A fracture parameter design method, device and machine readable storage medium

Abstract

The application provides a fracture parameter design method, device and machine readable storage medium, wherein the method calculates fracture parameters by establishing a three-dimensional geomechanical model of a target well to obtain a fracture parameter evaluation group; and further constructs a single-fracture fracture productivity model according to the fracture parameters in the fracture parameter evaluation group; finally, the fracture parameters are optimized according to the single-fracture fracture productivity model; the method effectively optimizes and designs the fracture parameters for the target well, designs the fracture parameters based on the three-dimensional geomechanical model by combining fracture expansion and productivity prediction, finally obtains the optimized fracture parameters for the horizontal well reconstruction, and can effectively ensure the effect of the fracture reconstruction. The fracture parameter design device and the machine readable storage medium of the application are both based on the fracture parameter design method of the application and have the same beneficial effects.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas exploration in discontinuous tight sandstone reservoirs, and specifically relates to a fracture parameter design method, device and machine-readable storage medium. Background Technology

[0002] In recent years, the proportion of exploration and development of tight sandstone reservoirs has been increasing year by year. Tight sandstone reservoirs have low matrix permeability, so they must be stimulated by fracturing with proppant. However, tight sandstone reservoirs often have strong inter-section heterogeneity and are often discontinuously distributed. Using uniform fracture design parameters for a single well often fails to achieve sufficient stimulation.

[0003] Current technologies typically combine production capacity prediction results with fracture parameter design. The range of the evaluated fracture parameters is often derived from experience, failing to couple production capacity prediction with fracture propagation prediction. Therefore, it is necessary to research a method for designing artificial fracture parameters in horizontal wells suitable for discontinuous tight sandstone reservoirs. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a fracture parameter design method, apparatus, and machine-readable storage medium, capable of designing fracture parameters for a single well.

[0005] The present invention provides a fracture parameter design method for determining fracture parameters in horizontal wells of discontinuous tight sandstone reservoirs, comprising the following steps:

[0006] Based on the reservoir parameters, seismic parameters, and well logging parameters obtained for the target area where the reservoir is located, a geomechanical model of the target area is constructed.

[0007] A three-dimensional geomechanical model of the target well is constructed based on the geomechanical model of the target area and the parameter data of the target well.

[0008] The fracture parameters are calculated based on the three-dimensional geomechanical model of the target well, a fracture parameter evaluation group is obtained, and a single fracture productivity model is constructed based on the fracture parameters in the fracture parameter evaluation group.

[0009] The crack parameters are optimized based on the single-crack productivity model.

[0010] Furthermore, prior to the step of calculating fracture parameters based on the three-dimensional geomechanical model of the target well, the method further includes the following step:

[0011] The target area is divided according to the principle of similar lithological and reservoir physical property parameters;

[0012] A seepage model is established for the low-permeability layer in the divided target area, and the seepage shielding zone is identified based on the seepage model;

[0013] The seepage shielding zone is determined based on the area ratio of the unused portion and the degree of utilization on both sides of the interface.

[0014] Furthermore, the process of constructing a three-dimensional geomechanical model of the target well based on the geomechanical model of the target area and the parameter data of the target well includes:

[0015] Based on the identification results of the seepage shielding zone, the reservoir continuity type of the target area is determined, and the target well stimulation requirements are obtained;

[0016] Obtain reservoir parameters, seismic parameters, logging parameters, and drilling parameters of the target well;

[0017] After partially extracting the geomechanical model of the target area, the extracted model is corrected based on the reservoir parameters, seismic parameters, logging parameters, and drilling parameters of the target well to obtain the three-dimensional geomechanical model of the target well.

[0018] Furthermore, after obtaining the three-dimensional geomechanical model of the target well, the following steps are also included:

[0019] Based on the identification results of the seepage shielding zone, after isolating the seepage shielding zone, the reservoir of the target well is segmented.

[0020] Furthermore, the step of calculating fracture parameters based on the three-dimensional geomechanical model of the target well, obtaining a fracture parameter evaluation group, and constructing a single-fracture productivity model based on the fracture parameters in the fracture parameter evaluation group includes the following steps:

[0021] Historical construction parameters of the target well are collected, including: cluster spacing, fluid intensity, sand addition intensity, displacement, and proppant type.

[0022] Based on the collected historical construction parameters and the three-dimensional geomechanical model, the crack propagation law is simulated to obtain the value range of crack parameters, including crack length, crack width and crack height, and a crack parameter evaluation group is established.

[0023] Each set of fracture parameters in the fracture parameter evaluation group is input into the three-dimensional geomechanical model of the target well to construct the corresponding single-fracture productivity model.

[0024] Furthermore, the optimization of the fracture parameters based on the single-fracture productivity model includes the following steps:

[0025] A single-fracture capacity model is constructed, which includes a radial seepage sub-model at the fracture end, a linear seepage sub-model on both sides of the fracture, and a non-Darcy seepage model within the fracture.

[0026] Solve the single-crack production capacity model to obtain the single-crack production capacity;

[0027] The optimal crack parameters are obtained based on the single-crack production rate.

[0028] Furthermore, the radial seepage sub-model at the fracture end is as follows:

[0029]

[0030] The linear seepage sub-model on both sides of the crack is as follows:

[0031]

[0032] The non-Darcy flow sub-model within the fracture is as follows:

[0033]

[0034] Where h is the reservoir thickness, in meters; r e Provide the reservoir radius, m; r wfn R represents the distance (m) from the nth fracture grid to the wellbore. wf The fracture half-length is in meters (m); r is the distance from a point in the gas reservoir to the wellbore, in meters (m). wf The width of the crack is m; p gsc p is standard atmospheric pressure, MPa; p is formation supply pressure, MPa; p e The original reservoir pressure is given in MPa; p wfn The pressure of the nth crack mesh is MPa; T gsc Standard temperature (°C); T is reservoir temperature (°C); Z gsc k is the gas deviation factor. g For gas phase permeability, mD; k wfn Let mD be the permeability of the nth fracture grid; α be the stress sensitivity coefficient; b be the slippage effect coefficient; Q0 be the inflow rate at the fracture tip; Q n Q represents the flow rate within the crack mesh, where n is the crack mesh index, the crack opening mesh index is 1, and n ≥ 1; wfn denoted as , where is the inflow rate across the nth crack grid; μ is the liquid viscosity (mPa·s); β is the fluid turbulence coefficient; and τ is the starting pressure gradient (MPa / m).

[0035] Furthermore, the process of solving the single-crack productivity model to obtain the single-crack productivity includes:

[0036] Construct a matrix, where k wfn r wfn and p wfn Q is the input parameter for the single-seam production capacity model. wfn and Q n The output results of the single-seam production capacity model are as follows:

[0037]

[0038] Where, k wfn Let mD be the permeability of the nth crack grid; r be the permeability of the crack grid. wfn Let m be the distance from the nth fracture grid to the wellbore; p wfn Q is the pressure of the nth crack mesh, in MPa; wfn Q represents the inflow rate across the nth crack mesh. n denoted as the flow rate within the crack mesh, where n is the crack mesh index, the crack opening mesh index is 1, and n≥1;

[0039] Based on the single-slit productivity model, the flow models from the matrix to the fracture mesh and within the fracture mesh are determined as follows:

[0040]

[0041] Where h is the reservoir thickness, in meters; r e Provide the reservoir radius, in meters; R wf The fracture half-length is in meters (m); r is the distance from a point in the gas reservoir to the wellbore, in meters (m). wf The width of the crack is m; p gsc p is standard atmospheric pressure, MPa; p is formation supply pressure, MPa; p e T represents the original reservoir pressure, in MPa; gsc Standard temperature (°C); T is reservoir temperature (°C); Z gsc k is the gas deviation factor. g Where is the gas phase permeability, mD; α is the stress sensitivity coefficient; b is the slip effect coefficient; Q0 is the inflow rate at the fracture tip; Q n denoted as , where is the flow rate within the fracture mesh, n is the fracture mesh number (with the fracture opening having a mesh number of 1, n≥1); μ is the liquid viscosity (mPa·s); β is the fluid turbulence coefficient; and τ is the starting pressure gradient (MPa / m).

[0042] The flow model described above is solved using an iterative method from the end of the crack to the crack opening. The resulting crack opening mesh flow rate Q1 is the single-crack production rate.

[0043] Furthermore, the step of obtaining the optimal crack parameters based on the single-crack production includes:

[0044] Based on the single-seam production capacity model, the cumulative single-seam output within the preset production cycle is predicted;

[0045] The set of crack parameters corresponding to the single-crack production capacity model that maximizes cumulative output is determined as the optimal crack parameters.

[0046] The present invention also discloses a crack parameter design device, comprising:

[0047] The regional geomechanical model construction unit is used to construct a geomechanical model of the target area based on the obtained reservoir parameters, seismic parameters, and well logging parameters of the target area where the reservoir is located.

[0048] The target well three-dimensional geomechanical model construction unit is used to construct a three-dimensional geomechanical model of the target well based on the target area geomechanical model and the parameter data of the target well.

[0049] The single-fracture productivity model construction unit is used to calculate fracture parameters based on the three-dimensional geomechanical model of the target well, obtain fracture parameter evaluation groups, and construct a single-fracture productivity model based on the fracture parameters.

[0050] An optimization unit is used to optimize the crack parameters based on the single-crack productivity model.

[0051] The present invention also discloses a machine-readable storage medium storing machine-readable program instructions, which are executed by a processor to perform the crack parameter design method of the present invention.

[0052] This invention discloses a fracture parameter design method that effectively optimizes fracture parameters for a target well. Based on a three-dimensional geomechanical model, it designs fracture parameters by combining fracture propagation and productivity prediction, ultimately obtaining the optimal fracture parameters for horizontal well stimulation, which effectively ensures the effectiveness of fracture stimulation. Specifically, it calculates fracture parameters by establishing a three-dimensional geomechanical model of the target well, thereby obtaining a fracture parameter evaluation group; further, it constructs a single-fracture productivity model based on the fracture parameters in the evaluation group; and finally, it optimizes the fracture parameters based on the single-fracture productivity model.

[0053] The crack parameter design apparatus and machine-readable storage medium of the present invention, based on the crack parameter design method of the present invention, have the same beneficial effects. Other features and advantages of the present invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention can be realized and obtained by means of the structures pointed out in the description, claims, and drawings. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 A flowchart illustrating the steps of a crack parameter design method according to an embodiment of the present invention is shown.

[0056] Figure 2 A simplified model of single-fracture seepage in a low-permeability gas reservoir according to an embodiment of the present invention is shown.

[0057] Figure 3 A schematic diagram illustrating the identification of the seepage shielding zone according to an embodiment of the present invention is shown. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] Considering that in existing technologies, for oil and gas reservoirs with discontinuous distribution and tight sandstone reservoir matrix, there is a problem that target well fracturing parameters need to be designed specifically to reduce fracturing costs and improve the target well stimulation effect, this application provides a method, device, and machine-readable storage medium for designing fracture parameters for discontinuous tight sandstone reservoirs. By constructing a three-dimensional geomechanical model of the target well, and comprehensively considering the simulation of fracture propagation and production prediction of the target well, the fracture parameters of the target well are optimized and designed to achieve targeted stimulation of heterogeneous tight sandstone reservoirs, reduce the cost of target well stimulation, and ensure the effectiveness of target well stimulation.

[0060] Example 1:

[0061] To facilitate understanding of this embodiment, a crack parameter design method disclosed in this application embodiment will first be described in detail. Figure 1 A flowchart of a crack parameter design method provided in an embodiment of this application is shown, as follows: Figure 1 As shown, it includes the following steps:

[0062] S101: Construct a geomechanical model of the target area based on the obtained reservoir parameters, seismic parameters, and well logging parameters of the target area where the reservoir is located;

[0063] Specifically, in the embodiments of this application, the parameters required to construct the geomechanical model of the target area include: triaxial principal stress, reservoir thickness, porosity, Poisson's ratio, horizontal well azimuth, well inclination angle, and basic parameters such as seismic and well logging data.

[0064] The geomechanical model of the target area refers to the geomechanical model of the large overall area where the discontinuous tight sandstone reservoir is located.

[0065] S102: Construct a three-dimensional geomechanical model of the target well based on the geomechanical model of the target area and the parameter data of the target well;

[0066] Specifically, in the embodiments of this application, a three-dimensional geomechanical model of the target well is constructed based on the geomechanical model of the target area and combined with the relevant parameter data of the target well (the area where it is located).

[0067] S103: Calculate fracture parameters based on the three-dimensional geomechanical model of the target well, obtain a fracture parameter evaluation group, and construct a single-fracture productivity model based on the fracture parameters in the fracture parameter evaluation group.

[0068] S104: Optimize the fracture parameters based on the single-fracture productivity model.

[0069] Specifically, in the embodiments of this application, after collecting basic parameters such as triaxial principal stress, reservoir thickness, porosity, Poisson's ratio, horizontal well azimuth, well inclination angle, and seismic and logging data, a seismic model is constructed based on regional seismic interpretation results. Systematic rock mechanics and geostress experiments are then conducted on different sand groups to calibrate the target well-seismic model. Using ant-body, likelihood body, and curvature body fracture characterization techniques, fracture distribution is accurately predicted, and a full-well geomechanical profile of the reservoir sandstone and interlayer mudstone is established. Finally, finite element geostress simulation technology is used to precisely construct the stress field of irregularly shaped geological bodies.

[0070] Furthermore, based on seismic and logging data from existing wells in the region, a three-dimensional geological model of the region is established, and the production history of the wells is used to fit and correct the model, thus building a platform for predicting the production capacity of target wells.

[0071] Specifically, in the embodiments of this application, the following step is included before step S103:

[0072] S1011: The target area is divided according to the principle of similar lithological and reservoir physical property parameters;

[0073] S1012: Establish a seepage model for the low-permeability layer in the divided target area, and identify the seepage shielding zone based on the seepage model;

[0074] The seepage shielding zone is determined based on the proportion of unused areas and the degree of utilization on both sides of the interface.

[0075] Specifically, in step S1011, the reservoir is first divided into reservoir segments and non-reservoir segments based on lithology, and the average physical property parameters are calculated for each segment of the non-reservoir segment.

[0076] Further subdivisions are made within the same lithological reservoir segment based on reservoir physical properties, and reservoirs are then classified according to their quality. The quality of the reservoir is related to the thickness of the inter-segment reservoirs within the sub-segments; for example, inter-segment reservoirs less than 5m in thickness can be classified as low-quality reservoirs.

[0077] Specifically, in step S1012, after combining the adjacent non-reservoir section with the low-quality reservoir into a low-permeability layer, a seepage model is established for the low-permeability layer; then, based on the reservoir utilization effect over three years of production, it is determined whether the low-permeability layer is a seepage shield zone.

[0078] Evaluation indicators for seepage shielding zones include the existence of large unused areas and the degree of difference in utilization on both sides of the seepage shielding zone interface. For example... Figure 3 The diagram illustrates the reservoir utilization effect over three years of simulation using a seepage model established for a low-permeability layer in a target well, according to a specific embodiment of the present invention. (a) shows a large-area utilization zone, indicating a non-seepage shielding zone; (b) shows a zone without a large-area utilization zone and with minimal difference in utilization on both sides of the interface, indicating a seepage shielding zone. It should be understood that those skilled in the art can set the thresholds for "large area" and "degree of difference" based on actual conditions.

[0079] Identifying the seepage shielding zone allows for accurate identification of reservoirs and low-permeability layers. During fracture parameter calculations, isolating the seepage shielding zone prevents it from being included in the modification scope, thereby saving modification costs and improving modification effectiveness.

[0080] Specifically, in the embodiments of this application, step S102 includes:

[0081] Based on the identification results of the seepage shielding zone, the reservoir continuity type of the target area is determined, and the target well stimulation requirements are obtained;

[0082] Obtain reservoir parameters, seismic parameters, logging parameters, and drilling parameters of the target well;

[0083] After partially extracting the geomechanical model of the target area, the extracted model is corrected and refined based on the reservoir parameters, seismic parameters, logging parameters and drilling parameters of the target well to obtain the three-dimensional geomechanical model of the target well.

[0084] Optionally, in the embodiments of this application, after constructing the geomechanical model of the target well (single well), and under the premise of isolating the seepage shielding zone, the reservoir is further segmented based on the seepage shielding zone identification results and reservoir physical property distribution characteristics. This segmented design enables targeted stimulation of heterogeneous tight sandstone reservoirs: stimulation is carried out on the non-seepage shielding zone. This segmented design takes into account that when performing fracture stimulation, it is not always possible to simultaneously stimulate the entire target well, thus determining the priority areas for stimulation through segmentation.

[0085] Specifically, in the embodiments of this application, step S103 includes:

[0086] Historical construction parameters of the target well are collected, including: cluster spacing, fluid intensity, sand addition intensity, displacement, and proppant type.

[0087] Based on the collected historical construction parameters and geostress model, the crack propagation law is simulated to obtain the value range of crack parameters, including crack length, crack width and crack height, and a crack parameter evaluation group is established.

[0088] The geostress model is part of the target well's three-dimensional geomechanical model, and the simulation of fracture propagation law also needs to be based on the target well's three-dimensional geomechanical model. That is, the range of fracture parameter values ​​is obtained based on the calculation of the target well's three-dimensional geomechanical model.

[0089] In the embodiments of this application, the optimized fracture parameters include fracture length, fracture height, and fracture width. Specifically, specialized fracturing simulation software, such as Kintix, is used. A geostress model established using Visage software can be imported, and then the collected construction parameters can be input into the corresponding geostress model to obtain the value range of each fracture parameter. For example, regarding fracture length, fracture height, and fracture width, see [link to relevant documentation]. Figure 2 For example, seam length L f The value range of is L1 to L2, the value range of seam height is H1 to H2, and the seam width is W. f The value range is W1 to W2. Within the value range of each crack parameter, the evaluation group of each crack parameter is obtained by interpolation. Finally, all the evaluation groups of crack parameters are arranged and combined to obtain multiple sets of crack parameters. The data structure of each set of crack parameters is (crack length; crack height; crack width).

[0090] Each set of fracture parameters in the fracture parameter evaluation group is input into the three-dimensional geomechanical model of the target well to construct the corresponding single-fracture productivity model.

[0091] Specifically, the fracture parameters in the designed fracture parameter evaluation group are embedded into the three-dimensional geological model of the target well (single well) to predict the production capacity after fracturing. Similarly, based on the predicted production capacity of a single well, the optimal fracture cluster spacing at different river channel locations can be selected.

[0092] Specifically, in the embodiments of this application, step S104 includes:

[0093] S1041: Constructing a single-seam productivity model:

[0094] In a specific embodiment of this application, the gas seepage from the reservoir to the fracture opening is considered to be divided into two parts: one is the radial flow part in the gas reservoir matrix, which includes two flow processes: radial flow at the fracture end with the fracture endpoint as the center and linear flow on both sides of the fracture; the other is the seepage part from the fracture end to the bottom of the well within the fracture.

[0095] It is assumed that: (1) the reservoir is homogeneous and of uniform thickness, and the gas flows in a single-phase isothermal manner; (3) the fracture is divided into n grids, and the fracture height is equal to the oil layer thickness; (4) the fracture width and fracture permeability gradually decrease along the fracture extension direction, and there is no pressure gradient within each unit; (5) steady-state flow, without considering the vertical flow of the formation. The fracture flow model is as follows: Figure 2 As shown.

[0096] The single-fracture capacity model includes a radial seepage sub-model at the fracture tip, a linear seepage sub-model on both sides of the fracture, and a non-Darcy seepage model within the fracture.

[0097] For radial flow at the fracture tip, considering the effects of the initiation pressure gradient τ, stress sensitivity, and slippage effect, the seepage differential equation is established as follows:

[0098]

[0099] Where τ is the starting pressure gradient (MPa / m), α is the stress sensitivity coefficient, and b is the slip effect coefficient.

[0100] The relationship between the seepage velocity v0 at the fracture tip and the contribution output Q0 at the fracture tip is as follows:

[0101]

[0102] Based on the equation of state for gases, the expression for the density of a gas is derived as follows:

[0103]

[0104] Substituting equations (2) and (3) into equation (1) yields:

[0105]

[0106] However, in steady-state seepage, the shape of the seepage field in a gas reservoir is stable. That is, in a circular coordinate system centered at the fracture end, the radius of the cross-section circle corresponds one-to-one with the pressure at that point. Therefore, the relationship between the radius of the cross-section circle and the pressure can be defined as follows:

[0107]

[0108] Substituting equation (5) into equation (4) and separating the variables for integration, we get:

[0109]

[0110] Introduce the following new pseudo-stress function:

[0111]

[0112] By rearranging equation (6) according to equation (7), we can obtain the radial seepage sub-model at the crack tip:

[0113]

[0114] Where h is the reservoir thickness, in meters; r e Provide the reservoir radius, m; r wfn R represents the distance (m) from the nth fracture grid to the wellbore. wf The fracture half-length is in meters (m); r is the distance from a point in the gas reservoir to the wellbore, in meters (m). wf The width of the crack is m; p gsc p is standard atmospheric pressure, MPa; p is formation supply pressure, MPa; p e The original reservoir pressure is given in MPa; p wfn The pressure of the nth crack mesh is MPa; T gsc Standard temperature (°C); T is reservoir temperature (°C); Z gsc k is the gas deviation factor. g For gas phase permeability, mD; k wfn Let mD be the permeability of the nth fracture grid; α be the stress sensitivity coefficient; b be the slippage effect coefficient; Q0 be the inflow rate at the fracture tip; Q n Q represents the flow rate within the crack mesh, where n is the crack mesh index, the first mesh index at the crack tip is 1, and n ≥ 1; wfn denoted as , where is the inflow rate across the nth crack grid; μ is the liquid viscosity (mPa·s); β is the fluid turbulence coefficient; and τ is the starting pressure gradient (MPa / m).

[0115] Similarly, for linear flow on both sides of the crack, the seepage differential equation is established:

[0116]

[0117] Where x is the seepage distance.

[0118] The injection flow rate v of the nth crack mesh n The flow rate Q of its unit cross section n The relationship is:

[0119]

[0120] Substituting equations (10) and (3) into equation (9) and rearranging, we get:

[0121]

[0122] Based on equation (7) and the integration of equation (11) with separation of variables, the linear seepage sub-model on both sides of the crack is obtained:

[0123]

[0124] After acid fracturing modification, the permeability of the acid-etched fractures is much higher than that of the matrix. Gas flow within the acid-etched fractures no longer satisfies Darcy linear flow. Therefore, the Forcheimer flow differential equation is used to address the flow within the fractures:

[0125]

[0126] Where, k f The value represents the crack permeability.

[0127] The flow velocity (flow velocity at any cross section of the mesh) in the nth crack mesh is v. fn With traffic Q wfn The relation is:

[0128]

[0129] Substituting equations (8) and (14) into equation (13) and integrating, we obtain the non-Darcy flow sub-model within the fracture:

[0130]

[0131] S1042: Solve the single-crack production capacity model to obtain the single-crack production capacity;

[0132] Establish a model to solve for the matrix, where k wfn r wfn and p wfn Q is the input parameter for the single-seam production capacity model. wfn and Q n The output results of the single-seam production capacity model are as follows:

[0133]

[0134] Where, k wfnLet mD be the permeability of the nth crack grid; r be the permeability of the crack grid. wfn Let m be the distance from the nth fracture grid to the wellbore; p wfn The pressure of the nth crack mesh, in MPa;

[0135] Q wfn Q represents the inflow rate across the nth crack mesh. n Let n be the flow rate within the crack mesh, and n be the crack mesh index. The first mesh index at the crack tip is 1, and n ≥ 1. Figure 2 As shown, the meshes are named sequentially from crack opening to crack endpoint, from 1 to n.

[0136] The solution process is as follows:

[0137] Based on the single-slit productivity model, the flow models from the matrix to the fracture mesh and within the fracture mesh are determined as follows:

[0138]

[0139] Where h is the reservoir thickness in meters (m); r e Provide the reservoir radius, in meters; R wf The fracture half-length is in meters (m); r is the distance from a point in the gas reservoir to the wellbore, in meters (m). wf The width of the crack is m; p gsc p is standard atmospheric pressure, MPa; p is formation supply pressure, MPa; p e T represents the original reservoir pressure, in MPa; gsc Standard temperature (°C); T is reservoir temperature (°C); Z gsc k is the gas deviation factor. g denoted as gas phase permeability, mD; α is the stress sensitivity coefficient; b is the slip effect coefficient; Q0 is the inflow rate at the fracture tip; μ is the liquid viscosity, mPa·s; β is the fluid turbulence coefficient; τ is the starting pressure gradient, MPa / m. This represents the average pressure from the formation to the fracture grid.

[0140] Where, k wfn The permeability of the nth fracture grid can be calculated using the permeability calculation formula in conjunction with the fracture parameters. Since the permeability of the fracture grid varies at different locations, the function f(n) is used to illustrate this.

[0141] The flow model described above is solved using an iterative method from the end of the crack to the crack opening. The flow rate Q1 of the first grid at the crack front, i.e. the crack opening grid, is then obtained, which is the single-crack output.

[0142] S1043: Obtain the optimal crack parameters based on the single-crack production rate.

[0143] Based on the single-seam production capacity model, the cumulative single-seam output within the preset production cycle is predicted;

[0144] For example, the preset production cycle can be set to 3 years. Through model calculation, the cumulative output of each crack can be predicted over 3 years for the single crack capacity model corresponding to each set of crack parameters, and a calculation result can be obtained.

[0145] The optimal crack parameters are the set of crack parameters corresponding to the single-crack capacity model that maximizes the cumulative output within the set production cycle range.

[0146] The embodiments of this application use the principle of maximizing the cumulative production over 3 years to optimize the crack parameters. Those skilled in the art can also set other optimization conditions to determine the optimal crack parameters.

[0147] Compared to the existing method of using uniform fracture design parameters for single wells, the fracture parameter design method of the present invention has the following advantages:

[0148] 1. The fracture parameter design method of this application can accurately identify reservoirs and low-permeability layers, isolate the seepage shielding zone, avoid the need to modify the seepage shielding zone, save costs, and improve the modification effect.

[0149] 2. The fracture parameter design method in this application is based on a three-dimensional geomechanical model. The fracture parameters are designed by fracture propagation and productivity prediction, which effectively ensures the optimization of the modification effect.

[0150] 3. The fracture parameter design method in this application adopts a segmented design approach to achieve targeted modification of heterogeneous tight sandstone reservoirs.

[0151] Example 2:

[0152] Based on the same technical concept, this application also provides a fracture parameter design device, including a regional geomechanical model construction unit, a target well three-dimensional geomechanical model construction unit, a single fracture productivity model construction unit, and an optimization unit, wherein:

[0153] The regional geomechanical model construction unit is used to construct a geomechanical model of the target area based on the obtained reservoir parameters, seismic parameters and well logging parameters of the target area where the reservoir is located.

[0154] The target well three-dimensional geomechanical model construction unit is used to construct a three-dimensional geomechanical model of the target well based on the target area geomechanical model and the parameter data of the target well;

[0155] The single-fracture productivity model construction unit is used to calculate fracture parameters based on the three-dimensional geomechanical model of the target well, obtain fracture parameter evaluation groups, and construct a single-fracture productivity model based on the fracture parameters.

[0156] The optimization unit is used to optimize the crack parameters based on the single-crack productivity model.

[0157] For details on the specific implementation methods, steps, and principles, please refer to the description in Example 1, which will not be repeated here.

[0158] Example 3:

[0159] Based on the same technical concept, this application also provides a machine-readable storage medium storing machine-readable program instructions, which are executed by a processor to perform the steps of the method described in Embodiment 1.

[0160] For details on the specific implementation methods, steps, and principles, please refer to the description in Example 1, which will not be repeated here.

[0161] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0162] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Additionally, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0163] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0164] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0165] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, machine-readable storage medium, such as a computer. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0166] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for designing crack parameters, characterized in that, Includes the following steps: Based on the reservoir parameters, seismic parameters, and well logging parameters obtained for the target area where the reservoir is located, a geomechanical model of the target area is constructed. A three-dimensional geomechanical model of the target well is constructed based on the geomechanical model of the target area and the parameter data of the target well. The fracture parameters are calculated based on the three-dimensional geomechanical model of the target well, a fracture parameter evaluation group is obtained, and a single fracture productivity model is constructed based on the fracture parameters in the fracture parameter evaluation group. The fracture parameters are optimized based on the single-fracture productivity model. The step prior to the step of calculating fracture parameters based on the three-dimensional geomechanical model of the target well includes the following step: The target area is divided according to the principle of similar lithological and reservoir physical property parameters; A seepage model is established for the low-permeability layer in the divided target area, and the seepage shielding zone is identified based on the seepage model; The seepage shielding zone is determined based on the area ratio of the unused portion and the degree of utilization on both sides of the interface; The process of constructing a three-dimensional geomechanical model of the target well based on the geomechanical model of the target area and the parameter data of the target well includes: Based on the identification results of the seepage shielding zone, the reservoir continuity type of the target area is determined, and the target well stimulation requirements are obtained; Obtain reservoir parameters, seismic parameters, logging parameters, and drilling parameters of the target well; After partially truncating the geomechanical model of the target area, the truncated model is corrected based on the reservoir parameters, seismic parameters, logging parameters and drilling parameters of the target well to obtain the three-dimensional geomechanical model of the target well. The steps of calculating fracture parameters based on the three-dimensional geomechanical model of the target well, obtaining a fracture parameter evaluation group, and constructing a single-fracture productivity model based on the fracture parameters in the fracture parameter evaluation group include: Historical construction parameters of the target well are collected, including: cluster spacing, fluid intensity, sand addition intensity, displacement, and proppant type. Based on the three-dimensional geomechanical model and the collected historical construction parameters, the crack propagation law is simulated to obtain the value range of crack parameters, including crack length, crack width and crack height, and a crack parameter evaluation group is established. Each set of fracture parameters in the fracture parameter evaluation group is input into the three-dimensional geomechanical model of the target well to construct the corresponding single-fracture productivity model. The optimization of the fracture parameters based on the single-fracture productivity model includes the following steps: A single-fracture capacity model is constructed, which includes a radial seepage sub-model at the fracture end, a linear seepage sub-model on both sides of the fracture, and a non-Darcy seepage model within the fracture. Solve the single-crack production capacity model to obtain the single-crack production capacity; The optimal crack parameters are obtained based on the single-crack production rate.

2. The crack parameter design method according to claim 1, characterized in that, After obtaining the three-dimensional geomechanical model of the target well, the following steps are also included: Based on the identification results of the seepage shielding zone, after isolating the seepage shielding zone, the reservoir of the target well is segmented.

3. The crack parameter design method according to claim 1, characterized in that: The radial seepage sub-model at the fracture end is as follows: The linear seepage sub-model on both sides of the crack is as follows: The non-Darcy flow sub-model within the fracture is as follows: Where h is the reservoir thickness, in meters; r e Provide the reservoir radius, m; r wfn R represents the distance (m) from the nth fracture grid to the wellbore. wf For the crack half-length, m; r wf The width of the crack is m; p gsc p is standard atmospheric pressure, MPa; p is formation supply pressure, MPa; p e The original reservoir pressure is given in MPa; p wfn The pressure of the nth crack mesh is MPa; T gsc Standard temperature (°C); T is reservoir temperature (°C); Z gsc k is the standard gas deviation factor. g For gas phase permeability, mD; k wfn Let mD be the permeability of the nth fracture grid; α be the stress sensitivity coefficient; b be the slippage effect coefficient; Q0 be the inflow rate at the fracture tip; Q n Q represents the flow rate within the crack mesh, where n is the crack mesh index, the first mesh index at the crack tip is 1, and n ≥ 1; wfn denoted as , where is the inflow rate across the nth crack grid; μ is the liquid viscosity (mPa·s); β is the fluid turbulence coefficient; and τ is the starting pressure gradient (MPa / m).

4. The crack parameter design method according to claim 3, characterized in that, The process of solving the single-crack productivity model to obtain the single-crack productivity includes: Construct a matrix, where k wfn r wfn and p wfn Q is the input parameter for the single-seam production capacity model. wfn and Q n The output results of the single-seam production capacity model are as follows: ； Where, k wfn Let mD be the permeability of the nth crack grid; r be the permeability of the crack grid. wfn Let m be the distance from the nth fracture grid to the wellbore; p wfn Q is the pressure of the nth crack mesh, in MPa; wfn The inflow rate across both sides of the nth crack mesh; Based on the single-slit productivity model, the flow models from the matrix to the fracture mesh and within the fracture mesh are determined as follows: Where h is the reservoir thickness, in meters; r e Provide the reservoir radius, in meters; R wf Let m be the half-length of the crack; r be the length of the crack. wf The width of the crack is m; p gsc p is standard atmospheric pressure, MPa; p is formation supply pressure, MPa; p e T represents the original reservoir pressure, in MPa; gsc Standard temperature (°C); T is reservoir temperature (°C); Z gsc k is the gas deviation factor. g denoted as gas phase permeability, mD; α is the stress sensitivity coefficient; b is the slip effect coefficient; Q0 is the inflow rate at the fracture tip; μ is the liquid viscosity, mPa·s; β is the fluid turbulence coefficient; τ is the starting pressure gradient, MPa / m. The flow model described above is solved using an iterative method from the end of the crack to the crack opening. The flow rate Q1 of the first grid at the crack front end obtained by the solution is the single-crack output.

5. The crack parameter design method according to claim 4, characterized in that, The step of obtaining the optimal crack parameters based on the single-crack production includes: Based on the single-seam production capacity model, the cumulative single-seam output within the preset production cycle is predicted; The set of crack parameters corresponding to the single-crack production capacity model that maximizes cumulative output is determined as the optimal crack parameters.

6. An apparatus for implementing the crack parameter design method according to any one of claims 1-5, characterized in that, include: The regional geomechanical model construction unit is used to construct a geomechanical model of the target area based on the obtained reservoir parameters, seismic parameters and well logging parameters of the target area where the reservoir is located. The target well three-dimensional geomechanical model construction unit is used to construct a three-dimensional geomechanical model of the target well based on the target area geomechanical model and the parameter data of the target well. The single-fracture productivity model construction unit is used to calculate fracture parameters based on the three-dimensional geomechanical model of the target well, obtain fracture parameter evaluation groups, and construct a single-fracture productivity model based on the fracture parameters. An optimization unit is used to optimize the crack parameters based on the single-crack productivity model.

7. A machine-readable storage medium, characterized in that, The machine-readable storage medium stores machine-readable program instructions that, when executed by a processor, perform the crack parameter design method as described in any one of claims 1 to 5.

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