Fracturing optimization method and system for deep coal rock gas reservoir based on post-compression gas and water production characteristics analysis

Abstract

The present application belongs to the field of petroleum and natural gas engineering, and discloses a deep coal rock gas reservoir fracturing optimization method and system based on post-pressing gas and water production characteristic analysis. The present application uses a water injection algorithm of Petrel software to inject the retained fracturing fluid around the fracture, so as to accurately restore the distribution field of the fracture and the retained fracturing fluid around the wall surface. Then, on the basis, a gas and water production comprehensive evaluation index considering five key parameters is used to evaluate the post-pressing gas and water production characteristics and production capacity, so as to screen out the hydraulic fracturing construction parameter chart with high score. The chart is used to guide the design of the target reservoir fracturing scheme, so as to finally realize the target of improving the EUR of the deep coal rock gas reservoir and improving the post-pressing production effect of the coal rock reservoir single well.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas engineering, specifically relating to an optimized method and system for fracturing deep coal and gas reservoirs based on post-fracturing gas-water production characteristics analysis. Background Technology

[0002] Deep coal-rock gas reservoirs are generally characterized by well-developed cleavage fractures, strong heterogeneity, and low permeability, making it difficult for natural production capacity to meet the demands of industrial-scale development. Hydraulic fracturing technology, by creating artificial fractures and complex fracture networks in coal-rock reservoirs, significantly improves reservoir seepage conditions and is currently one of the key technologies for achieving large-scale and efficient development of deep coal-rock gas reservoirs. It has become an indispensable core process in the development of this type of reservoir.

[0003] However, the volume of hydraulic fracturing fluid in deep coal and rock reservoirs is extremely large, and the flowback rate of fracturing fluid is usually no more than 40%. A large amount of fracturing fluid remains in the pores of the rock around the fracture and its walls, resulting in very complex gas and water production characteristics after fracturing in coal and rock reservoirs. How to optimize the fracturing operation plan to enable rapid fluid drainage and gas production in the formation and improve the final EUR is the main technical challenge currently facing the large-scale hydraulic fracturing development of deep coal and rock gas reservoirs. Summary of the Invention

[0004] To address the technical bottlenecks in large-scale hydraulic fracturing development of deep coalbed methane reservoirs, this invention creatively proposes an optimization method and system for fracturing deep coalbed methane reservoirs based on post-fracturing gas-water production characteristics analysis. This method can accurately simulate and analyze the post-fracturing gas-water production characteristics of deep coalbed methane reservoirs, forming a fracturing optimization design scheme with rapid fluid drainage and improved EUR (Estimated Ultimate Recovery) as the core objectives, thereby improving the post-fracturing production effect of single wells in coalbed methane reservoirs.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: An optimized fracturing method for deep coal-rock gas reservoirs based on post-fracturing gas-water production characteristics analysis includes the following steps: S1. Using the reservoir properties and layered data of the target reservoir, a geological model of the target stratigraphic level, including the roof, floor and coal-rock sections, is established based on the three-dimensional geological modeling module of Petrel software. S2. Based on the rock mechanics parameters of the target reservoir and the geological model of the target stratum, establish the geomechanical model of the target stratum using the Visage geostress module of Petrel software, and eliminate interlayer unbalanced forces. S3. Using the completion parameters, wellbore trajectory parameters, and the target formation geomechanical model of the fractured well A, establish a target formation geomechanical model including the wellbore. S4. Based on the fracturing parameters of the fractured well A, set the pumping program table in the fracturing module of Petrel software, and then perform hydraulic fracturing simulation on the target layer geomechanical model containing the wellbore established in S3 to obtain the simulation results of hydraulic fracture propagation. S5. The simulation results of hydraulic fracture propagation and the cleavage distribution field of the target layer are corrected using the on-site fracturing construction monitoring curve of the fractured well A. After correction, the three-dimensional hydraulic fracture propagation morphology and the cleavage distribution field of the target layer of the fractured well A are obtained. S6. Using the two-phase flow parameters and the three-dimensional hydraulic fracture propagation morphology and cleavage distribution field of the target layer obtained from the simulation in S5, a post-pressurization production numerical model of the target layer is established in the production module of Petrel software. S7. Based on the fracturing parameters of the fractured well A, set the amount of fracturing fluid to be retained. Then, based on the post-fracturing production numerical model of the target formation, use the Petrel software water injection algorithm to inject the amount of retained fracturing fluid into the reservoir through the hydraulic fracture to simulate the distribution field of the retained fracturing fluid in the hydraulic fracture and around the reservoir. S8. Based on S7, use the target formation post-fracturing production numerical model to set the production regime and simulate the daily gas and water production of the fractured well A. S9. The production regime is corrected by using the daily water and gas production data monitored in the field of the fractured well A to obtain the corrected production regime. S10. Based on the production system corrected in S9, change the fracturing pump injection procedure and repeat S4, S6, S7, and S8. Monitor the cumulative gas production, stable production time, free gas reduction ratio, adsorbed gas reduction ratio, and liquid discharge efficiency. Use the gas-water production comprehensive evaluation index as the scoring standard to adjust the pump injection procedure and fracturing construction parameters to obtain the fracturing optimization design drawing. S11. Use the fracturing optimization design chart obtained in S10 to guide the fracturing design of adjacent wells in the target reservoir, thereby achieving fracturing optimization of deep coal and gas reservoirs.

[0006] Preferably, the specific process of S2 is as follows: Rock mechanics parameters are input into the geological model of the target stratum, and interpolation correction is performed using the sequential Gaussian simulation method. Then, boundary conditions are applied to the boundary of the geological model of the target stratum, and the grid and boundary conditions are continuously adjusted until the unbalanced force between the top and bottom plates and the coal and rock sections of the target stratum is less than 0.01 MPa.

[0007] Preferably, the rock mechanical parameters include Young's modulus and Poisson's ratio.

[0008] Preferably, the specific process of S5 is as follows: S5.1, Based on the geomechanical model of the target stratum containing the wellbore, randomly distribute the preset parameters of the cleavage; S5.2 Set up the pump injection program to simulate hydraulic fracturing using the fracturing module and monitor the fracturing operation curve; S5.3. Compare the monitored fracturing operation curve with the on-site fracturing operation monitoring curve to obtain the first comparison error; S5.4 If the first comparison error is above the first preset value, then modify the parameters of the cleavage distribution and repeat S5.2 to S5.3. S5.5 When the first comparison error is less than the first preset value, after the correction is completed, the fracture morphology at this time is the true three-dimensional hydraulic fracture propagation morphology of the fractured well A, and the distribution parameters of the cleavage at this time are the cleavage distribution field of the target layer.

[0009] Preferably, the first preset value is 5%; when using the field fracturing construction monitoring curve of the fractured well A to correct the hydraulic fracture propagation simulation results and the cleavage distribution field of the target layer, the correction is completed when the overall error between the daily gas production and daily water production obtained by numerical simulation and the field monitoring data is within 5%.

[0010] Preferably, the parameters of the cleavage distribution include: the cleavage distribution density, the cleavage angle, and the cleavage length.

[0011] Preferably, the specific process of S7 is as follows: S7.1 Calculate the total volume of retained fracturing fluid using the volume of retained fracturing fluid; S7.2 Obtain the average pressure and fracturing fluid viscosity inside the hydraulic fractures in the final corrected target layer geomechanical model in S5; S7.3 Set the injection regime in the Petrel software water injection algorithm, including constant injection pressure, total injection volume and injection fluid viscosity; the constant injection pressure is the average pressure in S7.2, and the injection fluid viscosity is the fracturing fluid viscosity in S7.2; S7.4. Start the Petrel software water injection algorithm to inject liquid into the fracture using the wellbore as the injection port to simulate the retention process of fracturing fluid in the hydraulic fracture network of coal and rock, analyze the water saturation field around the fracture, and then obtain the simulated distribution field of the retained fracturing fluid in the hydraulic fracture and around the reservoir.

[0012] Preferably, in step S7.1, the total volume of retained fracturing fluid is calculated using the following formula: Q=Q 总 ×(1-Ra) in, Q This refers to the amount of fracturing fluid retained. Q 总 The total liquid volume in the pumping procedure table; Ra This represents the fracturing fluid flowback rate.

[0013] Preferably, in step S11, the calculation method and steps for the comprehensive evaluation index of gas and water production are as follows: S11.1 Normalize the cumulative gas production, stable production time, percentage decrease in free gas, percentage decrease in adsorbed gas, and liquid discharge efficiency using the following formula:

[0014] in, X in Represents normalized cumulative gas production, stable production time, decrease ratio of free gas / adsorbed gas, and liquid discharge efficiency; X i Represents the original values ​​of the five key parameters; X i-max , X i-min These are the maximum and minimum values ​​of each key parameter across all experimental cases; The drainage efficiency = Q 1 / Q ,in, Q 1 refers to the total amount of liquid discharged within the first 30 days of post-pressurization production; The ratio of free gas to adsorbed gas decreases = (G) 总 -G 剩余 ) / G 总 Among them, G 总 G represents the total content of free / adsorbed gas in the geological model of the target stratum; 剩余 The total remaining free / adsorbed gas content in the geological model of the target stratum for 10 years of post-pressurization production; S11.2 Calculate the comprehensive gas-water production evaluation index S based on the weights of cumulative gas production, stable production time, percentage decrease in free gas, percentage decrease in adsorbed gas, and liquid discharge efficiency:

[0015] in, X 1n Represents normalized cumulative gas production, X 2n Represents the period of stable production, X 3n Represents drainage efficiency, X 4n Represents the percentage of free gas that decreased. X 5n This represents the percentage decrease in adsorbed gas.

[0016] The present invention also provides a system for implementing the deep coal and rock gas reservoir fracturing optimization method based on post-fracturing gas-water production characteristic analysis described in the present invention, comprising: The first modeling module is used to establish a geological model of the target stratigraphic level, including the roof, floor, and coal-rock sections, based on the reservoir physical property parameters and stratigraphic data of the target reservoir and the three-dimensional geological modeling module of Petrel software. The second modeling module is used to establish a geomechanical model of the target stratum based on the rock mechanical parameters of the target reservoir and the geological model of the target stratum, using the Visage geostress module of Petrel software, and to eliminate interlayer unbalanced forces. The third modeling module is used to establish a target layer geomechanical model including the wellbore using the completion parameters, wellbore trajectory parameters, and the target layer geomechanical model of the fractured well A. The first simulation module is used to set up the pumping procedure table in the fracturing module of Petrel software based on the fracturing parameters of the fractured well A, and then perform hydraulic fracturing simulation based on the geomechanical model of the target stratum containing the wellbore to obtain the simulation results of hydraulic fracture propagation. The first correction module is used to correct the hydraulic fracture propagation simulation results and the cleavage distribution field of the target layer using the on-site fracturing construction monitoring curve of the fractured well A. After correction, the three-dimensional hydraulic fracture propagation morphology and the cleavage distribution field of the target layer of the fractured well A are obtained. The fourth modeling module is used to establish a post-pressurization production numerical model of the target layer in the Petrel software production module using two-phase flow parameters and the simulated three-dimensional hydraulic fracture propagation morphology and cleavage distribution field of the target layer. The second simulation module is used to set the amount of fracturing fluid to be retained based on the fracturing parameters of the fractured well A. Then, based on the post-fracturing production numerical model of the target formation, the Petrel software water injection algorithm is used to inject the amount of retained fracturing fluid into the reservoir through the hydraulic fracture, and to simulate the distribution field of the retained fracturing fluid in the hydraulic fracture and around the reservoir. The third simulation module is used to set the production regime based on the target formation post-fracturing production numerical model, based on the second simulation module, to simulate the daily gas and water production of the fractured well A. The second correction module is used to correct the production regime using the daily water and gas production data monitored on-site in the fractured well A, and to obtain the corrected production regime. The optimization module is used to modify the fracturing pump injection program based on the production system corrected by the second correction module. It reuses the first simulation module, the fourth modeling module, the second simulation module, and the third simulation module for data processing, monitors the cumulative gas production, stable production time, free gas reduction ratio, adsorbed gas reduction ratio, and liquid discharge efficiency, and uses the gas-water production comprehensive evaluation index as the scoring standard to adjust the pump injection program and fracturing construction parameters to obtain the fracturing optimization design drawing. Design Module: Used to guide the fracturing design of adjacent wells in the target reservoir using the fracturing optimization design chart obtained from the optimization module, thereby achieving fracturing optimization of deep coal and gas reservoirs.

[0017] The present invention has the following beneficial effects: This invention presents an optimized fracturing method for deep coal-rock gas reservoirs based on post-fracturing gas-water production characteristic analysis. It addresses the technical challenges of low fracturing fluid flowback rates and complex gas-water production characteristics caused by retained fracturing fluid in deep coal-rock gas reservoirs. Specifically: First, through steps S1-S3, using reservoir properties, layering, and rock mechanics parameters, and employing the 3D geological modeling module and Visage geostress module of Petrel software, a geomechanical model including the roof, floor, coal-rock section, and wellbore is constructed, and interlayer imbalance forces are eliminated, laying the foundation for subsequent simulations. Steps S4-S6 combine the fracturing parameters of the already fractured well A to conduct hydraulic fracturing simulations, and use on-site construction monitoring curves to correct the fracture propagation simulation. The results and cleavage distribution field are used to construct a post-fracturing production numerical model. Step S7 uses the Petrel software water injection algorithm to inject the amount of retained fracturing fluid based on the actual fracturing parameters into the reservoir, accurately restoring the distribution field of the retained fracturing fluid around the fractures and reservoir. Steps S8-S9 simulate gas and water production data by setting production regimes and correcting the production regimes by combining on-site monitoring data to form a closed loop to ensure that the simulation results match the actual production. Steps S10-S11 repeat key simulation steps by changing the pump injection program, monitoring key parameters such as cumulative gas production and fluid discharge efficiency, and using the gas and water production comprehensive evaluation index to screen the optimal parameters and form an optimization chart to guide the fracturing design of adjacent wells. The technical solution of this invention innovatively integrates the multi-module functions of Petrel software with reservoir geological characteristics and post-fracturing gas-water production patterns. Through a complete process of model building, simulation, correction, and optimization, it accurately restores the distribution of retained fracturing fluid, accurately simulates gas-water production characteristics, and achieves scientific optimization of fracturing parameters. This effectively solves the problems of simulation and reality being disconnected and optimization lacking scientific standards in existing technologies, and truly improves the accuracy and effectiveness of fracturing development in deep coal and rock gas reservoirs. Attached Figure Description

[0018] Figure 1 This is a three-dimensional geological model of the eastern part of the basin in the study area, as described in this embodiment of the invention.

[0019] Figure 2 This is a three-dimensional geomechanical model of the eastern part of the basin in the study area, as described in this embodiment of the invention.

[0020] Figure 3 This is a geomechanical model of well Mi124 and its shaft in an embodiment of the present invention.

[0021] Figure 4 The results of hydraulic fracturing fracture propagation simulation in well Mi124 are shown in this embodiment of the invention.

[0022] Figure 5 This is the distribution field of cleavage in the eastern part of the basin in the study area of ​​this invention.

[0023] Figure 6 This is a numerical model of post-pressure production from well Mi124 in an embodiment of the present invention.

[0024] Figure 7 This is the water saturation field around the fracture after pressure treatment in well Mi124 in this embodiment of the invention.

[0025] Figure 8 This is a comparison of the daily gas production and daily water production curve correction results of well Mi124 in this embodiment of the invention.

[0026] Figure 9 The following is a comprehensive evaluation index score of gas and water production under different simulation schemes for well Mi124 in this embodiment of the invention. Detailed Implementation

[0027] The present invention will be further described clearly and in detail below with reference to specific embodiments and the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0028] The principle of the deep coal-rock gas reservoir fracturing optimization method based on post-fracturing gas-water production characteristic analysis is as follows: Since the residual fracturing fluid and fracture network morphology in deep coal-rock gas reservoirs have a significant impact on the post-fracturing production effect of gas wells, this invention patent creatively utilizes the Petrel software water injection algorithm to inject the residual fracturing fluid around the fractures, thereby accurately restoring the distribution field of the residual fracturing fluid around the fractures and their walls. Then, based on this, the post-fracturing gas-water production characteristics and production capacity are evaluated using a comprehensive gas-water production evaluation index that considers five key parameters, thereby selecting high-scoring hydraulic fracturing construction parameter charts. These charts are then used to guide the design of targeted fracturing schemes for the target reservoirs, ultimately achieving the goal of improving the EUR (Effective Energy Recovery) of deep coal-rock gas reservoirs.

[0029] Specifically, the optimization method of the present invention includes the following steps: (1) Collect the rock mechanics parameters, two-phase flow parameters, layer data, reservoir physical property parameters, completion parameters of fractured well A, wellbore trajectory parameters of fractured well A, fracturing parameters of fractured well A, field fracturing construction monitoring curves of fractured well A, and daily water and gas production data of fractured well A monitored in the field; among them, the two-phase flow parameters include the coal and rock isothermal adsorption curves of the target reservoir and the relative permeability curves of gas and liquid two phases.

[0030] (2) Using reservoir physical parameters and layer data, a geological model of the target stratigraphic level including the roof, floor and coal-rock sections was established based on the three-dimensional geological modeling module of Petrel software; (3) Import the rock mechanics parameters into the geological model of the target stratum, establish the geological mechanics model of the target stratum using the Visitation geostress module of Petrel software, and eliminate the unbalanced forces between strata; specifically, first import the rock mechanics parameters (including Young's modulus and Poisson's ratio) into the geological model of the target stratum, and use the sequential Gaussian simulation method for interpolation correction; then apply boundary conditions to the model boundary, and continuously adjust the grid and boundary conditions until the unbalanced forces between the top plate, bottom plate and coal-rock section of the target stratum are less than 0.01 MPa.

[0031] (4) Import the completion parameters and wellbore trajectory parameters of the fractured well A into the target formation geomechanical model to establish a target formation geomechanical model including the wellbore; (5) Based on the fracturing parameters of the fractured well A, set the pumping program table in the fracturing module of the Petrel software, and then perform hydraulic fracturing simulation based on the target stratum geomechanical model containing the wellbore established in step (4); (6) The hydraulic fracture propagation simulation results and the cleavage distribution field of the target layer are corrected using the in-situ fracturing construction monitoring curve of the fractured well A until the overall error between the fracturing construction curve obtained by numerical simulation and the in-situ fracturing construction monitoring curve is within 5%, thereby accurately simulating the three-dimensional hydraulic fracture propagation morphology of the fractured well A and the cleavage distribution field of the target layer. In this step, the key parameters that need to be corrected for the cleavage distribution field include: cleavage distribution density, cleavage angle, and cleavage length. Specifically, the detailed processing procedure of this step is as follows: Step (6.1): First, based on the geomechanical model of the target stratum including the wellbore, randomly distribute the stratigraphic lines with an angle of X° and a density of Y / m. 2 A cleavage with a length of Z cm; Step (6.2): ​​Then set up the pumping program to simulate hydraulic fracturing using the fracturing module and monitor the fracturing construction curve; Step (6.3): Compare the fracturing operation curve monitored by the numerical simulation software with the on-site fracturing operation monitoring curve to obtain the error: Step (6.4): If the comparison error is greater than 5%, then modify the distribution angle, density and length of the cleavage, and repeat steps (6.2) to (6.3). Step (6.5): When the error between the fracturing construction curve monitored by the numerical simulation software and the on-site fracturing construction monitoring curve is less than 5%, the angle, density and length of the cleavage are the distribution field of the cleavage in the target layer after correction, and the fracture morphology at this time is the true three-dimensional hydraulic fracture propagation morphology of the fractured well A.

[0032] (7) Import the two-phase flow parameters and the three-dimensional crack propagation simulation results obtained in step (6) into the Petrel software production module to establish a numerical model for post-pressure production of the target layer. (8) Set the amount of fracturing fluid to be retained based on the fracturing parameters of the fractured well A. Q Then, based on the target formation post-fracturing production numerical model, the Petrel software water injection algorithm is used to determine the amount of retained fracturing fluid. Q The fracturing fluid is injected into the reservoir through hydraulic fractures to accurately simulate the distribution field of retained fracturing fluid in and around the hydraulic fractures and reservoir; the specific steps are as follows: Step (8.1): First, calculate the total volume of retained fracturing fluid using the formula; specifically, the volume of retained fracturing fluid... Q The calculation method is as follows: Q=Q 总 ×(1-Ra) in, Q 总 The total liquid volume in the pumping procedure table; Ra This represents the fracturing fluid flowback rate.

[0033] Step (8.2): Check the average pressure P1 inside the hydraulic fracture in the final corrected model from step (6), and the viscosity of the fracturing fluid. μ ; Step (8.3): Set the injection regime in the Petrel water injection algorithm: constant injection pressure P1 (i.e., using the average pressure P1 in step (8.2) as the constant injection pressure), total injection volume Q The viscosity of the injected liquid μ (That is, the viscosity of the fracturing fluid in step (8.2) is used as the viscosity of the injected fluid); Step (8.4): Start the algorithm by injecting liquid into the fracture using the wellbore as the injection port to simulate the retention process of fracturing fluid in the hydraulic fracture network of coal and rock, and analyze the water saturation field around the fracture.

[0034] (9) Based on step (8), the production system is set using the target formation post-fracturing production numerical model to simulate the daily gas and water production of the fractured well A; (10) Use the daily water and gas production data monitored in the field of the fractured well A to correct the production system until the overall error between the daily gas and water production obtained by numerical simulation and the field monitoring data is within 5%. (11) Based on the production system obtained in step (10), change the fracturing pump injection program, and repeat steps (5), (7), (8), and (9) for data processing. Monitor five key parameters: cumulative gas production, stable production time, free gas reduction ratio, adsorbed gas reduction ratio, and liquid discharge efficiency. Using the gas-water production comprehensive evaluation index as the scoring standard, continuously adjust the pump injection program and fracturing construction parameters until a fracturing optimization design drawing with a score greater than 0.98 is obtained. The calculation method and steps of the gas-water production comprehensive evaluation index are as follows: Step (11.1): Normalize the five key parameters: cumulative gas production, stable production time, percentage decrease in free gas, percentage decrease in adsorbed gas, and liquid discharge efficiency.

[0035] in, X in Represents normalized cumulative gas production, stable production time, decrease ratio of free gas / adsorbed gas, and liquid discharge efficiency; X i Represents the original values ​​of the five key parameters; X i-max , X i-min This represents the maximum and minimum values ​​of each key parameter across all experimental cases.

[0036] Step (11.2): Calculate the comprehensive evaluation index S of gas and water production according to the weights of the five key parameters:

[0037] in, X 1n Represents normalized cumulative gas production, X 2n Represents the period of stable production, X 3n Represents drainage efficiency, X 4n Represents the percentage of free gas that decreased. X 5n This represents the percentage decrease in adsorbed gas.

[0038] The drainage efficiency = Q 1 / Q ,in, Q 1 refers to the total amount of liquid discharged within the first 30 days of post-pressurization production; Free gas / adsorbed gas drop ratio = (G 总 -G 剩余 ) / G 总 Among them, G 总 G represents the total content of free / adsorbed gas in the geological model of the target stratum;剩余 This represents the total remaining free / adsorbed gas content in the geological model of the target stratum for 10 years of post-pressurization production.

[0039] (12) Use the fracturing optimization design chart obtained in step (11) to guide the fracturing design of adjacent wells in the target reservoir.

[0040] Example 1 The eastern part of a certain basin has abundant coal-rock gas reserves, with coal seams generally exceeding 2000m in depth. Currently, development mainly relies on large-scale hydraulic fracturing technology. However, field fracturing results show insufficient fracture network modification, complex post-fracturing gas-water production characteristics, and a rapid decline in production capacity. Therefore, the fracturing scheme for well Mi124 was optimized using the above-mentioned method of this invention. The specific steps are as follows: (1) Rock mechanics parameters, two-phase flow parameters, layer data, reservoir physical property parameters, completion parameters of well Mi124, wellbore trajectory parameters of well Mi124, fracturing parameters of well Mi124, field fracturing construction monitoring curve of well Mi124, and daily water and gas production data of well Mi124 were collected in the eastern part of the basin in the study area. (2) Using reservoir physical property parameters and layered data, a three-dimensional geological modeling system was established based on the Petrel software's three-dimensional geological modeling module, as follows: Figure 1 The geological model shown includes the target stratigraphic section, including the roof, floor, and coal-rock sections. (3) The rock mechanical parameters of well Mi124 were imported into the geological model of the target stratum, and the in-situ stress model was established using the Visitage module of Petrel software. Figure 2 The target stratum geomechanical model is shown, and inter-stratum unbalanced forces are eliminated; (4) The completion parameters and wellbore trajectory parameters of well Mi124 were imported into the target stratum geomechanical model to establish the following: Figure 3 The wellbore of the Mi 124 well shown; (5) Based on the fracturing parameters of well Mi124, the pumping program table was set in the fracturing module of Petrel software, and then hydraulic fracturing simulation was carried out on the basis of the model established in step 4. (6) The simulation results of hydraulic fracture propagation and the cleavage distribution field of the target layer were corrected using the field fracturing construction monitoring curve of well Mi124 until the overall error between the fracturing construction curve obtained by numerical simulation and the field fracturing construction monitoring curve was within 5%, thus accurately simulating the three-dimensional hydraulic fracture propagation morphology of well Mi124 (e.g., Figure 4 (as shown) and the cleavage distribution field of the target layer (such as Figure 5 (as shown) (7) The two-phase flow parameters and the three-dimensional crack propagation simulation results obtained in step 6 were imported into the post-compression production module of Petrel software to establish a system. Figure 6 The numerical model of post-pressure production of well Mi124 is shown below; (8) Based on the fracturing parameters of well Mi124, the retained fracturing fluid volume was set to 9000 m³. 3 Then, based on the target stratum pressure post-production numerical model, the Petrel software water injection algorithm was used to inject water into the 9000m stratum. 3 Retained fracturing fluid was injected into the reservoir through the hydraulic fracture at a pressure of 15 MPa and a viscosity of 30 mPa·s. The water saturation field of the retained fracturing fluid in the hydraulic fracture and around the reservoir was accurately simulated. The simulation results are as follows: Figure 7 As shown; (9) Based on step 8, the production system is set using the numerical simulation model of post-pressure production of well Mi124 to simulate the daily gas and water production of well Mi124. (10) The production regime was corrected using the daily water and gas production data from the field monitoring of well Mi124 until the overall error between the daily gas and water production obtained from the numerical simulation and the field monitoring data was within 5%. The correction results are as follows: Figure 8 As shown, the production regime was determined to be a bottom hole flowing pressure of 23 MPa at this point; (11) Based on the production system obtained in step (10), the fracturing pump injection program was changed, and steps (5), (7), (8), and (9) were repeated. Five key parameters were monitored: cumulative gas production, stable production time, percentage decrease of free gas, percentage decrease of adsorbed gas, and drainage efficiency. The pump injection program and fracturing construction parameters were adjusted 16 times using the gas-water production comprehensive evaluation index as the core scoring standard (the scores are as follows). Figure 9 As shown in Table 1), the final fracturing optimization design board with a score of 1 was obtained (Scheme 4 is shown in Table 1).

[0041] Table 1

[0042] (12) The fracturing optimization design board obtained in step (11) guided the fracturing design of well Mi125J. The final daily gas production after fracturing was increased by 15% compared with other wells, and the overall optimization effect was significant.

[0043] As can be seen from the above results, the present invention has the following characteristics: (1) The technical solution of the present invention can be used to truly restore the distribution field of the fracture and the fracturing fluid retained around the wall of the deep coal and rock gas reservoir after fracturing; (2) The technical solution of the present invention can be used to accurately simulate the distribution curve of gas and water production after fracturing in the deep coal and rock gas reservoir; (3) The technical solution of the present invention can be used to evaluate the characteristics and production capacity of gas and water production after fracturing, and select the optimal fracturing construction parameter chart with the best production effect and the strongest drainage capacity.

[0044] Furthermore, embodiments of the present invention also provide a fracturing optimization system for deep coal and gas reservoirs based on post-compression gas-water production characteristic analysis, used to implement the deep coal and gas reservoir fracturing optimization method based on post-compression gas-water production characteristic analysis described above. The system includes: The first modeling module is used to establish a geological model of the target stratigraphic level, including the roof, floor, and coal-rock sections, based on the reservoir physical property parameters and stratigraphic data of the target reservoir and the three-dimensional geological modeling module of Petrel software. The second modeling module is used to establish a geomechanical model of the target stratum based on the rock mechanical parameters of the target reservoir and the geological model of the target stratum, using the Visage geostress module of Petrel software, and to eliminate interlayer unbalanced forces. The third modeling module is used to establish a target layer geomechanical model including the wellbore using the completion parameters, wellbore trajectory parameters, and the target layer geomechanical model of the fractured well A. The first simulation module is used to set up the pumping procedure table in the fracturing module of Petrel software based on the fracturing parameters of the fractured well A, and then perform hydraulic fracturing simulation based on the geomechanical model of the target stratum containing the wellbore to obtain the simulation results of hydraulic fracture propagation. The first correction module is used to correct the hydraulic fracture propagation simulation results and the cleavage distribution field of the target layer using the on-site fracturing construction monitoring curve of the fractured well A. After correction, the three-dimensional hydraulic fracture propagation morphology and the cleavage distribution field of the target layer of the fractured well A are obtained. The fourth modeling module is used to establish a post-pressurization production numerical model of the target layer in the Petrel software production module using two-phase flow parameters and the simulated three-dimensional hydraulic fracture propagation morphology and cleavage distribution field of the target layer. The second simulation module is used to set the amount of fracturing fluid to be retained based on the fracturing parameters of the fractured well A. Then, based on the post-fracturing production numerical model of the target formation, the Petrel software water injection algorithm is used to inject the amount of retained fracturing fluid into the reservoir through the hydraulic fracture, and to simulate the distribution field of the retained fracturing fluid in the hydraulic fracture and around the reservoir. The third simulation module is used to set the production regime based on the target formation post-fracturing production numerical model, based on the second simulation module, to simulate the daily gas and water production of the fractured well A. The second correction module is used to correct the production regime using the daily water and gas production data monitored on-site in the fractured well A, and to obtain the corrected production regime. The optimization module is used to modify the fracturing pump injection program based on the production system corrected by the second correction module. It reuses the first simulation module, the fourth modeling module, the second simulation module, and the third simulation module for data processing, monitors the cumulative gas production, stable production time, free gas reduction ratio, adsorbed gas reduction ratio, and liquid discharge efficiency, and uses the gas-water production comprehensive evaluation index as the scoring standard to adjust the pump injection program and fracturing construction parameters to obtain the fracturing optimization design drawing. Design Module: Used to guide the fracturing design of adjacent wells in the target reservoir using the fracturing optimization design chart obtained from the optimization module, thereby achieving fracturing optimization of deep coal and gas reservoirs.

[0045] The above-described embodiments are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. An optimized fracturing method for deep coal-rock gas reservoirs based on post-fracturing gas-water production characteristics analysis, characterized in that, Includes the following steps: S1. Using the reservoir properties and layered data of the target reservoir, a geological model of the target stratigraphic level, including the roof, floor and coal-rock sections, is established based on the three-dimensional geological modeling module of Petrel software. S2. Based on the rock mechanics parameters of the target reservoir and the geological model of the target stratum, establish the geomechanical model of the target stratum using the Visage geostress module of Petrel software, and eliminate interlayer unbalanced forces. S3. Using the completion parameters, wellbore trajectory parameters, and the target formation geomechanical model of the fractured well A, establish a target formation geomechanical model including the wellbore. S4. Based on the fracturing parameters of the fractured well A, set the pumping program table in the fracturing module of Petrel software, and then perform hydraulic fracturing simulation on the target layer geomechanical model containing the wellbore established in S3 to obtain the simulation results of hydraulic fracture propagation. S5. The simulation results of hydraulic fracture propagation and the cleavage distribution field of the target layer are corrected using the on-site fracturing construction monitoring curve of the fractured well A. After correction, the three-dimensional hydraulic fracture propagation morphology and the cleavage distribution field of the target layer of the fractured well A are obtained. S6. Using the two-phase flow parameters and the three-dimensional hydraulic fracture propagation morphology and cleavage distribution field of the target layer obtained from the simulation in S5, a post-pressurization production numerical model of the target layer is established in the production module of Petrel software. S7. Based on the fracturing parameters of the fractured well A, set the amount of fracturing fluid to be retained. Then, based on the post-fracturing production numerical model of the target formation, use the Petrel software water injection algorithm to inject the amount of retained fracturing fluid into the reservoir through the hydraulic fracture to simulate the distribution field of the retained fracturing fluid in the hydraulic fracture and around the reservoir. S8. Based on S7, use the target formation post-fracturing production numerical model to set the production regime and simulate the daily gas and water production of the fractured well A. S9. The production regime is corrected by using the daily water and gas production data monitored in the field of the fractured well A to obtain the corrected production regime. S10. Based on the production system corrected in S9, change the fracturing pump injection procedure and repeat S4, S6, S7, and S8. Monitor the cumulative gas production, stable production time, free gas reduction ratio, adsorbed gas reduction ratio, and liquid discharge efficiency. Use the gas-water production comprehensive evaluation index as the scoring standard to adjust the pump injection procedure and fracturing construction parameters to obtain the fracturing optimization design drawing. S11. Use the fracturing optimization design chart obtained in S10 to guide the fracturing design of adjacent wells in the target reservoir, thereby achieving fracturing optimization of deep coal and gas reservoirs.

2. The optimized fracturing method for deep coal and gas reservoirs based on post-fracturing gas-water production characteristics analysis according to claim 1, characterized in that, The specific process of S2 is as follows: Rock mechanics parameters are input into the geological model of the target stratum, and interpolation correction is performed using the sequential Gaussian simulation method. Then, boundary conditions are applied to the boundary of the geological model of the target stratum, and the grid and boundary conditions are continuously adjusted until the unbalanced force between the top and bottom plates and the coal and rock sections of the target stratum is less than 0.01 MPa.

3. The optimized fracturing method for deep coal and gas reservoirs based on post-fracturing gas-water production characteristics analysis according to claim 1 or 2, characterized in that, The rock mechanical parameters include Young's modulus and Poisson's ratio.

4. The optimized fracturing method for deep coal and rock gas reservoirs based on post-fracturing gas-water production characteristics analysis according to claim 1, characterized in that, The specific process of S5 is as follows: S5.1, Based on the geomechanical model of the target stratum containing the wellbore, randomly distribute the preset parameters of the cleavage; S5.2 Set up the pump injection program to simulate hydraulic fracturing using the fracturing module and monitor the fracturing construction curve; S5.

3. Compare the monitored fracturing operation curve with the on-site fracturing operation monitoring curve to obtain the first comparison error; S5.4 If the first comparison error is above the first preset value, then the parameters of the cleavage distribution are modified again, and S5.2 to S5.3 are repeated. S5.5 When the first comparison error is less than the first preset value, after the correction is completed, the fracture morphology at this time is the true three-dimensional hydraulic fracture propagation morphology of the fractured well A, and the distribution parameters of the cleavage at this time are the cleavage distribution field of the target layer.

5. The optimized fracturing method for deep coal and gas reservoirs based on post-fracturing gas-water production characteristics analysis according to claim 1 or 4, characterized in that, The first preset value is 5%; when using the field fracturing construction monitoring curve of the fractured well A to correct the hydraulic fracture propagation simulation results and the cleavage distribution field of the target layer, the correction is completed when the overall error between the daily gas production and daily water production obtained by numerical simulation and the field monitoring data is within 5%.

6. The optimized fracturing method for deep coal and gas reservoirs based on post-fracturing gas-water production characteristics analysis according to claim 1 or 4, characterized in that, The parameters of cleavage distribution include: cleavage distribution density, cleavage angle, and cleavage length.

7. The optimized fracturing method for deep coal and gas reservoirs based on post-fracturing gas-water production characteristics analysis according to claim 1, characterized in that, The specific process of S7 is as follows: S7.1 Calculate the total volume of retained fracturing fluid using the amount of retained fracturing fluid; S7.2 Obtain the average pressure and fracturing fluid viscosity inside the hydraulic fractures in the final corrected target layer geomechanical model in S5; S7.3 Set the injection regime in the Petrel software water injection algorithm, including constant injection pressure, total injection volume and injection fluid viscosity; the constant injection pressure is the average pressure in S7.2, and the injection fluid viscosity is the fracturing fluid viscosity in S7.2; S7.

4. Start the Petrel software water injection algorithm to inject liquid into the fracture using the wellbore as the injection port to simulate the retention process of fracturing fluid in the hydraulic fracture network of coal and rock, analyze the water saturation field around the fracture, and then obtain the simulated distribution field of the retained fracturing fluid in the hydraulic fracture and around the reservoir.

8. The optimized fracturing method for deep coal and gas reservoirs based on post-fracturing gas-water production characteristics analysis according to claim 1 or 7, characterized in that, In S7.1, the total volume of retained fracturing fluid is calculated using the following formula: Q=Q 总 ×(1-Ra) in, Q This refers to the amount of fracturing fluid retained. Q 总 The total liquid volume in the pumping procedure table; Ra This represents the fracturing fluid flowback rate.

9. The optimized fracturing method for deep coal and gas reservoirs based on post-fracturing gas-water production characteristics analysis according to claim 1, characterized in that, In step S11, the calculation method and steps for the comprehensive evaluation index of gas and water production are as follows: S11.1 Normalize the cumulative gas production, stable production time, free gas decrease rate, adsorbed gas decrease rate, and liquid discharge efficiency using the following formula: in, X in Represents normalized cumulative gas production, stable production time, decrease ratio of free gas / adsorbed gas, and liquid discharge efficiency; X i Represents the original values ​​of the five key parameters; X i-max , X i-min These are the maximum and minimum values ​​of each key parameter across all experimental cases; The drainage efficiency = Q 1 / Q ,in, Q 1 refers to the total amount of liquid discharged within the first 30 days of post-pressurization production; The ratio of free gas to adsorbed gas decreases = (G 总 -G 剩余 ) / G 总 Among them, G 总 G represents the total content of free / adsorbed gas in the geological model of the target stratum; 剩余 The total remaining free / adsorbed gas content in the geological model of the target stratum for 10 years of post-pressurization production; S11.2 Calculate the comprehensive gas-water production evaluation index S based on the weights of cumulative gas production, stable production time, percentage decrease in free gas, percentage decrease in adsorbed gas, and liquid discharge efficiency: in, X 1n Represents normalized cumulative gas production, X 2n Represents the period of stable production, X 3n Represents drainage efficiency, X 4n Represents the percentage of free gas that decreased. X 5n This represents the percentage decrease in adsorbed gas.

10. A system for implementing the deep coal and gas reservoir fracturing optimization method based on post-fracturing gas-water production characteristic analysis as described in any one of claims 1-9, characterized in that, include: The first modeling module is used to establish a geological model of the target stratigraphic level, including the roof, floor, and coal-rock sections, based on the reservoir physical property parameters and stratigraphic data of the target reservoir and the three-dimensional geological modeling module of Petrel software. The second modeling module is used to establish a geomechanical model of the target stratum based on the rock mechanical parameters of the target reservoir and the geological model of the target stratum, using the Visage geostress module of Petrel software, and to eliminate interlayer unbalanced forces. The third modeling module is used to establish a target layer geomechanical model including the wellbore using the completion parameters, wellbore trajectory parameters, and the target layer geomechanical model of the fractured well A. The first simulation module is used to set up the pumping procedure table in the fracturing module of Petrel software based on the fracturing parameters of the fractured well A, and then perform hydraulic fracturing simulation based on the geomechanical model of the target stratum containing the wellbore to obtain the simulation results of hydraulic fracture propagation. The first correction module is used to correct the hydraulic fracture propagation simulation results and the cleavage distribution field of the target layer using the on-site fracturing construction monitoring curve of the fractured well A. After correction, the three-dimensional hydraulic fracture propagation morphology and the cleavage distribution field of the target layer of the fractured well A are obtained. The fourth modeling module is used to establish a post-pressurization production numerical model of the target layer in the Petrel software production module using two-phase flow parameters and the simulated three-dimensional hydraulic fracture propagation morphology and cleavage distribution field of the target layer. The second simulation module is used to set the amount of fracturing fluid to be retained based on the fracturing parameters of the fractured well A. Then, based on the post-fracturing production numerical model of the target formation, the Petrel software water injection algorithm is used to inject the amount of retained fracturing fluid into the reservoir through the hydraulic fracture, and to simulate the distribution field of the retained fracturing fluid in the hydraulic fracture and around the reservoir. The third simulation module is used to set the production regime based on the target formation post-fracturing production numerical model, based on the second simulation module, and to simulate the daily gas and water production of the fractured well A. The second correction module is used to correct the production regime using the daily water and gas production data monitored in the field of the fractured well A, and to obtain the corrected production regime. The optimization module is used to modify the fracturing pump injection program based on the production system corrected by the second correction module. It reuses the first simulation module, the fourth modeling module, the second simulation module, and the third simulation module for data processing, monitors the cumulative gas production, stable production time, free gas reduction ratio, adsorbed gas reduction ratio, and liquid discharge efficiency, and uses the gas-water production comprehensive evaluation index as the scoring standard to adjust the pump injection program and fracturing construction parameters to obtain the fracturing optimization design drawing. Design Module: Used to guide the fracturing design of adjacent wells in the target reservoir using the fracturing optimization design chart obtained from the optimization module, thereby achieving fracturing optimization of deep coal and gas reservoirs.

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