Method and system for shale gas horizontal well fine fracturing reconstruction and channeling inhibition

Abstract

The application provides a shale gas horizontal well fine fracturing reconstruction channeling inhibition method and system, and relates to the oil and gas collection technical field.A shale gas horizontal well fine fracturing reconstruction channeling inhibition method is applied to a pre-designed and under-construction shale gas horizontal well segmented multi-cluster hydraulic fracturing scheme, and comprises the following steps: real-time tracking and adjustment of fracturing reconstruction construction parameters; real-time monitoring of whether channeling phenomenon appears in the current fracturing reconstruction process; if the channeling phenomenon appears, it is judged whether the current fracturing reconstruction has entered the temporary plugging stage; if the temporary plugging stage is entered, the pump stopping and steering technology and / or high-concentration sand plug technology are adopted according to the channeling phenomenon severity; if the temporary plugging stage is not entered, the relative fracturing scheme enters the temporary plugging stage in advance, and then the pump stopping and steering technology and / or high-concentration sand plug technology are adopted according to the channeling phenomenon severity.

Description

Technical Field

[0001] This application relates to the field of oil and gas extraction technology, and in particular to a method and system for fine fracturing and suppression of hydraulic channeling in shale gas horizontal wells. Background Technology

[0002] Shale gas reservoirs are characterized by tight lithology, low porosity, and extremely low permeability. Effective development of shale gas reservoirs necessitates reservoir stimulation. Currently, the main method for shale gas reservoir stimulation is horizontal well segmented multi-cluster hydraulic fracturing. However, this method often results in inter-well hydraulic channeling, which can easily affect the fracturing or production of adjacent wells. In severe cases, it can lead to decreased production or water flooding of adjacent wells, and even loss of sections in newly fractured adjacent wells, causing significant losses.

[0003] Existing technologies for preventing cross-contamination during horizontal well fracturing mainly involve using mathematical models and other methods to predict the horizontal well's connectivity before fracturing, thereby simulating the probability of cross-contamination risk. This allows for appropriate optimization designs to be implemented in the early stages of fracturing scheme design to minimize the occurrence of cross-contamination.

[0004] However, this technology often encounters discrepancies between actual fracturing operations and predictions, and it cannot effectively control or mitigate unexpected hydraulic cross-flow phenomena. Therefore, how to effectively avoid or suppress hydraulic cross-flow phenomena, whether they have occurred or not, during fine fracturing stimulation of shale gas horizontal wells is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] The purpose of this application is to provide a method and system for suppressing pressure channeling during fine fracturing of shale gas horizontal wells, which can effectively avoid or suppress pressure channeling phenomena that have not occurred or have occurred during the fine fracturing process of shale gas horizontal wells.

[0006] To address the aforementioned technical problems, this application provides the following technical solutions:

[0007] The first aspect of this application provides a method for fine fracturing and pressure channeling suppression in shale gas horizontal wells. This method is applied to a pre-designed and ongoing multi-cluster hydraulic fracturing scheme for shale gas horizontal wells, and includes the following steps: real-time tracking and adjustment of fracturing construction parameters; real-time monitoring of whether pressure channeling occurs during the current fracturing process; if pressure channeling occurs, determining whether the current fracturing has entered the temporary plugging stage; if it has entered the temporary plugging stage, adopting pump stoppage and diversion technology and / or high-concentration sand plugging technology according to the severity of the pressure channeling; if it has not entered the temporary plugging stage, entering the temporary plugging stage earlier than the fracturing scheme, and adopting pump stoppage and diversion technology and / or high-concentration sand plugging technology according to the severity of the pressure channeling.

[0008] In some modified embodiments of the first aspect of this application, the method for fine fracturing and suppression of cross-flow in shale gas horizontal wells further includes the following steps: determining whether the cross-flow phenomenon extends to the subsequent section of the current well or adjacent wells; if the cross-flow phenomenon does not extend to the subsequent section of the current well or adjacent wells, then a stepped displacement increase technique is adopted.

[0009] In some modified embodiments of the first aspect of this application, the method for fine fracturing and suppression of hydraulic channeling in shale gas horizontal wells further includes the following steps: determining whether the hydraulic channeling phenomenon extends to the subsequent section of the current well or an adjacent well; if the hydraulic channeling phenomenon has extended to the subsequent section of the current well or an adjacent well, then adjusting the strength of the fracturing fluid.

[0010] In some modified embodiments of the first aspect of this application, the pump shutdown and reversal technique includes: immediately shutting down the fracturing pump to suppress the extension of the dominant propagation cluster that causes pressure channeling; and restarting the fracturing pump after the dominant propagation cluster has stopped extending to slow down or stop the extension of the dominant propagation cluster.

[0011] In some modified embodiments of the first aspect of this application, the pump shutdown time of the fracturing pump in the pump shutdown and diversion technology is 30 to 60 minutes.

[0012] In some modified embodiments of the first aspect of this application, the high-concentration sand plugging technology includes: increasing the concentration of the mortar used as a proppant, and using a high-concentration mortar with a concentration higher than that designed for the fracturing scheme as a temporary plugging agent to temporarily plug the fractures in order to suppress the pressure channeling phenomenon.

[0013] In some modified embodiments of the first aspect of this application, the stepped displacement technology includes: setting the displacement of fracturing fluid from low to high as a stepped displacement, and slowly increasing the displacement of fracturing fluid to the design displacement of the fracturing scheme according to the stepped displacement during fracturing stimulation.

[0014] In some modified embodiments of the first aspect of this application, adjusting the fracturing fluid strength includes: determining the scale of the hydraulic fracture under the current fracturing fluid usage scale through appropriate simulation or monitoring methods, and appropriately adjusting the fracturing fluid strength according to the scale of the hydraulic fracture.

[0015] In some modified embodiments of the first aspect of this application, the corresponding simulation or monitoring means include: establishing a mathematical model of the relationship between the construction parameters of fracturing and the length of the hydraulic fracture, and monitoring the mathematical model under the condition of changing the strength parameters of the fracturing fluid, until the strength parameters of the fracturing fluid that are suitable for the current construction conditions are adjusted.

[0016] The second aspect of this application provides a fine fracturing and cross-flow suppression system for shale gas horizontal wells, which is established based on any of the fine fracturing and cross-flow suppression methods for shale gas horizontal wells provided in the first aspect of this application.

[0017] Compared to existing technologies, the shale gas horizontal well precision fracturing and pressure channeling suppression method provided in this application is based on the construction of a pre-designed segmented multi-cluster hydraulic fracturing scheme for shale gas horizontal wells. Firstly, it tracks, analyzes, and adjusts the construction parameters of the current well fracturing in real time, and monitors in real time whether pressure channeling occurs during the fracturing process to effectively avoid potential channeling. If pressure channeling has already occurred in the fracturing section of the current well, it first determines whether the current construction stage has entered the temporary plugging stage. If the current construction stage has not yet entered the temporary plugging stage, the pre-designed fracturing scheme is prioritized to bring the fracturing construction into the temporary plugging stage in advance, temporarily plugging the fractures caused by the current well's pressure channeling. If the pressure channeling in the current well still cannot be effectively suppressed after the fractures have been temporarily plugged or the temporary plugging stage has been entered in advance, the pump stoppage and diversion technology and / or high-concentration sand plug technology are used to further suppress the spread of fractures, depending on the severity of the fractures caused by the current well's pressure channeling. The shale gas horizontal well precision fracturing and pressure channeling suppression method provided in this application can, based on the construction of a pre-designed multi-cluster hydraulic fracturing scheme for shale gas horizontal wells, promptly detect and capture potential pressure channeling phenomena during the fracturing process through real-time tracking and analysis, thereby effectively avoiding pressure channeling. If pressure channeling has already occurred during the fracturing process of the current well, it can be effectively suppressed by adopting techniques such as early temporary plugging, pump shutdown and diversion, or high-concentration sand plugging, depending on the current stage of fracturing. This prevents the fractures caused by pressure channeling from extending from the current well to adjacent wells, thus affecting the production operations of adjacent wells. Attached Figure Description

[0018] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this application are illustrated by way of example and not limitation, with the same or corresponding reference numerals denoteing the same or corresponding parts, wherein:

[0019] Figure 1 A schematic diagram of the technical route for the fine fracturing and stress channeling suppression method for shale gas horizontal wells proposed in Embodiment 1 of the present invention is shown. Detailed Implementation

[0020] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0021] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application pertains.

[0022] Example 1

[0023] Reference Appendix Figure 1 Embodiment 1 of the present invention proposes a method for suppressing hydraulic channeling in shale gas horizontal wells through refined fracturing. This method is applied to a pre-designed and under-construction multi-cluster hydraulic fracturing scheme for shale gas horizontal wells and includes the following steps: real-time tracking and adjustment of fracturing construction parameters; real-time monitoring of whether hydraulic channeling occurs during the current fracturing process; if hydraulic channeling occurs, determining whether the current fracturing has entered the temporary plugging stage; if it has entered the temporary plugging stage, adopting pump stoppage and diversion technology and / or high-concentration sand plugging technology according to the severity of the hydraulic channeling; if it has not entered the temporary plugging stage, entering the temporary plugging stage earlier than the fracturing scheme, and adopting pump stoppage and diversion technology and / or high-concentration sand plugging technology according to the severity of the hydraulic channeling.

[0024] Specifically, the shale gas horizontal well fine fracturing and pressure channeling suppression method proposed in Embodiment 1 of the present invention is based on the construction of a pre-designed shale gas horizontal well segmented multi-cluster hydraulic fracturing scheme. Firstly, the construction parameters of the current well fracturing are tracked, analyzed, and adjusted in real time, and the occurrence of pressure channeling during the fracturing process is monitored in real time to effectively avoid pressure channeling that has not yet occurred. If pressure channeling has already occurred in the construction segment of the current well fracturing, it is first determined whether the current construction stage has entered the temporary plugging stage. If the current construction stage has not yet entered the temporary plugging stage, the pre-designed fracturing scheme is prioritized to bring the fracturing construction into the temporary plugging stage in advance, temporarily plugging the fractures caused by the pressure channeling in the current well. If the pressure channeling in the current well still cannot be effectively suppressed after the fractures have been temporarily plugged or the temporary plugging stage has been entered in advance, the pump stoppage and diversion technology and / or high-concentration sand plug technology are used to further suppress the spread of fractures, depending on the severity of the fractures caused by the pressure channeling in the current well.

[0025] As listed above, the shale gas horizontal well fine fracturing and pressure channeling suppression method proposed in Embodiment 1 of the present invention can, based on the construction of a pre-designed multi-cluster hydraulic fracturing scheme for shale gas horizontal wells, promptly detect and capture potential pressure channeling phenomena during the fracturing and fracturing process through real-time tracking and analysis of the fracturing and fracturing construction process, thereby effectively avoiding pressure channeling phenomena. If pressure channeling phenomena have already occurred during the fracturing and fracturing construction of the current well, the pressure channeling phenomena occurring in the current well can be effectively suppressed by adopting techniques such as early temporary plugging, pump shutdown and diversion, or high-concentration sand plugging, according to the current fracturing and fracturing construction stage, thereby preventing the fractures caused by pressure channeling phenomena from extending from the current well to adjacent wells and affecting the production operations of adjacent wells.

[0026] In some embodiments of Embodiment 1 of the present invention, refer to the appendix. Figure 1 The method for suppressing pressure channeling in shale gas horizontal wells through fine fracturing proposed in Embodiment 1 of the present invention further includes the following steps in its implementation: determining whether the pressure channeling phenomenon extends to the subsequent section of the current well or adjacent wells; if the pressure channeling phenomenon does not extend to the subsequent section of the current well or adjacent wells, then a step-by-step increase in discharge rate is adopted.

[0027] Specifically, after a fracturing process occurs in the current well section, in order to prevent the fractures caused by the fracturing process from extending to the subsequent sections of the current well or adjacent wells, the technical solution adopted in this invention also needs to determine whether the fractures caused by the fracturing process in the current well section have extended to the subsequent sections of the current well or adjacent wells. If the fractures caused by the fracturing process have not yet extended to the subsequent sections of the current well or adjacent wells, a stepped displacement technique can be used to prevent the fractures caused by the fracturing process from extending to the subsequent sections of the current well or adjacent wells.

[0028] In some embodiments of Embodiment 1 of the present invention, refer to the appendix. Figure 1 The method for suppressing hydraulic channeling in fine fracturing of shale gas horizontal wells proposed in Embodiment 1 of the present invention further includes the following steps in its implementation: determining whether the hydraulic channeling phenomenon extends to the subsequent section of the current well or an adjacent well; if the hydraulic channeling phenomenon has extended to the subsequent section of the current well or an adjacent well, then adjusting the intensity of the fracturing fluid.

[0029] Specifically, if a fracturing phenomenon occurs in the fracturing section of a well, and it is found that the fractures caused by the fracturing phenomenon have extended to the subsequent section of the well or an adjacent well, in order to prevent the fractures caused by the fracturing phenomenon from continuing to extend to the subsequent section of the well, the technical solution adopted in this invention can be to control the length of the fractures caused by the fracturing phenomenon by adjusting the strength of the fracturing fluid, thereby preventing the fractures from continuing to extend to the subsequent section of the well.

[0030] In some embodiments of the first embodiment of the present invention, the method for suppressing pressure channeling in fine fracturing of shale gas horizontal wells proposed in the first embodiment of the present invention includes the following pump shutdown and reversal techniques: immediately shutting down the fracturing pump to suppress the extension of the dominant expansion cluster that causes pressure channeling; and restarting the fracturing pump after the dominant expansion cluster stops extending to slow down or stop the extension of the dominant expansion cluster.

[0031] Specifically, in order to suppress the pressure channeling phenomenon occurring in the current well, the technical solution adopted in this invention is as follows: if the pressure channeling phenomenon caused by the fracturing of the current well is found to be relatively serious, the fracturing pump can be shut down first, thereby suppressing the extension of the dominant propagation cluster that causes the pressure channeling phenomenon and preventing the dominant propagation cluster from continuing to extend and causing the fracture to spread. After the extension of the dominant propagation cluster stops, the fracturing pump can be restarted. After the fracturing pump is shut down and restarted, the inlet cluster of fracturing fluid will change, which can slow down or stop the extension of the dominant propagation cluster, so as to effectively suppress the pressure channeling phenomenon occurring in the current well and prevent the fracture caused by the fracturing phenomenon from spreading further.

[0032] In some embodiments of the first embodiment of the present invention, the method for fine fracturing and suppression of hydraulic cross-flow in shale gas horizontal wells proposed in the first embodiment of the present invention has a pump shutdown time of 30 to 60 minutes in the pump shutdown and diversion technology.

[0033] Specifically, when using pump shutdown and diversion technology to suppress the dominant expansion cluster of the fracturing pump, the pump shutdown time can be 30 to 60 minutes, which can effectively slow down the extension of the dominant expansion cluster.

[0034] In some embodiments of the first embodiment of the present invention, the method for suppressing pressure channeling in fine fracturing of shale gas horizontal wells proposed in the first embodiment of the present invention includes the high-concentration sand plugging technology: increasing the concentration of the sand slurry used as a proppant, and using high-concentration sand slurry with a concentration higher than that designed in the fracturing scheme as a temporary plugging agent to temporarily plug the fractures in order to suppress pressure channeling.

[0035] Specifically, in order to suppress the pressure channeling phenomenon occurring in the current well, the technical solution adopted in this invention is as follows: if the pressure channeling phenomenon caused by the fracturing of the current well is found to be relatively serious, a high-concentration mortar with a concentration higher than that designed in the fracturing scheme can be used as a temporary plugging agent to temporarily plug the cracks caused by the pressure channeling phenomenon. The mortar used as a proppant is increased in concentration and then used as a temporary plugging agent to temporarily plug the cracks, which can effectively suppress the continued extension of the cracks caused by the pressure channeling phenomenon.

[0036] In some embodiments of the first embodiment of the present invention, the method for fine fracturing and channeling suppression of shale gas horizontal wells proposed in the first embodiment of the present invention includes the following step-by-step increase in discharge rate: setting the discharge rate of fracturing fluid from low to high as a step-by-step discharge rate, and slowly increasing the discharge rate of fracturing fluid to the design discharge rate of the fracturing scheme according to the step-by-step discharge rate during fracturing.

[0037] Specifically, after a fracture channeling phenomenon occurs in the fracturing section of the current well, in order to prevent the fractures caused by the fracture channeling phenomenon from extending to the subsequent sections of the current well or adjacent wells, the technical solution adopted in this invention also needs to determine whether the fractures caused by the fracture channeling phenomenon in the fracturing section of the current well have extended to the subsequent sections of the current well or adjacent wells. If the fractures caused by the fracture channeling phenomenon have not yet extended to the subsequent sections of the current well or adjacent wells, a stepped displacement technology can be adopted. Through this stepped displacement technology, the displacement of fracturing fluid is set as a stepped displacement from low to high, and during fracturing, the displacement of fracturing fluid is slowly increased to the design displacement of the fracturing scheme according to the stepped displacement.

[0038] In some embodiments of the present invention, the method for fine fracturing and suppression of hydraulic fractures in shale gas horizontal wells proposed in the present invention includes adjusting the intensity of the fracturing fluid: determining the scale of the hydraulic fractures under the current scale of fracturing fluid usage through appropriate simulation or monitoring methods, and appropriately adjusting the intensity of the fracturing fluid according to the scale of the hydraulic fractures.

[0039] Specifically, if hydraulic channeling occurs in the fracturing section of a well, and the resulting fractures extend to subsequent sections or adjacent wells, the present invention employs a technical solution to prevent further extension of these fractures. This solution involves using simulation or monitoring methods to determine the scale of the hydraulic fractures at the current fracturing fluid usage level. The fracturing fluid intensity is then adjusted accordingly to control the length of the fractures caused by the hydraulic channeling, preventing further extension and exacerbating the problem. Furthermore, if the hydraulic channeling in the fracturing section is severe, the fracturing scale can be immediately reduced, and the fracturing pump can be shut down prematurely to halt the fracturing operation, thus preventing further extension and more serious consequences.

[0040] In some embodiments of the first embodiment of the present invention, the method for fine fracturing and suppression of hydraulic fractures in shale gas horizontal wells proposed in the first embodiment of the present invention includes the following simulation or monitoring methods: establishing a mathematical model of the relationship between the construction parameters of fracturing and the length of hydraulic fractures, and monitoring the mathematical model under the condition of changing the strength parameters of the fracturing fluid until the strength parameters of the fracturing fluid that are suitable for the current construction conditions are adjusted.

[0041] Specifically, to prevent fractures caused by hydraulic channeling in the current well's construction section from extending to adjacent wells, the technical solution adopted in this invention involves establishing a mathematical model relating the construction parameters of the current well and adjacent wells' fracturing to the length of the hydraulic fractures. This model is then used to adjust the fracturing fluid strength parameters and monitor the model in real time until the appropriate fracturing fluid strength parameters are found that suit the current well's construction conditions. These parameters are then applied to the fracturing of the current well to prevent fractures caused by hydraulic channeling from extending to adjacent wells and affecting their production operations.

[0042] Example 2

[0043] Embodiment 2 of the present invention proposes a fine fracturing and pressure channeling suppression system for shale gas horizontal wells. This fine fracturing and pressure channeling suppression system for shale gas horizontal wells is established based on the fine fracturing and pressure channeling suppression method for shale gas horizontal wells proposed in Embodiment 1 of the present invention.

[0044] It should be noted that in the description of this specification, the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention; the terms "connection," "installation," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present invention can be understood according to the specific circumstances.

[0045] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0046] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for fine fracturing and pressure channeling suppression in shale gas horizontal wells, applied to a pre-designed and under-construction multi-cluster hydraulic fracturing scheme for shale gas horizontal wells, characterized in that, Includes the following steps: Real-time tracking and adjustment of fracturing stimulation construction parameters; Real-time monitoring is conducted to check for any pressure channeling during the current fracturing process. If the aforementioned pressure channeling phenomenon occurs, determine whether the current fracturing modification has entered the temporary plugging stage: If the temporary blockage stage has been reached, pump shutdown and diversion technology and / or high-concentration sand plug technology shall be adopted according to the severity of the pressure surge phenomenon. If the temporary plugging stage is not reached, the temporary plugging stage is reached earlier than the fracturing scheme, and pump stop and diversion technology and / or high-concentration sand plug technology are adopted according to the severity of the pressure channeling phenomenon. Determine whether the pressure channeling phenomenon extends to subsequent sections of the current well or adjacent wells: If the pressure channeling phenomenon does not extend to subsequent sections of the current well or adjacent wells, a stepped displacement increase technique is adopted. If the fracturing phenomenon has extended to subsequent sections of the current well or adjacent wells, adjust the strength of the fracturing fluid.

2. The method for fine fracturing and channeling suppression in shale gas horizontal wells according to claim 1, characterized in that, The pump shutdown and reversal technology includes: Immediately shut down the fracturing pump to suppress the extension of the dominant cluster that is causing the fracturing phenomenon; After the dominant extension cluster stops extending, the fracturing pump is restarted to slow down or stop the extension of the dominant extension cluster.

3. The method for fine fracturing and channeling suppression in shale gas horizontal wells according to claim 2, characterized in that, The pump shutdown and diversion technology described above involves a pump shutdown time of 30 to 60 minutes.

4. The method for fine fracturing and suppression of hydraulic channeling in shale gas horizontal wells according to claim 1, characterized in that, The high-concentration sand plugging technology includes: Increase the concentration of the mortar used as a proppant, and use high-concentration mortar with a concentration higher than that designed in the fracturing scheme as a temporary plugging agent to temporarily plug the cracks in order to suppress the pressure channeling phenomenon.

5. The method for fine fracturing and suppression of hydraulic channeling in shale gas horizontal wells according to claim 1, characterized in that, The stepped emission reduction technology includes: The fracturing fluid discharge rate is set as a stepped discharge rate from low to high, and during the fracturing transformation, the fracturing fluid discharge rate is slowly increased to the design discharge rate of the fracturing scheme according to the stepped discharge rate.

6. The method for fine fracturing and channeling suppression in shale gas horizontal wells according to claim 1, characterized in that, The adjustment of the fracturing fluid strength includes: The scale of the hydraulic fracture under the current fracturing fluid usage is determined by appropriate simulation or monitoring methods, and the fracturing fluid intensity is adjusted appropriately according to the scale of the hydraulic fracture.

7. The method for fine fracturing and channeling suppression in shale gas horizontal wells according to claim 6, characterized in that, The corresponding simulation or monitoring methods include: A mathematical model is established to determine the relationship between the construction parameters of the fracturing modification and the length of the hydraulic fracture. The mathematical model is then monitored under the condition of changing the strength parameters of the fracturing fluid until the strength parameters of the fracturing fluid that are suitable for the current construction conditions are adjusted.

8. A precision fracturing and channeling suppression system for shale gas horizontal wells, characterized in that, This method is based on the fine fracturing and stress channeling suppression method for shale gas horizontal wells as described in any one of claims 1-7.

Images