Method, process and device for improving symmetry of crack, computer equipment and storage medium

Abstract

The invention provides a method, a process and a device for improving the symmetry of a crack, computer equipment and a storage medium. The method comprises the following steps: constructing a crack initiation and expansion resistance model; performing iterative solution on the crack initiation and extension resistance model to obtain the number of perforations of each cluster when the crack initiation and extension resistance of each cluster are equal; using the old well fracturing construction parameters to obtain a plurality of infilled well fracturing design parameters; sequentially simulating a plurality of infilled well fracturing simulation results according to the plurality of infilled well fracturing design parameters based on the dynamic crustal stress field model in the formation pressure deficit state by utilizing the number of the perforations of each cluster; and obtaining an optimal infilled well fracturing simulation result by utilizing the plurality of infilled well fracturing simulation results, obtaining infilled well fracturing design parameters corresponding to the optimal infilled well fracturing simulation result, and determining the infilled well fracturing design parameters as infilled well fracturing construction parameters. According to the method, the symmetry of the crack can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploitation, and particularly to a method, process, device, computer equipment and storage medium for improving fracture symmetry. Background Art

[0002] Currently, research on improving the fracturing transformation effect of shale gas infill wells has formed a set of infill well fracturing transformation methods based on the evolution of the four-dimensional in-situ stress field, mainly including optimizing the fracturing timing of infill wells, improving fracture complexity, expanding the swept area of transformation, and preventing cross-well channeling, etc., providing a solid theoretical basis for on-site fracturing construction. To achieve the target effect of infill well fracturing transformation, fracturing construction parameters are usually optimized from aspects such as perforation pattern, displacement combination, temporary plugging pattern, and sand addition method.

[0003] However, traditional methods do not consider the problem of asymmetric fracture propagation on both sides of infill wells caused by in-situ stress differences, that is, it causes fracture asymmetry, resulting in insufficient oil and gas production on one side.

[0004] Regarding the problem of asymmetric fracture propagation on both sides of the wellbore caused by the difference in the dynamic evolution of in-situ stress due to the difference in the production regime of old wells on both sides of infill wells, in the currently disclosed infill well fracturing technologies, no effective solution has been given. Therefore, it is necessary to research and propose a targeted fracturing technology that can change the liquid injection flow rate of fracture clusters on both sides of the infill wellbore, control the formation of fracture dominant channels, promote the balance of fracture extension on both sides of the wellbore, and improve the segmented fracturing transformation effect of shale gas infill wells. Summary of the Invention

[0005] Based on this, in view of the above technical problems, it is necessary to provide a method, process, device, computer equipment and storage medium for improving fracture symmetry.

[0006] A method for improving fracture symmetry includes:

[0007] Obtaining drilling and completion fluid parameters, geological data, old well production parameters, and old well fracturing construction parameters;

[0008] Based on the drilling and completion fluid parameters, the geological data, the old well production parameters, and the old well fracturing construction parameters, constructing a fracture initiation and propagation resistance model;

[0009] Performing iterative solution on the fracture initiation and propagation resistance model to obtain the number of perforations for each cluster when the fracture initiation and extension resistances of each cluster are equal;

[0010] Using the old well fracturing construction parameters to obtain multiple fracturing design parameters for infill wells;

[0011] Obtaining a dynamic in-situ stress field model under the formation pressure depletion state;

[0012] Using the number of perforations in each cluster, based on the dynamic in-situ stress field model under the formation pressure depletion state, and successively simulating multiple stimulation simulation results of infill wells according to multiple infill well fracturing design parameters;

[0013] Using multiple stimulation simulation results of infill wells, obtaining an optimized stimulation simulation result of an infill well, and obtaining the infill well fracturing design parameters corresponding to the optimized stimulation simulation result of the infill well, and determining them as infill well fracturing construction parameters.

[0014] In one embodiment, the drilling and completion fluid parameters include perforation parameters, wellbore parameters, and fracturing fluid performance parameters;

[0015] The steps of constructing a fracture initiation and propagation resistance model based on the drilling and completion fluid parameters, the geological data, the production parameters of the old wells, and the fracturing construction parameters of the old wells include:

[0016] According to the dynamic in-situ stress change model, constructing an initiation point stress model;

[0017] Solving the initiation point stress model to obtain a fluid pressure calculation model;

[0018] According to the fracturing construction parameters of the old wells, establishing an old well fracture propagation model to obtain an old well fracturing fracture simulation result;

[0019] According to the old well fracturing fracture simulation result, establishing an initiation point induced stress field model;

[0020] Obtaining wellbore parameters and fracturing fluid performance parameters;

[0021] Based on the wellbore parameters and the fracturing fluid performance data, using fluid mechanics methods to construct a target wellbore frictional resistance calculation model along the wellbore;

[0022] Obtaining perforation parameters;

[0023] Using the perforation parameters and the fracturing fluid performance parameters to construct a perforation frictional resistance calculation model;

[0024] Using the fluid pressure calculation model, the frictional resistance calculation model along the wellbore, the initiation point induced stress calculation model, and the perforation frictional resistance calculation model to construct the fracture initiation and propagation resistance model.

[0025] In one embodiment, the steps of iteratively solving the fracture initiation and propagation resistance model to obtain the number of perforations in each cluster when the fracture initiation and extension resistances of each cluster are equal include:

[0026] Setting an initial value of the number of perforations in each cluster in the perforation frictional resistance calculation model, and keeping the initial values of the number of perforations in each cluster consistent;

[0027] Adjust the perforation number of each cluster in the perforation friction calculation model one by one until the fracture initiation and propagation resistances of each cluster are equal, so as to determine the perforation number of each cluster.

[0028] A process for improving fracture symmetry includes:

[0029] Adopt the method described in any of the above embodiments to determine the fracturing construction parameters of the infill well and the perforation number of each cluster in the fracturing section;

[0030] Utilize the determined fracturing construction parameters of the infill well and the perforation number of each cluster in the fracturing section to perform the following steps:

[0031] 1) Perform perforation operations according to the perforation number of each cluster in the fracturing section;

[0032] 2) Acid pretreatment operation;

[0033] 3) According to the fracturing construction parameters of the infill well, during the fracture creating operation and the proppant adding operation, sequentially perform the small particle size temporary plugging agent adding operation, the large particle size temporary plugging agent adding operation, and the low viscosity slickwater carrying proppant construction operation;

[0034] 4) According to the fracturing construction parameters of the infill well, perform displacement operation;

[0035] Repeat the above steps 1) to 4) until all fracturing sections of the infill well are constructed.

[0036] In one embodiment, the fracturing construction parameters of the infill well include the perforating gun length;

[0037] Utilize the perforation number of each cluster in the fracturing section to determine the perforating gun length;

[0038] Use the perforating gun with the perforating gun length to perform the perforation operation.

[0039] In one embodiment, the fracturing construction parameters of the infill well further include the preset addition times and the preset addition time of the small particle size temporary plugging agent;

[0040] The steps of the small particle size temporary plugging agent adding operation include:

[0041] Perform the first small particle size temporary plugging agent adding operation according to the preset addition times and the preset addition time of the small particle size temporary plugging agent;

[0042] Observe the change of the construction pressure rise and the change of the microseismic monitoring event points to judge the adaptability of the temporary plugging mode of the first small particle size temporary plugging agent adding operation;

[0043] When the plugging mode adaptability of the first small particle size temporary plugging agent addition operation meets the plugging requirements of the first small particle size temporary plugging agent addition operation, subsequent small particle size temporary plugging agent addition operations are carried out according to the preset addition times and preset addition time of the small particle size temporary plugging agent;

[0044] When the plugging mode adaptability of the first small particle size temporary plugging agent addition operation is lower than the plugging requirements of the first small particle size temporary plugging agent addition operation, adjust the preset addition times and preset addition time of the small particle size temporary plugging agent, determine the optimized preset addition times and preset addition time of the small particle size temporary plugging agent, and carry out subsequent small particle size temporary plugging agent addition operations according to the optimized preset addition times and preset addition time of the small particle size temporary plugging agent.

[0045] In one embodiment, the fracturing construction parameters of the infill well further include the preset addition times and preset addition time of the large particle size temporary plugging agent;

[0046] The steps of the large particle size temporary plugging agent addition operation include:

[0047] Carry out the first large particle size temporary plugging agent addition operation according to the preset addition times and preset addition time of the large particle size temporary plugging agent;

[0048] Observe the change of the construction pressure rise and the change of the microseismic monitoring event points to judge the plugging mode adaptability of the first large particle size temporary plugging agent addition operation;

[0049] When the plugging mode adaptability of the first large particle size temporary plugging agent addition operation meets the plugging requirements of the first large particle size temporary plugging agent addition operation, carry out subsequent large particle size temporary plugging agent addition operations according to the preset addition times and preset addition time of the large particle size temporary plugging agent;

[0050] When the plugging mode adaptability of the first large particle size temporary plugging agent addition operation is lower than the plugging requirements of the first large particle size temporary plugging agent addition operation, adjust the preset addition times and preset addition time of the large particle size temporary plugging agent, determine the optimized preset addition times and preset addition time of the large particle size temporary plugging agent, and carry out subsequent large particle size temporary plugging agent addition operations according to the optimized preset addition times and preset addition time of the large particle size temporary plugging agent.

[0051] A device for improving fracture symmetry includes:

[0052] A data acquisition module for acquiring drilling and completion fluid parameters, geological data, old well production parameters and old well fracturing construction parameters;

[0053] The first model construction module is used to construct a fracture initiation and propagation resistance model based on the drilling and completion fluid parameters, the geological data, the production parameters of the old well, and the fracturing construction parameters of the old well;

[0054] The perforation number solving module is used to perform iterative solution on the fracture initiation and propagation resistance model to obtain the perforation numbers of each cluster when the fracture initiation and extension resistances of each cluster are equal;

[0055] The design parameter determination module is used to obtain multiple fracturing design parameters for infill wells by using the fracturing construction parameters of the old well;

[0056] The second model acquisition module is used to acquire a dynamic in-situ stress field model under the formation pressure deficit state;

[0057] The fracturing simulation module is used to use the perforation numbers of each cluster, based on the dynamic in-situ stress field model under the formation pressure deficit state, and successively simulate multiple fracturing simulation results of infill wells according to multiple fracturing design parameters for infill wells;

[0058] The parameter determination module is used to use multiple fracturing simulation results of infill wells to obtain an optimized fracturing simulation result of an infill well, and obtain the fracturing design parameter of the infill well corresponding to the optimized fracturing simulation result of the infill well, and determine it as the fracturing construction parameter of the infill well.

[0059] A computer device includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of the method for improving fracture symmetry in any of the above embodiments are implemented.

[0060] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for improving fracture symmetry in any of the above embodiments are implemented.

[0061] For the above method, process, device, computer device, and storage medium for improving fracture symmetry, iterative solution is performed on the fracture initiation and propagation resistance model to obtain the perforation numbers of each cluster when the fracture initiation and extension resistances of each cluster are equal. That is to say, when the fracture initiation and extension resistances of each cluster are equal, the problem of uneven fracture initiation and propagation between clusters can be solved in advance, so as to more specifically solve the problem of asymmetric fracture propagation within the cluster, that is, improve fracture symmetry and improve the fracturing treatment effect. Description of the Drawings

[0062] Figure 1 It is a schematic flow chart of the method for improving fracture symmetry in an embodiment;

[0063] Figure 2 It is a diagram of the minimum horizontal in-situ stress change in the fracture extension direction;

[0064] Figure 3 The construction pressure curve diagram in a new method for improving the symmetry of hydraulic fracturing cracks in shale gas infill wells in an embodiment;

[0065] Figure 4 The structural block diagram of a device for improving crack symmetry in an embodiment;

[0066] Figure 5 The internal structure diagram of a computer device in an embodiment. Detailed implementation manners

[0067] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0068] Embodiment 1

[0069] In this embodiment, as Figure 1 shown, a method for improving crack symmetry is provided, which includes:

[0070] Step 110, obtaining drilling and completion fluid parameters, geological data, production parameters of old wells, and fracturing construction parameters of old wells.

[0071] In this embodiment, the drilling and completion fluid parameters include perforation parameters, wellbore parameters, and fracturing fluid performance parameters, and the geological data includes logging data, mud logging data, and core experiment data.

[0072] Step 120, constructing a crack initiation and propagation resistance model based on the drilling and completion fluid parameters, the geological data, the production parameters of old wells, and the fracturing construction parameters of old wells.

[0073] Step 130, performing iterative solution on the crack initiation and propagation resistance model to obtain the number of perforations in each cluster when the crack initiation and extension resistances of each cluster are equal.

[0074] In this embodiment, the uneven expansion of each cluster of cracks within a section is caused by the difference in the crack initiation and propagation resistances of each cluster. The crack initiation and propagation resistances mainly include in-situ stress, wellbore friction along the way, perforation friction, and induced stress, etc. Among them, the induced stress is due to the cracks formed in the already fractured section having a squeezing effect on the surrounding rocks, generating additional squeezing stress, and the farther away from the crack position, the weaker the induced stress. Since the wellbore friction and the induced stress received by each cluster position in the section to be fractured are different, the same liquid intake resistance for each cluster can be achieved by changing the perforation friction of each cluster. Changing the perforation friction of each cluster is achieved by fixing the perforation aperture and changing the number of perforations.

[0075] Step 140, obtaining multiple fracturing design parameters for infill wells by using the fracturing construction parameters of old wells.

[0076] Step 150: Obtain the dynamic in-situ stress field model under the formation pressure depletion state.

[0077] In this embodiment, the construction process of the dynamic in-situ stress field model under the formation pressure depletion state is as follows: Based on well logging data, mud logging data, core experiment data, hydraulic fracturing inversion data of surrounding old wells, and production data of old wells, basic data such as physical property parameters, rock mechanics parameters, in-situ stress parameters, and natural fracture distribution parameters of the infill wells are obtained.

[0078] According to the obtained well logging data, etc., use commercial geological modeling software such as Petrel and Fracman to establish a block geological model. The dynamic in-situ stress field model considering formation pressure depletion is established on the basis of the block geological model. First, establish a block in-situ stress field model to simulate the distribution of the initial in-situ stress field of the block. Then, according to core experiment data and production data of old wells, etc., use commercial numerical simulation software such as CMG and Eclipse to establish a production capacity simulation model, and build a block dynamic in-situ stress field model based on the two. Use the production capacity simulation model to simulate the formation pressure change according to the production system parameters and production cycle parameters of old wells, etc., to quantitatively characterize the formation pressure depletion state. After that, on the basis of the original in-situ stress field model, update the formation pressure, and through coupled simulation, obtain the dynamic in-situ stress field model considering the formation pressure depletion state, so as to simulate the change of the in-situ stress field of the block during the production process after hydraulic fracturing of old wells.

[0079] Step 160: Based on the dynamic in-situ stress field model under the formation pressure depletion state and according to multiple hydraulic fracturing design parameters of infill wells, use the number of perforations in each cluster to sequentially simulate multiple hydraulic fracturing simulation results of infill wells.

[0080] In this embodiment, on the basis of the dynamic in-situ stress field model considering the formation pressure depletion state, use commercial hydraulic fracturing design software such as Gohfer and Petrel to simulate the hydraulic fracturing simulation results of infill wells.

[0081] Step 170: Use the multiple hydraulic fracturing simulation results of infill wells to obtain the optimized hydraulic fracturing simulation result of infill wells, and obtain the corresponding hydraulic fracturing design parameters of the infill wells, and determine them as the hydraulic fracturing construction parameters of infill wells.

[0082] In this embodiment, step 160 simulates and analyzes the fracture propagation law under different construction displacement and scale conditions of the infill well, compares the morphological differences between the fractures of the infill well and the old well, and judges the risk of fracture connection between the two. The risk of fracture connection between the two is judged based on the following design objectives as risk points. When the risk points are reached, the fracturing construction parameters need to be adjusted. Taking 80% - 90% of the half fracture length of the infill well as the difference between the well spacing and the half fracture length of the old well as the design objective, based on the fracturing design parameters of the old well, including liquid volume, sand volume, displacement, sand addition mode, temporary plugging mode, etc., using the calculation method given in step 130, calculate the number of perforations for each cluster in the fracturing section. According to the sequence of fracturing construction parameters such as fracturing fluid viscosity, liquid volume, and displacement, set the change interval and gradually reduce the parameter values. Use different fracturing design parameters of the infill well to simulate data such as fracture morphology, bottom hole pressure, and proppant placement state in different situations, and select the most suitable fracturing construction parameters of the infill well that are closest to the design objective from them.

[0083] In one embodiment, the drilling and completion fluid parameters include perforation parameters, wellbore parameters, and fracturing fluid performance parameters;

[0084] The steps of constructing the fracture initiation and propagation resistance model based on the drilling and completion fluid parameters, the geological data, the old well production parameters, and the old well fracturing construction parameters include:

[0085] According to the in-situ stress dynamic change model, construct the initiation point stress model;

[0086] Solve the initiation point stress model to obtain the fluid pressure calculation model;

[0087] According to the old well fracturing construction parameters, establish the old well fracture propagation model to obtain the old well fracturing fracture simulation results;

[0088] According to the old well fracturing fracture simulation results, establish the initiation point induced stress field model;

[0089] Obtain the wellbore parameters and fracturing fluid performance parameters;

[0090] Based on the wellbore parameters and the fracturing fluid performance data, use the fluid mechanics method to construct the target wellbore friction calculation model along the well path;

[0091] Obtain the perforation parameters;

[0092] Use the perforation parameters and the fracturing fluid performance parameters to construct the perforation friction calculation model;

[0093] Use the fluid pressure calculation model, the friction calculation model along the well path, the initiation point induced stress calculation model, and the perforation friction calculation model to construct the fracture initiation and propagation resistance model.

[0094] In this embodiment, to calculate the initiation and propagation resistance of each cluster of fractures in the calculation section, the in-situ stress, wellbore friction along the way, induced stress, and perforation friction need to be calculated separately. The expression of the fracture initiation and propagation resistance model is as follows:

[0095] p a,i = p wf,i + p cf,i + p id,i + p pf,i i = 1, 2, …, n

[0096] In the formula, p a,i is the fracture initiation and propagation resistance, Pa; p wf,i is the fluid pressure required to overcome the in-situ stress, Pa; p cf,i is the friction along the way from the wellbore heel to the position of each cluster, Pa; p id,i is the induced stress of the fractures in the already fractured section on the position of each cluster, Pa; p pf,i is the perforation friction of each cluster, Pa. n is the number of clusters in the section.

[0097] Generally, the fracture section block is assumed to be an in-situ stress mean model, that is, the in-situ stress at the positions of each cluster in the section is equal. This is acceptable in the case of a rough assessment of the formation in-situ stress. However, since this patent involves the detailed calculation of the number of perforations in each cluster, the in-situ stress distribution in the section needs to be accurately calculated. In addition, the presence of horizontal wellbores and perforations in the reservoir will cause local stress concentration, resulting in a change in the in-situ stress at the fracture initiation point near the perforations. It is necessary to calculate the fluid pressure required for reservoir fracture according to the in-situ stress redistribution model. Therefore, the process of calculating the fluid pressure required to overcome the in-situ stress for reservoir fracture includes first describing the in-situ stress distribution in the section according to the logging data and the block in-situ stress field model, then calculating the initiation point stress according to the in-situ stress redistribution model, and finally solving the model to obtain the required fluid pressure.

[0098] The expression of the fluid pressure calculation model is as follows:

[0099]

[0100] In the formula, σ H,i , σ h,i , σ v,i are the maximum horizontal principal stress, minimum horizontal principal stress, and vertical stress of the reservoir obtained based on the geomechanics model, Pa; τ xy,i is the in-plane shear stress of the reservoir, Pa; σ s is the tensile strength of the reservoir rock, Pa; θ and θ′ are the perforation phase angle and perforation initiation angle respectively, dimensionless.

[0101] The expression of the calculation model for the friction along the target wellbore is as follows:

[0102]

[0103]

[0104]

[0105] In the formula, C cf is the wellbore friction coefficient, Pa·s / m 3 ; l j is the distance from the j-th cluster of fractures to the wellbore heel, m; q w,j and q T are the fluid injection flow rate of the j-th cluster of fractures and the total wellbore flow rate respectively, m 3 / s; K is the fracturing fluid consistency coefficient, Pa·s n′ ; n′ is the flow behavior index, dimensionless.

[0106] The induced stress p id,i is calculated according to the displacement discontinuity method. The fracture aperture parameter used in the model needs to refer to the old well fracturing simulation results. The expression of the induced stress calculation model at the fracture initiation point is:

[0107] p id,i = A ns D s + A nn D n

[0108]

[0109] In the formula, A ns and A nn are the boundary stress influence coefficients, Pa / m; D n and D s are the normal and tangential displacement components, m; G is the rock shear modulus, GPa; x, y are the coordinates of any point in the target area, m; a is the fracture element length, m; γ is the fracture extension angle; v is the Poisson's ratio of the reservoir rock, dimensionless.

[0110] The expression of the perforation friction calculation model is:

[0111]

[0112] In the formula, ρ s is the fracturing fluid density, kg / m 3 ; n f,i is the number of perforations in the i-th cluster, dimensionless; d f,i is the perforation diameter, mm; C d is the perforation friction coefficient, dimensionless.

[0113] To make the fluid injection resistance of each cluster the same, then there is:

[0114] p a,1= p a,2 = p a,i = p a,n

[0115] The above conditions can be achieved by adjusting the friction of each cluster of perforations and solved by the iterative method. Referring to the perforation quantity of the surrounding old wells, the perforation quantity of the fracture cluster closest to the wellbore root can be fixed first, and then, based on this, the perforation quantity is gradually increased to obtain the perforation quantity of other clusters until the perforation quantity of all clusters in the section is solved.

[0116] In one embodiment, the step of iteratively solving the fracture initiation and propagation resistance model to obtain the perforation quantity of each cluster when the fracture initiation and extension resistance of each cluster are equal includes:

[0117] Set the initial value of the perforation quantity of each cluster in the perforation friction calculation model and keep the initial values of the perforation quantity of each cluster consistent;

[0118] Adjust the perforation quantity of each cluster in the perforation friction calculation model one by one until the fracture initiation and propagation resistance of each cluster are equal to determine the perforation quantity of each cluster.

[0119] In this embodiment, aiming at the problem of asymmetric fracture propagation caused by non-uniform distribution of in-situ stress during the fracturing process of infill wells, a new fracturing method for promoting the balanced liquid intake of fractures on both sides of the wellbore in infill well fracturing is proposed, which has the characteristics of clear method, reasonable design, simple and easy operation, etc. By referring to the fracturing construction parameters of the surrounding old wells, the present invention can ensure that the fracturing construction method has good adaptability to the target formation. Adding small-particle-size temporary plugging agents can better plug the fracture ends, promote fracture diversion, and realize complex fracture formation. Adding large-particle-size temporary plugging agents can accumulate at the fracture mouth, reduce the liquid intake of the dominant fracture channel, promote the flow of fracturing fluid to the high in-situ stress area, and realize the fracturing transformation sequence of the low in-situ stress area first and then the high in-situ stress area. Using low-viscosity slickwater fracturing can control the scale of fracture extension and avoid the inter-well fracture communication. In summary, the present invention can better achieve the balanced transformation of infill wells, and the transformation volume is increased by more than 10% compared with the surrounding old wells.

[0120] For the above method of improving fracture symmetry, the fracture initiation and propagation resistance model is iteratively solved to obtain the perforation quantity of each cluster when the fracture initiation and extension resistance of each cluster are equal. That is to say, when the fracture initiation and extension resistance of each cluster are equal, the problem of unbalanced fracture initiation and propagation between clusters can be solved in advance, so as to more specifically solve the problem of asymmetric fracture extension within the cluster, that is, improve fracture symmetry and improve the fracturing transformation effect.

[0121] It should be understood that although Figure 1The steps in the flowchart are shown in sequence according to the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise clearly stated in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 At least a part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed alternately or in rotation with at least a part of other steps or sub-steps or stages of other steps.

[0122] Embodiment 2

[0123] In this embodiment, a process for improving fracture symmetry is provided, including:

[0124] Using the method for improving fracture symmetry described in the above embodiment, determine the fracturing construction parameters of the infill well and the number of perforations in each cluster within the fracturing interval;

[0125] Utilize the determined fracturing construction parameters of the infill well and the number of perforations in each cluster within the fracturing interval to perform the following steps:

[0126] 1) According to the number of perforations in each cluster within the fracturing interval, perform perforation operations;

[0127] 2) Acid pretreatment operations;

[0128] 3) According to the fracturing construction parameters of the infill well, during the fracture creating operation and the proppant adding operation, sequentially perform the operations of adding small particle size temporary plugging agents, adding large particle size temporary plugging agents, and the operation of injecting low-viscosity slickwater carrying proppants;

[0129] 4) According to the fracturing construction parameters of the infill well, perform displacement operations;

[0130] Repeat the above steps 1) to 4) until all fracturing intervals of the infill well are completed.

[0131] For the perforation operation of the fracturing interval, adopt the spiral perforation method, the perforation phase angle is 60°, the perforating gun has 20 holes / m, and the length of the perforating gun is adjusted according to the number of perforation holes in each cluster. For the first interval, the coiled tubing perforation operation technology is adopted, and for the intervals from the second to the last, the bridge plug perforation combination technology is adopted.

[0132] The acid used in on-site construction is usually 15% hydrochloric acid. The acid consumption for the first interval is set to 40m 3 , and for other intervals, the acid consumption is set to 15 - 30m according to the distribution of minerals such as calcite and shale and the distribution of drilling fluid leakage points, etc. 3 . For the acid injection process parameters, the displacement is 1.5 - 2.0m 3 / min. After the acid injection is completed, increase the displacement to 4 m 3 / min to promote uniform acid intake in each perforation cluster.

[0133] In this embodiment, the fracturing construction parameters of the infill well obtained in the above embodiment are adopted, including optimized parameters such as the amount of gel fluid, construction displacement, sand addition timing, sand addition type, and sand ratio, etc., for the preliminary fracturing construction. The displacement is increased to the highest stage by means of stepped displacement increase. In this way, it can be ensured that the fracturing fluid in the low displacement stage when the construction pressure is low mainly enters the perforation clusters on the side of low in-situ stress. After the displacement is increased, it is beneficial to form a dominant channel for the fracture in the area on this side of the wellbore.

[0134] In this embodiment, for the stepped displacement increase, a step can be set every time the displacement increases by 3.0 - 4.0 m3 / min, and each step stays for 3.0 - 8.0 min. When the displacement is increased to about 80% of the optimized design maximum displacement, stop increasing the displacement and start the main fracturing construction.

[0135] In this embodiment, the operation at this stage is to block the dominant channel at the end of the fracture, promote the fracture to turn, and meet the requirements of complex fracture formation. Since the fracturing transformation sequence is from the low in-situ stress area to the high in-situ stress area, therefore, small particle size temporary plugging agents need to be added twice at 30% and 80% of the total construction fluid volume within a single stage. According to the fracturing construction parameters of the infill well obtained in the above embodiment, 20 / 80 mesh temporary plugging agents are used, with a single dosage of 150 - 200 kg and an addition time of 180 - 240 s. After the temporary plugging agent arrives, observe the change in the construction pressure rise and the change in the microseismic monitoring event points. If the increase in the construction pressure exceeds the average level of the construction pressure rise during the temporary plugging of the surrounding old wells, or there are obvious new microseismic event points on the low in-situ stress side of the wellbore, it is considered that the current temporary plugging mode has good adaptability. If the temporary plugging requirement is not met, for the subsequent fracturing stage construction, optimize the temporary plugging mode in the order of first increasing the temporary plugging agent by 50 kg each time and then shortening the addition time by 15 - 30 s. Generally, on the basis of the initial temporary plugging mode, optimizing 1 - 3 times can meet the temporary plugging requirement.

[0136] In this embodiment, after the large - particle - size temporary plugging agent enters the formation, it aggregates into lumps with each other and will preferentially enter the dominant fracture channels with larger fracture widths. Since it is difficult to migrate towards the fracture end direction, it will mainly accumulate near the fracture mouth, which can play a role in reducing the liquid inflow rate of the dominant fracture channels, thereby increasing the liquid inflow rate of the fractures on the high - in - situ - stress side of the wellbore. The dosing time of the large - particle - size temporary plugging agent is set to 60% of the total construction liquid volume. The 10 / 40 - mesh temporary plugging agent is used, with a single - time dosage of 50 - 100 kg and an addition time of 120 - 180 s. After the temporary plugging agent arrives, observe whether the increase in the construction pressure exceeds 3.0 MPa, and whether the construction pressure step after temporary plugging is significantly higher than that before temporary plugging. If so, it is considered that the temporary plugging requirement is met; if not, for the subsequent fracturing stages, optimize the temporary plugging method by increasing the 20 / 80 - mesh temporary plugging agent by 25 - 50 kg each time. The small - particle - size temporary plugging agent is easier to aggregate into lumps when mixed with the large - particle - size temporary plugging agent, and has a stronger ability to plug the fracture mouth.

[0137] In this embodiment, for the fracturing of infill wells, it is necessary to avoid the connection between the fractures and the fractures of the surrounding old wells, otherwise it will have a greater negative impact on the productivity of the old wells. Under the condition of maintaining a certain level of liquid - using intensity and sand - adding intensity, low - viscosity slickwater fracturing construction is adopted, which can not only control the fracture length but also is beneficial to improving the fracture - creating complexity. The fracturing construction parameters of the infill wells obtained by using the above - mentioned embodiment, including the proportions of low - viscosity slickwater, medium - viscosity slickwater, and high - viscosity slickwater, are set with reference to the fracturing construction parameters of the surrounding old wells. On this basis, gradually reduce the usage amounts of medium - viscosity and high - viscosity slickwater and increase the usage amount of low - viscosity slickwater, which can be carried out at a rate of reducing 50 - 100 m 3 per stage, and observe the change of the construction pressure curve. If the construction pressure curve shows a rapid increase, stop adding sand and increase the measure of medium - top gel fluid to promote the migration of the proppant in the fracture towards the far - well area, so that the construction pressure curve returns to a stable state.

[0138] In this embodiment, the sand - adding method in the sand - adding operation is mainly in the form of slugs, and the length of the sand - adding slug is adjusted according to the change of the construction pressure. When the fracturing fluid is low - viscosity slickwater, appropriately reduce the length of the sand - adding slug. The overall sand - adding ratio is set with reference to the fracturing parameters of the surrounding old wells. Before the first addition of the small - particle - size temporary plugging agent, the sand - adding ratio does not exceed 70% of the highest sand ratio to avoid excessive sand settlement near the wellbore, resulting in a too - rapid increase in the construction pressure.

[0139] In this embodiment, the displacement operation refers to using the displacement fluid to displace the liquid in the original fracture. After the low - viscosity slickwater carrying the proppant completes the designed sand - adding amount in the construction operation, design the displacement fluid volume according to 110% - 120% of the wellbore volume. Among them, 40% - 50% of the displacement fluid volume uses high - viscosity slickwater to sweep the wellbore to prevent sand settlement in the wellbore, and the remaining displacement fluid volume is low - viscosity slickwater.

[0140] In this embodiment, the construction of the remaining stages repeats the process from step 1) to step 4) until the construction of all fracturing stages is completed.

[0141] In one embodiment, the encrypted well fracturing construction parameters further include the preset addition times and the preset addition time of the small-particle-size temporary plugging agent;

[0142] The steps of the small-particle-size temporary plugging agent addition operation include:

[0143] Perform the first addition operation of the small-particle-size temporary plugging agent according to the preset addition times and the preset addition time of the small-particle-size temporary plugging agent;

[0144] Observe the change of the construction pressure rise and the change of the microseismic monitoring event points to judge the adaptability of the temporary plugging mode of the first addition operation of the small-particle-size temporary plugging agent;

[0145] When the adaptability of the temporary plugging mode of the first addition operation of the small-particle-size temporary plugging agent meets the temporary plugging requirements of the first addition operation of the small-particle-size temporary plugging agent, perform subsequent addition operations of the small-particle-size temporary plugging agent according to the preset addition times and the preset addition time of the small-particle-size temporary plugging agent;

[0146] When the adaptability of the temporary plugging mode of the first addition operation of the small-particle-size temporary plugging agent is lower than the temporary plugging requirements of the first addition operation of the small-particle-size temporary plugging agent, adjust the preset addition times and the preset addition time of the small-particle-size temporary plugging agent, determine the optimized preset addition times and the optimized preset addition time of the small-particle-size temporary plugging agent, and perform subsequent addition operations of the small-particle-size temporary plugging agent according to the optimized preset addition times and the optimized preset addition time of the small-particle-size temporary plugging agent.

[0147] In one embodiment, the encrypted well fracturing construction parameters further include the preset addition times and the preset addition time of the large-particle-size temporary plugging agent;

[0148] The steps of the large-particle-size temporary plugging agent addition operation include:

[0149] Perform the first addition operation of the large-particle-size temporary plugging agent according to the preset addition times and the preset addition time of the large-particle-size temporary plugging agent;

[0150] Observe the change of the construction pressure rise and the change of the microseismic monitoring event points to judge the adaptability of the temporary plugging mode of the first addition operation of the large-particle-size temporary plugging agent;

[0151] When the adaptability of the temporary plugging mode of the first addition operation of the large-particle-size temporary plugging agent meets the temporary plugging requirements of the first addition operation of the large-particle-size temporary plugging agent, perform subsequent addition operations of the large-particle-size temporary plugging agent according to the preset addition times and the preset addition time of the large-particle-size temporary plugging agent;

[0152] When the adaptability of the temporary plugging mode in the first large-particle-size temporary plugging agent addition operation is lower than the temporary plugging requirements of the first large-particle-size temporary plugging agent addition operation, adjust the preset addition times and preset addition time of the large-particle-size temporary plugging agent, determine the optimized preset addition times and preset addition time of the large-particle-size temporary plugging agent, and perform subsequent large-particle-size temporary plugging agent addition operations according to the optimized preset addition times and preset addition time of the large-particle-size temporary plugging agent.

[0153] In this embodiment, a new fracturing method for promoting the balanced liquid intake of fractures on both sides of the wellbore during the fracturing of infill wells is proposed to address the problem of asymmetric fracture propagation caused by non-uniform distribution of in-situ stress during the fracturing of infill wells. It has the characteristics of clear method, reasonable design, simple and easy operation, etc. By referring to the fracturing construction parameters of surrounding old wells, the present invention can ensure that the fracturing construction method has good adaptability to the target formation. Adding small-particle-size temporary plugging agents can better plug the fracture ends, promote fracture diversion, and achieve complex fracture creation. Adding large-particle-size temporary plugging agents can accumulate at the fracture mouth, reduce the liquid intake of the dominant fracture channel, promote the flow of fracturing fluid to the high in-situ stress area, and achieve the fracturing transformation sequence of first the low in-situ stress area and then the high in-situ stress area. Using low-viscosity slickwater fracturing can control the scale of fracture extension and avoid fracture communication between wells. In summary, the present invention can better achieve balanced transformation of infill wells, and the transformed volume is increased by more than 10% compared with surrounding old wells.

[0154] Embodiment III

[0155] In this embodiment, a new method for improving the symmetry of fracturing fractures in shale gas infill wells is provided, including:

[0156] (1) Simulate the dynamic change of the reservoir in-situ stress field

[0157] Obtain basic data such as physical property parameters, rock mechanics parameters, in-situ stress parameters, and natural fracture distribution parameters of infill wells based on conventional logging data, mud logging data, core experiment data, fracturing inversion data of surrounding old wells, and production data of old wells.

[0158] According to the acquired logging data, etc., a block geological model is established using commercial geological modeling software such as Petrel and Fracman. The dynamic in-situ stress field model considering formation pressure depletion is based on the block geological model. First, a block in-situ stress field model is established to simulate the distribution of the initial in-situ stress field of the block. Then, based on data such as core experiments and production of old wells, a production capacity simulation model is established using commercial numerical simulation software such as CMG and Eclipse. A dynamic in-situ stress field model considering formation pressure depletion is constructed based on the above two models. The production capacity simulation model is used to simulate the formation pressure change according to parameters such as the production regime and production cycle of old wells, and to quantitatively characterize the state of formation pressure depletion. After that, based on the original in-situ stress field model, the formation pressure is updated, and through coupled simulation, a dynamic in-situ stress field model considering formation pressure depletion is obtained, so as to simulate the change of the regional in-situ stress field during the post-fracturing production process of old wells.

[0159] (2) Determination of the number of perforations

[0160] The uneven fracture propagation of each cluster within the section is caused by the differences in the fracture initiation and propagation resistance of each cluster. The fracture initiation and propagation resistance mainly includes in-situ stress, wellbore friction along the way, perforation friction, and induced stress, etc. Among them, the induced stress is due to the fact that the fractures formed in the already fractured section have a squeezing effect on the surrounding rocks, generating additional squeezing stress, and the farther away from the fracture position, the weaker the induced stress. Since the wellbore friction and the induced stress received by each cluster position in the section to be fractured are different, the same liquid intake resistance for each cluster can be achieved by changing the perforation friction of each cluster. Changing the perforation friction of each cluster is achieved by fixing the perforation aperture and changing the number of perforations.

[0161] In this embodiment, to calculate the fracture initiation and propagation resistance of each cluster within the section, the in-situ stress, wellbore friction along the way, induced stress, and perforation friction need to be calculated separately. The expression of the fracture initiation and propagation resistance model is:

[0162] p a,i =p wf,i +p cf,i +p id,i +p pf,i i = 1, 2, …, n

[0163] In the formula, p a,i is the fracture initiation and propagation resistance, Pa; p wf,i is the fluid pressure required to overcome the in-situ stress, Pa; p cf,i is the friction along the way from the wellbore heel to the position of each cluster, Pa; p id,i is the induced stress of the fractures in the already fractured section on the position of each cluster, Pa; p pf,i is the perforation friction of each cluster, Pa. n is the number of clusters within the section.

[0164] Generally, the fracturing stage block is assumed to be a mean in-situ stress model, that is, the in-situ stress at each cluster position within the stage is equal. This is acceptable for a rough assessment of the formation in-situ stress. However, since this patent involves the detailed calculation of the number of perforations in each cluster, it is necessary to accurately calculate the in-situ stress distribution within the stage. In addition, the presence of horizontal wellbores and perforations in the reservoir will cause local stress concentration, resulting in a change in the in-situ stress at the fracture initiation point near the perforations. It is necessary to calculate the fluid pressure required for reservoir fracture according to the in-situ stress redistribution model. Therefore, the process of calculating the fluid pressure required for reservoir fracture to overcome the in-situ stress includes first describing the in-situ stress distribution within the stage based on well logging data and the block in-situ stress field model, then calculating the initiation point stress according to the in-situ stress redistribution model, and finally solving the model to obtain the required fluid pressure. The expression of the fluid pressure calculation model is:

[0165]

[0166] In the formula, σ H,i , σ h,i , σ v,i are the maximum horizontal principal stress, minimum horizontal principal stress and vertical stress of the reservoir obtained based on the geomechanics model, Pa; τ xy,i is the reservoir plane shear stress, Pa; σ s is the tensile strength of the reservoir rock, Pa; θ and θ′ are the perforation phase angle and perforation initiation angle respectively, dimensionless.

[0167] The expression of the target wellbore friction calculation model along the well path is:

[0168]

[0169]

[0170]

[0171] In the formula, C cf is the wellbore friction coefficient, Pa·s / m 3 ; l j is the distance from the jth cluster of fractures to the wellbore heel, m; q w,j , q T are the fluid injection flow rate of the jth cluster of fractures and the total wellbore flow rate respectively, m 3 / s; K is the fracturing fluid consistency coefficient, Pa·s n′ ; n′ is the flow behavior index, dimensionless.

[0172] The induced stress p id,i is calculated according to the displacement discontinuity method. The fracture aperture parameter used in the model needs to refer to the old well fracturing simulation results. The expression of the initiation point induced stress calculation model is:

[0173] pid,i = A ns D s + A nn D n

[0174]

[0175] where A ns and A nn are boundary stress influence coefficients, Pa / m; D n and D s are normal and tangential displacement components, m; G is the shear modulus of the rock, GPa; x and y are the coordinates of any point within the target area, m; a is the length of the fracture element, m; γ is the fracture extension angle; v is the Poisson's ratio of the reservoir rock, dimensionless.

[0176] The expression of the perforation friction calculation model is:

[0177]

[0178] where ρ s is the density of the fracturing fluid, kg / m 3 ; n f,i is the number of perforations in the i-th cluster, dimensionless; d f,i is the perforation diameter, mm; C d is the perforation friction coefficient, dimensionless.

[0179] To make the liquid intake resistance of each cluster the same, then:

[0180] p a,1 = p a,2 = p a,i = p a,n

[0181] The above conditions can be achieved by adjusting the perforation friction of each cluster. Solve using the iterative method. Referring to the perforation number of the surrounding old wells, the perforation number of the fracture cluster closest to the wellbore heel can be fixed first, and then based on this, gradually increase the perforation number to obtain the perforation numbers of other clusters until all the perforation numbers of all clusters within the section are solved.

[0182] (3) Fracture propagation simulation and optimization of fracturing construction parameters

[0183] Based on the dynamic in-situ stress field model considering formation pressure depletion, apply commercial fracturing design software such as Gohfer and Petrel to simulate the fracturing fracture propagation of infill wells. Simulate and analyze the fracture propagation law of infill wells under different construction displacement and scale conditions, compare the fracture morphology differences between infill wells and old wells, and judge the risk of fracture connectivity between the two.

[0184] Taking the half fracture length of the infill well as 80% - 90% of the difference between the well spacing and the half fracture length of the existing well, and based on the existing well fracturing design parameters, including liquid volume, sand volume, displacement, sand addition mode, temporary plugging mode, etc., use the calculation method given in step (2) to calculate the number of perforations for each cluster in the fracture section. According to the sequence of fracturing construction parameters such as fracturing fluid viscosity, liquid volume, displacement, etc., set the change interval and gradually reduce the parameter values to simulate the fracture morphology, bottom hole pressure, proppant placement state and other data under different construction parameter conditions, and select the most suitable fracturing construction parameter combination close to the design target from them.

[0185] (4) Perforation operation and acid pre-treatment operation

[0186] For the perforation operation of the fracture section, use the spiral perforation method, the perforation phase angle is 60°, the perforating gun is 20 holes / m, and adjust the length of the perforating gun according to the number of perforations in each cluster. The first section uses the coiled tubing perforation operation technology, and from the second section to the last section, use the bridge plug perforation combination technology.

[0187] The acid usually used in on-site construction is 15% hydrochloric acid. The acid consumption in the first section is set at 40m 3 , and for other sections, set the acid consumption at 15 - 30m according to the distribution of minerals such as calcite and shale and the distribution of drilling fluid leakage points. 3 . For the acid injection process parameters, the displacement is 1.5 - 2.0m 3 / min. After the acid injection is completed, increase the displacement to 4m 3 / min to promote the uniform acid intake of each perforation cluster.

[0188] (5) Fracture creation and sand addition operation

[0189] Use the parameters such as the amount of gel fluid, construction displacement, sand addition timing, sand addition type and sand ratio optimized in step (3) for the preliminary fracturing construction. Use the stepwise increase in displacement method to increase the displacement to the highest stage. This can ensure that the fracturing fluid in the low displacement stage when the construction pressure is low mainly enters the perforation clusters on the side of the low in-situ stress. After increasing the displacement, it is beneficial to form a dominant channel for fractures in the area on this side of the wellbore.

[0190] For the stepwise increase in displacement, a step can be set every 3.0 - 4.0m 3 / min, and each step stays for 3.0 - 8.0min. When the displacement is increased to about 80% of the optimized design maximum displacement, stop increasing the displacement and start the main fracturing construction.

[0191] (6) Small particle size temporary plugging agent addition operation

[0192] The operation at this stage is to plug the dominant channels at the crack ends, promote crack diversion, and meet the requirements of complex fracture creation. Since the fracturing transformation sequence is from the low in-situ stress area to the high in-situ stress area, small-sized temporary plugging agents need to be added twice at 30% and 80% of the total construction fluid volume within a single stage. According to the optimized design content in step (3), 20 / 80 mesh temporary plugging agents are used, with a single dosage of 150 - 200 kg and an addition time of 180 - 240 s. After the temporary plugging agent arrives, observe the changes in the construction pressure rise and the microseismic monitoring event points. If the increase in the construction pressure exceeds the average level of the construction pressure rise during the temporary plugging of the old wells in the surrounding area, or there are obvious new microseismic event points on the low in-situ stress side of the wellbore, it is considered that the current temporary plugging mode has good adaptability. If the temporary plugging requirements are not met, for the subsequent fracturing stage construction, optimize the temporary plugging mode in the order of increasing the temporary plugging agent by 50 kg each time and then shortening the addition time by 15 - 30 s. Generally, based on the initial temporary plugging mode, optimizing 1 - 3 times can meet the temporary plugging requirements.

[0193] (7) Large-sized temporary plugging agent addition operation

[0194] After the large-sized temporary plugging agent enters the formation, it aggregates into lumps and will preferentially enter the dominant fracture channels with larger fracture widths. Since it is difficult to migrate towards the crack ends, it will mainly accumulate near the crack mouth, which can play a role in reducing the liquid inflow rate of the dominant fracture channels, thereby increasing the liquid inflow rate of the fractures on the high in-situ stress side of the wellbore. The addition timing of the large-sized temporary plugging agent is set at 60% of the total construction fluid volume. 10 / 40 mesh temporary plugging agents are used, with a single dosage of 50 - 100 kg and an addition time of 120 - 180 s. After the temporary plugging agent arrives, observe whether the increase in the construction pressure exceeds 3.0 MPa, and whether there is an obvious increase in the construction pressure step after temporary plugging compared to before temporary plugging. If so, it is considered that the temporary plugging requirements are met. If not, for the subsequent fracturing stage, optimize the temporary plugging method by increasing the 20 / 80 mesh temporary plugging agent by 25 - 50 kg each time. The small-sized temporary plugging agent and the large-sized temporary plugging agent are easier to aggregate into lumps and have a stronger ability to plug the crack mouth.

[0195] (8) Low-viscosity slickwater carrying proppant construction operation

[0196] For the fracturing of infill wells, it is necessary to avoid the connection between the fractures and the fractures of the surrounding old wells, otherwise it will have a greater negative impact on the productivity of the old wells. Under the condition of maintaining a certain level of liquid usage intensity and sand addition intensity, low-viscosity slickwater fracturing construction is used, which can not only control the fracture length but also help improve the complexity of fracture creation. The fracturing fluid dosage is based on the optimized design results in step (3), and the proportions of low-viscosity, medium-viscosity, and high-viscosity slickwater are set according to the fracturing parameters of the surrounding old wells. On this basis, gradually reduce the usage of medium-viscosity and high-viscosity slickwater and increase the usage of low-viscosity slickwater, which can be reduced by 50 - 100 m per stage 3Carry out at a certain rate and observe the change of the construction pressure curve. If the construction pressure curve shows a rapid increase, the sand addition can be stopped, and measures such as increasing the middle-top glue solution can be taken to promote the migration of proppants in the fracture to the far wellbore, so as to make the construction pressure curve return to stability.

[0197] The sand addition method is mainly in the form of slugs. Adjust the length of the sand addition slug according to the change of the construction pressure. When the fracturing fluid is low-viscosity slickwater, appropriately reduce the length of the sand addition slug. The overall sand ratio of the sand addition refers to the fracturing parameters of the surrounding old wells. Before the first addition of small-particle temporary plugging agents, the sand ratio of the sand addition does not exceed 70% of the highest sand ratio to avoid excessive sand settlement near the wellbore, resulting in a too rapid increase in the construction pressure.

[0198] (9) Displacement operation

[0199] After completing the designed sand addition amount in step (8), design the displacement fluid amount according to 110% - 120% of the wellbore volume. Among them, 40% - 50% of the displacement fluid amount uses high-viscosity slickwater to sweep the wellbore to prevent sand settlement in the wellbore, and the remaining displacement fluid amount is low-viscosity slickwater.

[0200] (10) Fracturing construction of the remaining sections

[0201] Repeat the process of steps (4) - (9) for the construction of the remaining sections until the construction of all fracturing sections is completed.

[0202] This embodiment relates to a new technology for fracturing shale gas infill wells. The overall idea of this embodiment is:

[0203] (1) Geological-engineering integrated fracturing design technology

[0204] On the basis of fully excavating the geological data and engineering data of the target area, carrying out geological-engineering integrated modeling and process optimization is the basis for the fracturing design of old wells and infill wells.

[0205] Carry out fracturing design according to the idea of guiding engineering practice with geological understanding and deepening geological understanding through engineering practice. First, establish a geological model of the target block based on data such as seismic, logging, mud logging, and core observation, and finely depict the geological structure, sweet spot distribution, reservoir physical property parameters, rock mechanics parameters, fault and natural fracture distribution and other attribute characteristics of the block. Then, take the full utilization of geological sweet spots and the balanced transformation of the whole well section as the goal to conduct numerical simulation of fracture propagation and optimization design of fracturing parameters, obtain the optimal construction parameter combination, and fit according to the actual pumping program, fracturing construction curve, fracturing construction parameters and microseismic monitoring results. On this basis, correct the initial geological model parameters, among which the adjustment accuracy of key geological parameters such as porosity and permeability should be within 10%. After that, conduct history matching according to the production system of the fractured well, bottom hole / wellhead pressure monitoring data and production data during the production cycle to accurately simulate the formation pressure change characteristics around the fractured well, and then use the finite element method to conduct dynamic coupling numerical simulation of in-situ stress-formation pressure to analyze the evolution law of the four-dimensional in-situ stress field. Finally, based on the corrected geological model, carry out fracturing design for infill wells, while avoiding well interference and maximizing the effective utilization of reserves in the uninvaded area.

[0206] Among them, the key fracturing technologies for infill wells are as follows.

[0207] (2) Adopt the limited-entry perforation technology

[0208] The key to achieving balanced initiation of multiple clusters of perforations within a section is that the fracture pressure of the reservoir rocks in each cluster is equal. Accurately predict the fracture pressure through the geological model, and innovatively establish a resistance model for fracture initiation and propagation, providing a basis for optimizing the limited-entry perforation parameters.

[0209] The initiation and propagation resistance of intra-stage fractures includes the in-situ stress at the location of each cluster, fracture friction, and the induced stress generated by the previously fractured stage. The differences in these three types of resistance are also the direct cause of the unbalanced propagation of fractures. Since the in-situ stress and induced stress cannot be effectively changed, the equality of the fracture resistance of each cluster can only be achieved by changing the fracture friction. The in-situ stress can be obtained through a geomechanical model, and the induced stress can be obtained according to the induced stress calculation model. First, the net fracture pressure of the previous fractured stage is fitted using commercial fracturing software, and then the additional induced stress field at the location of the current fractured stage is quantitatively described using the induced stress field calculation model based on the displacement discontinuity method. The fracture friction includes wellbore friction and perforation friction. In the field, the perforation friction of each cluster is usually changed by changing the number of perforations to balance the difference between the in-situ stress field and the induced stress field, and finally, the initiation and propagation resistance of each cluster of fractures are made the same. First, calculate the friction of each cluster based on the wellbore friction model and the perforation friction model, and then use the superposition method to calculate the fracture resistance of each cluster. The number of perforations for each cluster is calculated using the iteration method. Taking the number of perforations as the independent variable, calculate the initiation and extension resistance of each cluster of fractures, and judge whether they are all equal. If not, change the number of perforations per unit until the initiation and extension resistance of each cluster of fractures are equal, and obtain the final number of perforations for each cluster.

[0210] The use of limited-entry perforation technology can solve the problem of unbalanced initiation and propagation of fractures between clusters in advance, reduce unnecessary technological measures during construction, and thus more targeted solve the problem of asymmetric propagation of intra-cluster fractures and improve the fracturing treatment effect.

[0211] (3) Draw on the fracturing process parameters of old wells

[0212] For the fracturing process parameters of infill wells, in addition to optimizing the parameters using commercial fracturing design software, it is more important to fully draw on the fracturing process parameters of the already fractured wells based on the "proximity principle", including: stage-cluster division mode, liquid injection intensity, sand addition intensity, construction displacement, microseismic monitoring results, etc. Then, according to parameters such as well spacing and single-well controlled area, use the fracturing design software to further optimize the sand volume and liquid volume to better control the fracture propagation range of infill wells and avoid cross-well interference. Usually, the fracturing scale of infill wells is not higher than that of old wells.

[0213] (4) Adopt the technology of multi-agent temporary plugging with temporary plugging agent

[0214] The difference in in-situ stress on both sides of infill wells will lead to asymmetric fracture propagation. The use of the temporary plugging method with temporary plugging agent in the middle changes the preferential fluid intake channel to achieve balanced fluid intake of fractures on both sides of the wellbore. Therefore, the functions of the temporary plugging agent mainly include two points. One is to block the preferential channel, causing the fracture to be pressured, increasing the net pressure in the fracture, promoting fracture diversion, and realizing complex fracture creation. The other is that the large-particle-size temporary plugging agent accumulates at the fracture opening, increasing the fluid intake resistance of the preferential channel within the cluster and increasing the fluid intake volume of the fracture on the other side within the cluster, promoting symmetric propagation of fractures on both sides of the wellbore.

[0215] During the fracturing process, the liquid intake resistance on the side with low in-situ stress on both sides of the wellbore is relatively small, and it is bound to form a preferential channel first. Moreover, the greater the in-situ stress difference on both sides of the wellbore, the more obvious the liquid intake preferential channel. Without using the temporary plugging technology during the process, when the in-situ stress difference on both sides of the wellbore is about 3.0 MPa, the half fracture length and fracture width in the high in-situ stress area are about 85% and 80% of those in the low in-situ stress area respectively, while when the stress difference on both sides reaches 5.0 MPa, the corresponding values become 70% and 60%. Therefore, due to the differences in the fracture geometric parameters on both sides of the wellbore, the flow direction of the fracturing fluid can be changed through the temporary plugging technology during the process to promote the balanced expansion of fractures, and the plugging degree of the temporary plugging agent can be controlled by optimizing parameters such as the particle size, dosage, and timing of the temporary plugging agent to achieve differential plugging.

[0216] Based on this, fracturing is carried out in the transformation sequence of the low in-situ stress area first and then the high in-situ stress area, and three times of temporary plugging agent temporary plugging are set. The first time, a small particle size temporary plugging agent of 20 / 80 mesh is used at 30% of the liquid intake volume. The temporary plugging agent will mainly concentrate on the side with low in-situ stress, and the complex fracture formation in this area is carried out first. The second time, a large particle size temporary plugging agent of 10 / 40 mesh is used at 60% of the liquid intake volume. Due to its large particle size, after agglomerating into blocks, it will accumulate at the fracture mouth of the liquid intake preferential channel, increasing the liquid intake resistance and prompting the fracturing fluid to flow to the non-preferential channel on the other side of the wellbore to achieve the fracturing transformation of the high in-situ stress area. The third time, a small particle size temporary plugging of 20 / 80 mesh is used again at 80% of the liquid intake volume, and its main function is to achieve the complex fracture formation in the high stress area.

[0217] The method of combining numerical simulation and on-site tests is used to optimize the dosage and timing of the temporary plugging agent. Since the fracturing transformation is carried out in the partition sequence, controlling the flow direction of the temporary plugging agent to the predetermined area is the key to achieving balanced transformation. First, according to the numerical simulation results of fracture propagation by commercial software, the change range of the fracture width at each stage of single-stage fracturing is determined. The type of temporary plugging agent is matched according to the ratio of the fracture width to the particle size of the temporary plugging agent of about 2.5 - 3.5. The initial use of the small particle size temporary plugging agent is 150 - 200 kg, and the initial use of the large particle size temporary plugging agent is 50 - 100 kg. Then, according to the rising amplitude of the construction pressure curve, the change of microseismic event points, and the G function analysis, the differences in the fracture geometric parameters on both sides of the wellbore are compared to judge the temporary plugging effect. If the difference is not within the set range, the temporary plugging technology during the process is optimized in the order of adjusting the temporary plugging timing first, then increasing the dosage of the temporary plugging agent, and controlling the delivery time until the differences in the fracture parameters on both sides of the wellbore obtained by inversion are within the set range.

[0218] (5) Reduce the viscosity of the fracturing fluid

[0219] According to relevant research, under the condition of the same construction scale, taking the fracturing fluid viscosity of 10 mPa·s as an example, within a certain range, when the viscosity is reduced by 10% each time, the microseismic monitoring fracture length decreases by 5% - 7%, and the fracture complexity increases by about 6% - 7%. That is, reducing the viscosity of the fracturing fluid can reduce the fracture length and increase the fracture complexity.

[0220] For the fracturing transformation of infill wells, preventing the connection of fractures between wells is an important task. Once the fractures of the infill wells communicate with those of the old wells, the formation pressure is relieved, the productivity of the old wells will decrease significantly, and it is difficult to recover. Moreover, after the old wells have been producing for some time, the gas content in the reservoir around the infill wells gradually decreases. Therefore, the main goal of the fracturing transformation of infill wells is to control the scale of fracture extension and improve the complexity of fracture formation. By appropriately reducing the viscosity of the fracturing fluid, the fracture extension ability in the fracture length direction can be reduced, the ability to penetrate microfractures can be improved, and the opening of more branched fractures can be promoted. First, simulate the fracture length of the main construction of the old well with the viscosity of the fracturing fluid, and then gradually reduce the viscosity of the fracturing fluid by 5% - 10% proportionally, and numerically calculate the fracture geometric parameters until the target design requirements are met.

[0221] Example 4

[0222] In this example, the distance between two old wells in a shale gas block in the Sichuan Basin, China is 630 m. The wells have been in production for 5.5 years. An infill well X is arranged in the middle of the two old wells. The depth of well X is 2,630.00 m, and the length of the horizontal section is 2,170.00 m. Taking the fracturing of this well as an example, the present invention is further explained, and a new method for improving the symmetry of the fracturing fractures of shale gas infill wells is provided, including:

[0223] 1) Optimization of fracturing parameters for infill wells. Based on conventional well logging data, mud logging data, core experiment data, and data of surrounding adjacent wells, etc., carry out reservoir evaluation research to obtain key parameters of reservoir physical properties and rock mechanical properties for the targeted fracturing design of infill wells. Use the productivity simulation model of old wells to simulate the change of formation pressure around the infill wells, and then combine with the original geomechanical model to establish a dynamic change model of the in-situ stress field, simulate the distribution of the in-situ stress field around the infill wells today, and compare the differences in the three-dimensional in-situ stress fields on both sides of the wellbore. As Figure 2 shown in the figure is the change of the minimum horizontal principal stress magnitude in the cross-cutting direction of the infill well. The in-situ stress on the right side of the wellbore is about 5.2 - 7.5 MPa higher than that on the left side.

[0224] 2) Apply the mature fracturing optimization design software Gohfer to simulate the fracture propagation morphology under different construction parameters such as liquid volume, sand volume, and displacement, and optimize to obtain 7 - 8 clusters per section, with a cluster spacing of 7 - 10 m, 1,700.0 m of fracturing fluid 3 , 74 m of sand volume 3 , a construction displacement of 13.0 - 15.0 m 3 / min, and the viscosity of low-viscosity slickwater is 6.0 - 9.0 mPa·s.

[0225] 3) Perforation quantity calculation and perforation operation. The spiral perforation method is adopted with a perforation phase angle of 60°. To ensure balanced fluid intake for each cluster, according to the fracture fluid intake resistance calculation method described in step 3, the perforation quantity for each cluster is calculated. Then, combined with the actual perforating gun length classification, the optimized perforation quantity for each cluster from the end to the heel of the self-fracturing section is 6, 5, 5, 4, 4, 4, 3, 3, and the aperture is 12 mm.

[0226] 4) Acid pre-treatment operation, injecting 20.0 m of 15% hydrochloric acid for each section 3 , with a displacement of 2.0 m 3 / min. After the acid liquid injection is completed, it is displaced with low-viscosity slickwater, and the displacement is increased to 4.0 m 3 / min to ensure uniform acid quantity for each cluster.

[0227] 5) Prepad fluid fracture creating and sand addition construction, with 80 m of prepad fluid 3 , and the displacement is increased stepwise from 4.0 m 3 / min to 9.0 m 3 / min to 14.0 m 3 / min, and each step stays for 3.0 min. After the prepad fluid injection is completed, it is switched to high-viscosity fracturing fluid with a volume of 100.0 m 3 . During the process of switching to high-viscosity fracturing fluid, 70 / 140 mesh quartz sand is added, and the sand-to-fluid ratio is increased stepwise by 4% - 6% - 7% - 8%, and the volume for each sand-to-fluid ratio is 50.0 - 60.0 m 3 .

[0228] 6) Small particle size temporary plugging agent addition operation. When the injected fluid volume reaches 500.0 m 3 and 1350.0 m 3 , 150 kg of 20 / 80 mesh temporary plugging agent is added respectively, and the addition time is 200 s, and the construction displacement remains unchanged at the original displacement.

[0229] Large particle size temporary plugging agent addition operation. When the injected fluid volume reaches 1000 m 3 , 75 kg of 10 / 40 mesh temporary plugging agent is added, and the addition time is 150 s. After the temporary plugging agent enters the formation, the construction displacement is increased to 16.0 m 3 / min.

[0230] 7) Low-viscosity slickwater carrying proppant construction. After the high-viscosity slickwater injection in step 5 is completed, it is switched to low-viscosity slickwater. Before adding the large particle size temporary plugging agent, 70 / 140 mesh quartz sand and 40 / 70 mesh quartz sand are added successively, and the sand-to-fluid ratio is increased stepwise from 4% to 12%, with a single increase of 1% - 2%, and the injection volume for each sand-to-fluid ratio is 50.0 - 80.0 m 3 / min. After injecting the large-particle-size temporary plugging agent, 70 / 140 mesh quartz sand, 40 / 70 mesh quartz sand, and 40 / 70 mesh coated sand are added respectively. The sand-fluid ratio is gradually increased from 10% to 16% in steps of 1% - 2% each time, and the injection volume of each sand-fluid ratio is 50.0 - 60.0 m 3 .

[0231] 8) Displacement operation, with a displacement fluid volume of 45.0 m 3 , among which the first 20.0 m 3 is high-viscosity slickwater, and then it is changed to low-viscosity slickwater, with a displacement rate of 16.0 m 3 / min.

[0232] 9) The construction of the remaining section refers to Steps 3 - 8 to complete the construction task of this well.

[0233] Figure 2 shows the change of the in-situ stress field around two old wells after they have been producing for some time. It can be seen that the in-situ stress field around the infill wells is significantly asymmetric, and new pressure technology is required. Figure 3 is the construction curve graph obtained by using the method of the present invention.

[0234] Through the implementation of the present invention, the initial unobstructed flow rate of this well is increased by about 16% compared with the existing fracturing process, and a good fracturing effect is obtained, providing good ideas and practices for the fracturing transformation of similar wells in this block.

[0235] The above new method for improving the symmetry of fracturing cracks in shale gas infill wells belongs to the field of oil and gas exploitation and is applicable to shale gas reservoirs. It can solve the problem of asymmetric propagation of fracturing cracks in infill wells caused by non-uniform distribution of in-situ stress on both sides of the infill wellbore. By comprehensively applying technical means such as limited-entry perforation technology, multi-stage temporary plugging with temporary plugging agents, and low-viscosity slickwater sand-carrying operation, it can better achieve the balanced transformation of infill wells and increase the fracturing transformation volume. The present invention effectively improves the fracturing transformation effect of infill wells, and the optimization results can effectively guide the on-site fracturing construction to obtain the maximum economic benefits.

[0236] Example Five

[0237] In this embodiment, as Figure 4 shown, a device for improving crack symmetry is provided, including:

[0238] A data acquisition module 210 for acquiring drilling and completion fluid parameters, geological data, old well production parameters, and old well fracturing construction parameters;

[0239] A first model construction module 220 for constructing a crack initiation and propagation resistance model based on the drilling and completion fluid parameters, the geological data, the old well production parameters, and the old well fracturing construction parameters;

[0240] The perforation number solving module 230 is configured to iteratively solve the fracture initiation and propagation resistance model to obtain the perforation numbers of each cluster when the fracture initiation and extension resistances of each cluster are equal;

[0241] The design parameter determination module 240 is configured to use the old well fracturing construction parameters to obtain multiple fracturing design parameters for the infill wells;

[0242] The second model acquisition module 250 is configured to acquire the dynamic in-situ stress field model under the formation pressure depletion state;

[0243] The fracturing simulation module 260 is configured to use the perforation numbers of each cluster, based on the dynamic in-situ stress field model under the formation pressure depletion state, and successively simulate multiple fracturing simulation results of the infill wells according to multiple fracturing design parameters of the infill wells;

[0244] The parameter determination module 270 is configured to use multiple fracturing simulation results of the infill wells to obtain the optimized fracturing simulation result of the infill wells, and obtain the fracturing design parameters of the infill wells corresponding to the optimized fracturing simulation result of the infill wells, and determine them as the fracturing construction parameters of the infill wells.

[0245] In one embodiment, the first model construction module 220 includes:

[0246] Construct a fracture initiation point stress model according to the in-situ stress dynamic change model;

[0247] Solve the fracture initiation point stress model to obtain a fluid pressure calculation model;

[0248] Establish an old well fracture propagation model according to the old well fracturing construction parameters to obtain an old well fracturing fracture simulation result;

[0249] Establish a fracture initiation point induced stress field model according to the old well fracturing fracture simulation result;

[0250] Obtain wellbore parameters and fracturing fluid performance parameters;

[0251] Based on the wellbore parameters and the fracturing fluid performance data, use the fluid mechanics method to construct a target wellbore frictional resistance calculation model along the wellbore;

[0252] Obtain perforation parameters;

[0253] Use the perforation parameters and the fracturing fluid performance parameters to construct a perforation frictional resistance calculation model;

[0254] Use the fluid pressure calculation model, the frictional resistance calculation model along the wellbore, the fracture initiation point induced stress calculation model, and the perforation frictional resistance calculation model to construct the fracture initiation and propagation resistance model.

[0255] In this embodiment, the drilling and completion fluid parameters include perforation parameters, wellbore parameters, and fracturing fluid performance parameters.

[0256] In one embodiment, the perforation number solving module 230 includes:

[0257] Set the initial value of the perforation number for each cluster in the perforation friction calculation model, and make the initial values of the perforation numbers for each cluster consistent;

[0258] Adjust the perforation number for each cluster in the perforation friction calculation model one by one until the fracture initiation and propagation resistances for each cluster are equal to determine the perforation number for each cluster.

[0259] For the specific limitations on the device for improving fracture symmetry, reference can be made to the limitations on the method for improving fracture symmetry in the above text, which will not be elaborated here. Each unit in the above device for improving fracture symmetry can be implemented in whole or in part by software, hardware, and their combination. The above units can be embedded in the processor of the computer device in hardware form or independent of it, or stored in the memory of the computer device in software form so that the processor can call and execute the operations corresponding to the above units.

[0260] Embodiment Six

[0261] In this embodiment, a computer device is provided. Its internal structure diagram can be as Figure 5 shown. The computer device includes a processor, a memory, a network interface, a display screen, and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program, and a database is deployed on the non-volatile storage medium. The database is used for old well fracturing fracture parameters, logging data, wellbore parameters, fracturing fluid performance parameters, and perforation parameters. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with other computer devices on which application software is deployed. When the computer program is executed by the processor, it implements a method for improving fracture symmetry. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device can be a touch layer covering the display screen, or a button, a trackball, or a touchpad provided on the housing of the computer device, or an external keyboard, a touchpad, or a mouse, etc.

[0262] Those skilled in the art can understand, Figure 5The structure shown is only a block diagram of some of the structures related to the solution of this application, and does not constitute a limitation on the computer device to which the solution of this application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different component arrangement.

[0263] In one embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the steps of the method for improving crack symmetry described in any of the above embodiments.

[0264] Embodiment Seven

[0265] In this embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, it implements the steps of the method for improving crack symmetry described in any of the above embodiments.

[0266] Those of ordinary skill in the art can understand that all or part of the processes of implementing the methods in the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to the memory, storage, database, or other media used in the various embodiments provided in this application can include non-volatile and / or volatile memories. Non-volatile memories can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memories can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0267] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0268] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method for improving crack symmetry, characterized in that, Including: Obtaining drilling and completion fluid parameters, geological data, production parameters of old wells, and fracturing construction parameters of old wells; Based on the drilling and completion fluid parameters, the geological data, the production parameters of old wells, and the fracturing construction parameters of old wells, constructing a fracture initiation and propagation resistance model; Performing iterative solution on the fracture initiation and propagation resistance model to obtain the number of perforations for each cluster when the fracture initiation and extension resistances of each cluster are equal; Using the fracturing construction parameters of old wells to obtain multiple fracturing design parameters for infill wells; Obtaining a dynamic in-situ stress field model under the formation pressure deficit state; Using the number of perforations for each cluster, based on the dynamic in-situ stress field model under the formation pressure deficit state, and according to multiple fracturing design parameters for infill wells, successively simulating multiple fracturing simulation results for infill wells; Using multiple fracturing simulation results for infill wells to obtain an optimized fracturing simulation result for an infill well, and obtaining the fracturing design parameters for the infill well corresponding to the optimized fracturing simulation result for the infill well, and determining them as the fracturing construction parameters for the infill well.

2. The method according to claim 1, wherein The drilling and completion fluid parameters include perforation parameters, wellbore parameters, and fracturing fluid performance parameters; The step of constructing a fracture initiation and propagation resistance model based on the drilling and completion fluid parameters, the geological data, the production parameters of old wells, and the fracturing construction parameters of old wells includes: Constructing an initiation point stress model according to the in-situ stress dynamic change model; Performing solution on the initiation point stress model to obtain a fluid pressure calculation model; According to the fracturing construction parameters of old wells, establishing an old well fracture propagation model to obtain an old well fracturing fracture simulation result; According to the old well fracturing fracture simulation result, establishing an initiation point induced stress field model; Obtaining wellbore parameters and fracturing fluid performance parameters; Based on the wellbore parameters and the fracturing fluid performance data, using the fluid mechanics method to construct a target wellbore along-the-way friction resistance calculation model; Obtaining perforation parameters; Using the perforation parameters and the fracturing fluid performance parameters to construct a perforation friction resistance calculation model; Using the fluid pressure calculation model, the along-the-way friction resistance calculation model, the initiation point induced stress calculation model, and the perforation friction resistance calculation model to construct the fracture initiation and propagation resistance model.

3. The method according to claim 2, wherein The step of performing iterative solution on the fracture initiation and propagation resistance model to obtain the number of perforations for each cluster when the fracture initiation and extension resistances of each cluster are equal includes: Setting an initial value for the number of perforations for each cluster in the perforation friction resistance calculation model, and making the initial values of the number of perforations for each cluster consistent; Adjusting one by one the number of perforations for each cluster in the perforation friction resistance calculation model until the fracture initiation and propagation resistances of each cluster are equal to determine the number of perforations for each cluster.

4. A process for improving crack symmetry, characterized in that, Including: Adopting the method described in any one of claims 1 to 3 to determine the fracturing construction parameters for the infill well and the number of perforations for each cluster in the fracturing section; Using the determination of the fracturing construction parameters for the infill well and the number of perforations for each cluster in the fracturing section to perform the following steps: 1) Performing perforation operations according to the number of perforations for each cluster in the fracturing section; 2) Acid pretreatment operations; 3) According to the fracturing construction parameters of the infill well, during the fracture creating operation and the proppant adding operation, successively conduct the small-particle-size temporary plugging agent adding operation, the large-particle-size temporary plugging agent adding operation, and the low-viscosity slickwater carrying proppant construction operation; 4) According to the fracturing construction parameters of the infill well, conduct the displacement operation; Repeat the above steps 1) to 4) until the construction of all fracturing sections of the infill well is completed.

5. The process according to claim 4, characterized in that, The fracturing construction parameters of the infill well include the perforating gun length; Determine the perforating gun length by using the number of perforations in each cluster within the fracturing section; Conduct the perforating operation by using the perforating gun with the perforating gun length.

6. The process according to claim 4, characterized in that, The fracturing construction parameters of the infill well further include the preset addition times and the preset addition time of the small-particle-size temporary plugging agent; The steps of the small-particle-size temporary plugging agent adding operation include: Conduct the first small-particle-size temporary plugging agent adding operation according to the preset addition times and the preset addition time of the small-particle-size temporary plugging agent; Observe the changes in the construction pressure rise and the changes in the microseismic monitoring event points to judge the adaptability of the temporary plugging mode of the first small-particle-size temporary plugging agent adding operation; When the adaptability of the temporary plugging mode of the first small-particle-size temporary plugging agent adding operation meets the temporary plugging requirements of the first small-particle-size temporary plugging agent adding operation, conduct the subsequent small-particle-size temporary plugging agent adding operations according to the preset addition times and the preset addition time of the small-particle-size temporary plugging agent; When the adaptability of the temporary plugging mode of the first small-particle-size temporary plugging agent adding operation is lower than the temporary plugging requirements of the first small-particle-size temporary plugging agent adding operation, adjust the preset addition times and the preset addition time of the small-particle-size temporary plugging agent, determine the optimized preset addition times and the optimized preset addition time of the small-particle-size temporary plugging agent, and conduct the subsequent small-particle-size temporary plugging agent adding operations according to the optimized preset addition times and the optimized preset addition time of the small-particle-size temporary plugging agent.

7. The process according to claim 4, characterized in that, The fracturing construction parameters of the infill well further include the preset addition times and the preset addition time of the large-particle-size temporary plugging agent; The steps of the large-particle-size temporary plugging agent adding operation include: Conduct the first large-particle-size temporary plugging agent adding operation according to the preset addition times and the preset addition time of the large-particle-size temporary plugging agent; Observe the changes in the construction pressure rise and the changes in the microseismic monitoring event points to judge the adaptability of the temporary plugging mode of the first large-particle-size temporary plugging agent adding operation; When the adaptability of the temporary plugging mode of the first large-particle-size temporary plugging agent adding operation meets the temporary plugging requirements of the first large-particle-size temporary plugging agent adding operation, conduct the subsequent large-particle-size temporary plugging agent adding operations according to the preset addition times and the preset addition time of the large-particle-size temporary plugging agent; When the adaptability of the temporary plugging mode of the first large-particle-size temporary plugging agent adding operation is lower than the temporary plugging requirements of the first large-particle-size temporary plugging agent adding operation, adjust the preset addition times and the preset addition time of the large-particle-size temporary plugging agent, determine the optimized preset addition times and the optimized preset addition time of the large-particle-size temporary plugging agent, and conduct the subsequent large-particle-size temporary plugging agent adding operations according to the optimized preset addition times and the optimized preset addition time of the large-particle-size temporary plugging agent.

8. A device for improving crack symmetry, characterized in that, Include: A data acquisition module, configured to acquire drilling and completion fluid parameters, geological data, old well production parameters, and old well fracturing construction parameters; The first model construction module is used to construct a fracture initiation and propagation resistance model based on the drilling and completion fluid parameters, the geological data, the production parameters of the old well, and the fracturing construction parameters of the old well; The perforation number solving module is used to perform iterative solution on the fracture initiation and propagation resistance model to obtain the perforation numbers of each cluster when the fracture initiation and extension resistances of each cluster are equal; The design parameter determination module is used to obtain multiple fracturing design parameters for the infill wells by using the fracturing construction parameters of the old well; The second model acquisition module is used to acquire a dynamic in-situ stress field model under the formation pressure depletion state; The fracturing simulation module is used to use the perforation numbers of each cluster, based on the dynamic in-situ stress field model under the formation pressure depletion state, and successively simulate multiple fracturing simulation results of the infill wells according to multiple fracturing design parameters for the infill wells; The parameter determination module is used to use the multiple fracturing simulation results of the infill wells to obtain an optimized fracturing simulation result of the infill wells, and obtain the fracturing design parameters of the infill wells corresponding to the optimized fracturing simulation result of the infill wells, and determine them as the fracturing construction parameters of the infill wells.

9. A computer device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, the steps of the method according to any one of claims 1 to 3 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, the steps of the method according to any one of claims 1 to 3 are implemented.

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