synchronized reduction in bottom-hole pressure across multiple wells in the region and preventing excessive pressure differentials between wells.

[0046] It should be noted that in this embodiment, the two processes of "blowout treatment of the fractured well" and "pressure reduction treatment of the fractured well" can be carried out simultaneously, or the "blowout treatment of the fractured well" and "pressure reduction treatment of the fractured well" can be carried out simultaneously after a period of time.

[0047] like Figure 2 As shown, the blowout treatment for fractured wells specifically includes:

[0048] (1) Open the needle valve at the wellhead of the fractured well to release the fluid. The initial release volume should be 30-40 m³. 3 / d, observe the wellhead pressure drop. The daily pressure drop should not be less than 0.1MPa / d or more than 0.2MPa / d.

[0049] (2) Gradually increase the opening of the needle valve to increase the daily discharge volume. The main basis for this increase is the wellhead pressure drop, ensuring that the daily wellhead pressure drop is 0.2-0.3 MPa / d.

[0050] Pressure reduction measures were implemented for wells prone to gas leakage, and the single-well drainage system for these wells was optimized to achieve precise drainage. The drainage system for wells prone to gas leakage was also optimized, drainage measures for each stage were revised, and monitoring of drainage parameters for wells prone to gas leakage was strengthened to achieve precise drainage and facilitate the early recovery of gas production.

[0051] like Figure 3 , Figure 4 As shown, the pressure of the fractured well increases and groundwater enters the fractured well due to the influence of the fractured well. Therefore, the pressure of the fractured well needs to be reduced and the water needs to be drained.

[0052] The depressurization process for wells with cross-flow includes a rapid depressurization phase, a pressure profile recovery phase, and a normal drainage phase.

[0053] (1) Rapid pressure reduction stage: Before the bottom pressure reaches the initial desorption and casing penetration pressure, the drainage pump operates at its maximum speed Smax to accelerate the drainage and pressure reduction rate, achieving rapid pressure reduction. During the rapid pressure reduction period, the average daily pressure reduction is approximately 0.06 MPa / d. Smax is preferably 150-250 R / min, and in this implementation case, the operating speed Smax is 200 R / min.

[0054] It should be noted that after a coalbed methane well is put into production, it initially only produces water. As drainage and pressure reduction proceed, when the bottom pressure is lower than the critical desorption pressure, the adsorbed gas on the surface of the coal seam near the wellbore begins to desorb and diffuse into the coal seam fissures and cracks. As the amount of desorbed gas gradually increases, continuous bubbles are formed in the water. The gas breaks through to form a flowing phase and flows from the coal seam fissures into the annular space of the wellbore and casing for production.

[0055] During the coalbed methane drainage process, the bottom hole pressure decreases as drainage proceeds. When the bottom hole pressure drops below the critical desorption pressure of coalbed methane, the methane gas adsorbed in the original reservoir state begins to desorb and be produced, and the wellhead casing pressure starts to read from zero.

[0056] In this embodiment, the rapid pressure reduction stage involves rapidly reducing the bottomhole flowing pressure of the fractured well (i.e., the old well affected by fracturing) until it reaches the bottomhole flowing pressure value corresponding to the first desorption casing pressure (before the disturbance). The initial desorption casing pressure moment refers to the point in time when the casing pressure of the old well becomes numerical; casing pressure occurs when the adsorbed gas in the formation becomes free gas. The wellhead casing pressure can be read directly from a pressure gauge.

[0057] (2) Pressure profile recovery stage: From the bottom hole pressure at the moment of initial desorption and casing exposure to the bottom hole pressure when gas production stops due to disturbance, the drainage pump operates at a medium speed Smid. In this implementation case, the pump operates at Smid = 100R / min to ensure pressure reduction while preventing the formation from expelling powder and sand again.

[0058] (3) Normal drainage stage: When gas production stops due to interference, the bottom flow pressure reaches the stage of secondary desorption and casing. First, gradually reduce the operating speed of the pump and observe the daily decrease in flow pressure and return fluid. Adjust the operating speed of the pump according to the actual fluid production and flow pressure decrease. The overall daily decrease in flow pressure is about 0.03 MPa / d.

[0059] After being disturbed, there has already been an initial desorption process. However, due to pressure disturbance, the dynamic equilibrium of desorption will be disrupted, and another desorption process and equilibrium will need to be reached. Therefore, there will be a secondary desorption process.

[0060] (4) Production Enhancement Stage: After the second casing is encountered, observe the flowback fluid and gas production, formulate a reasonable drainage system, and achieve a continuous, stable, and long-term drainage plan. At this time, the well has recovered to normal drainage, and a reasonable drainage system can be formulated based on the existing optimized drainage plan.

[0061] This embodiment overcomes the problems of low resource recovery rates caused by traditional hydraulic fracturing operations, such as the inability of new wells in old well areas to produce normally, blockage of horizontal wellbores, and inability to restore production to pre-interference levels or even cease production altogether. These problems arise from the interaction between new and adjacent wells during fracturing in old well areas. This embodiment addresses these issues through a series of on-site operations and technical means, including well flushing, rapid release of gas from fracturing wells, coordinated reduction of bottomhole pressure in the region, and optimization of the well drainage system. These methods not only successfully restore gas production in fracturing wells but also significantly increase production beyond the pre-interference levels. This solves the technical challenge of restoring fracturing wells and overcomes traditional misconceptions, saving on engineering and equipment investment required for secondary fracturing of such wells and achieving better economic, environmental, and social benefits. The method is simple, easy to operate, and widely applicable in the industry. This embodiment changes the traditional concepts and understanding of shale gas and coalbed methane wells, effectively preventing the difficulty or even inability to restore production in fracturing wells affected by fracturing interference from adjacent wells.

[0062] This embodiment has been successfully applied in four L-shaped horizontal wells (L1 to L4) in Mine Area A that were affected by fracturing interference. It effectively solved the problem of no gas production caused by fracturing interference from adjacent wells, and gas production has now been restored in all four wells, with a cumulative restored gas production of 2.7566 million m³. 3 Well L4 ( Figure 5 (This is the integrated production and drainage curve before and after fracturing in this case study.) The highest daily gas production of a single well before being affected was 4030 m³ / h. 3 / d, after adopting this embodiment, the highest daily gas production of a single well has reached 7701m³. 3 / d, far exceeding the highest daily gas production before the disturbance, showing a significant recovery effect.

[0063] The technology in this embodiment lies in the construction of a method for rapidly restoring gas production and drainage in coalbed methane wells affected by fracturing of adjacent wells. This method significantly reduces the negative impact of fracturing on wells affected by fracturing, better minimizing the degree and duration of interference, and enabling successful gas production recovery. From a direct economic perspective, based on a gas price of 1.88 yuan / m³... 3 According to calculations, the direct economic income from gas production after restoration has reached more than 5 million yuan. In terms of other benefits, this embodiment not only solves the technical problem and traditional understanding that wells with cross-flow cannot be restored, but also has great significance for improving the level of coalbed methane resource development and utilization in coal mining areas, reducing greenhouse gas emissions, preventing coal mine gas disasters, and ensuring normal mine production.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for rapidly restoring gas production after fracturing interference in surface gas control wells, characterized in that, Includes the following steps Step S1: Wash the well to prevent channeling; Step S2: Perform blowout treatment on the fractured well and depressurize the fractured well at the same time; The process of releasing the blowout from a fractured well involves gradually opening the valve at the wellhead to release the blowout. The depressurization process for wells with cross-flow includes a rapid depressurization phase, a pressure profile recovery phase, and a normal drainage phase. Rapid depressurization phase: Before the bottom hole pressure reaches the bottom hole pressure at the moment of initial desorption and casing penetration, the drainage pump operates at a speed of S... max The system operates to accelerate the drainage pressure reduction rate and achieve rapid pressure reduction; during the rapid pressure reduction period, the average daily pressure drop is 0.05-0.07 MPa / d. Pressure profile recovery stage: This stage involves the bottom hole pressure recovering from its initial desorption and casing exposure to its current level when production ceases due to disturbance. The drainage pump operates at a speed of S... mid run; Normal drainage and production stage: When gas production stops due to disturbance, the bottom hole pressure reaches the secondary desorption stage. First, gradually reduce the operating speed of the drainage pump and observe the daily decrease in flow pressure and return fluid. Based on the actual fluid production and flow pressure decrease, adjust the operating speed of the pump. The overall daily decrease in flow pressure is 0.02-0.04 MPa / d.

2. The method for rapid recovery of gas production from fracturing interference in a surface gas control well according to claim 1, characterized in that, In step S1, the process of washing the well to prevent channeling includes: Before the operation, all components in the well were removed. Run tubing into the casing of the wellbore of the well that is being pressured and channeled, and run the tubing into the horizontal section inside the wellbore; The circulating fluid is pumped into the annular space between the tubing and the casing, and then drawn in from the top of the tubing.

3. The method for rapid recovery of gas production from fracturing interference in a surface gas control well according to claim 2, characterized in that, The inner diameter of the tubing is 40%-60% of the inner diameter of the casing; the circulating fluid is water produced by this well as the medium.

4. The method for rapid recovery of gas production from fracturing interference in a surface gas control well according to claim 1, characterized in that, In step S2, the process of venting the blowout from the fractured well includes: Open the needle valve at the wellhead of the fractured well to release the fluid. The initial release volume should be 30-40 m³. 3 / d, observe the wellhead pressure drop, the daily wellhead pressure drop is 0.1MPa / d-0.2MPa / d; Gradually increase the opening of the needle valve to increase the daily fluid release volume and ensure that the daily pressure drop at the wellhead is 0.2MPa / d-0.3MPa / d.

5. The method for rapid recovery of gas production from fracturing interference in a surface gas control well according to claim 1, characterized in that, S max The speed is 150-250 R / min.

6. The method for rapid recovery of gas production from fracturing interference in a surface gas control well according to claim 1, characterized in that, S mid The speed is 80-120 R / min.

7. The method for rapid recovery of gas production from fracturing interference in a surface gas control well according to claim 1, characterized in that, After the normal production phase ends, the production increase phase begins.

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