Effective fracturing volume prediction method and device based on pressure failure simulation, electronic equipment and medium

Abstract

The invention discloses an effective fracturing volume prediction method and device based on pressure failure simulation, electronic equipment and a medium. The method comprises the following steps: establishing a relationship between the distance from the maximum fracture front to a fracturing point and time, and identifying an effective fracturing event; establishing a discrete seam network geological model; and calculating the effective fracturing volume based on the discrete fracture network geological model. According to the method, the interference of invalid microseism event points is reduced, the effective fracturing volume with relatively high precision is obtained, and the reliability of fracturing effect evaluation is improved.

Description

Technical Field

[0001] This invention relates to the field of microseismic data interpretation, and more specifically, to an effective method, apparatus, electronic device, and medium for predicting fracturing volume based on pressure exhaustion simulation. Background Technology

[0002] Existing microseismic fracturing monitoring technology obtains fracture attributes (principal stress direction, fracture width, density, etc.) and the swept volume (SRV) calculated from the fracture geometry based on the inverted source information. The SRV is typically the volume delineated by the farthest microseismic event point that can generate a response during stress release during fracturing operations. This SRV may have an error of several orders of magnitude compared to the actual effective fracturing volume. Fracturing fractures may close after fracturing operations, creating both closed fracture volumes and non-connected fracture volumes. International statistics show that only about 15% of fracturing fractures are supported by proppant. Therefore, a large portion of the SRV consists of non-connected fractures and closed fracture volumes. These volumes do not contribute to increased production capacity, resulting in low accuracy of microseismic fracturing volume calculations. This severely impacts development policy formulation and renders the calculation results unusable in unconventional development projects.

[0003] How to obtain the effective fracturing volume with high accuracy from microseismic event points has become a research focus of microseismic interpretation. In order to solve this problem, it is necessary to develop an effective fracturing volume prediction method, device, electronic equipment and medium based on pressure decay simulation.

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

[0005] This invention proposes a method, device, electronic equipment, and medium for predicting effective fracturing volume based on pressure exhaustion simulation. It can reduce the interference of invalid microseismic event points, obtain effective fracturing volume with high accuracy, and improve the reliability of fracturing effect evaluation.

[0006] In a first aspect, embodiments of this disclosure provide an effective fracturing volume prediction method based on pressure decay simulation, including:

[0007] Establish the relationship between the distance from the maximum fracture front to the fracturing point and time to identify effective fracturing events;

[0008] Establish a discrete fracture network geological model;

[0009] The effective fracturing volume is calculated based on the discrete fracture network geological model.

[0010] As a specific implementation of this disclosure, the relationship between the distance from the maximum fracture front to the fracturing point and time is as follows:

[0011]

[0012] Among them, D max Q represents the maximum distance from the fracture front to the fracturing point. I t represents the average fracturing flow rate, and t represents the fracturing time.

[0013] As a specific implementation of this disclosure, identifying valid fracturing events includes:

[0014] The relationship between the distance from the large fracture front to the fracturing point and time is approximately a power function. When the average displacement is determined, the effective event distribution boundary can be obtained.

[0015] Event points inside the power function curve are considered valid event points, while event points outside the power function curve are considered invalid event points.

[0016] As a specific implementation of this disclosure, establishing a discrete fracture network geological model includes:

[0017] Based on the ground stratum model, obtain the three-dimensional coordinates of the work area boundary, the projection information of all crack surfaces on the top and bottom surfaces of the work area, and establish the topological correspondence on the top and bottom surfaces;

[0018] The top surface of the work area is triangulated using Delaunay triangulation, and the triangulated nodes are mapped to the bottom surface using affine transformation.

[0019] Connect the corresponding nodes of the top and bottom surfaces to form a column, and calculate the coordinates of the column passing through other ground surfaces between the top and bottom surfaces;

[0020] Divide the model into vertical mesh layers;

[0021] Extract the matrix block mesh and the fracture surface mesh, combine the two, establish the connection relationship between them, and form the final mesh model, which is the discrete fracture mesh geological model.

[0022] As a specific implementation of this disclosure, the calculation of the effective fracturing volume based on the discrete fracture network geological model includes:

[0023] Numerical simulation of depletion development of fractured wells is performed to determine the overall pressure distribution when oil and gas well production approaches a quasi-steady state.

[0024] The critical pressure of the modified zone is determined based on the pressure distribution edge. In the layered discrete fracture model, grids with pressures lower than the critical pressure are obtained. The volume corresponding to these grids is added together to obtain the effective fracturing volume.

[0025] Secondly, embodiments of this disclosure also provide an effective fracturing volume prediction device based on pressure decay simulation, comprising:

[0026] The identification module establishes the relationship between the distance and time from the maximum fracture front to the fracturing point, and identifies effective fracturing events.

[0027] The modeling module establishes a discrete fracture network geological model.

[0028] The calculation module, based on the discrete fracture network geological model, calculates the effective fracturing volume.

[0029] As a specific implementation of this disclosure, the relationship between the distance from the maximum fracture front to the fracturing point and time is as follows:

[0030]

[0031] Among them, D max Q represents the maximum distance from the fracture front to the fracturing point. I t represents the average fracturing flow rate, and t represents the fracturing time.

[0032] As a specific implementation of this disclosure, identifying valid fracturing events includes:

[0033] The relationship between the distance from the large fracture front to the fracturing point and time is approximately a power function. When the average displacement is determined, the effective event distribution boundary can be obtained.

[0034] Event points inside the power function curve are considered valid event points, while event points outside the power function curve are considered invalid event points.

[0035] As a specific implementation of this disclosure, establishing a discrete fracture network geological model includes:

[0036] Based on the ground stratum model, obtain the three-dimensional coordinates of the work area boundary, the projection information of all crack surfaces on the top and bottom surfaces of the work area, and establish the topological correspondence on the top and bottom surfaces;

[0037] The top surface of the work area is triangulated using Delaunay triangulation, and the triangulated nodes are mapped to the bottom surface using affine transformation.

[0038] Connect the corresponding nodes of the top and bottom surfaces to form a column, and calculate the coordinates of the column passing through other ground surfaces between the top and bottom surfaces;

[0039] Divide the model into vertical mesh layers;

[0040] Extract the matrix block mesh and the fracture surface mesh, combine the two, establish the connection relationship between them, and form the final mesh model, which is the discrete fracture mesh geological model.

[0041] As a specific implementation of this disclosure, the calculation of the effective fracturing volume based on the discrete fracture network geological model includes:

[0042] Numerical simulation of depletion development of fractured wells is performed to determine the overall pressure distribution when oil and gas well production approaches a quasi-steady state.

[0043] The critical pressure of the modified zone is determined based on the pressure distribution edge. In the layered discrete fracture model, grids with pressures lower than the critical pressure are obtained. The volume corresponding to these grids is added together to obtain the effective fracturing volume.

[0044] Thirdly, embodiments of this disclosure also provide an electronic device, the electronic device comprising:

[0045] Memory, which stores executable instructions;

[0046] A processor that executes the executable instructions in the memory to implement the effective fracturing volume prediction method based on pressure decay simulation.

[0047] Fourthly, embodiments of this disclosure also provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned effective fracturing volume prediction method based on pressure decay simulation.

[0048] Its beneficial effects are as follows:

[0049] This invention applies numerical simulation methods to the calculation of the effective volume of unconventional fracturing, laying the foundation for the formulation of subsequent unconventional reservoir development policies. This invention employs a method where the distance from the fracture front to the fracturing point is approximately a power function relationship with time. When the average displacement is determined, the function curve represents the effective event distribution boundary. After identifying the effective fracturing events, a layered discrete fracture model (triangular prism mesh model) is established using the effective fracturing event points to accurately describe the internal structural characteristics and flow process of fractured reservoirs. Based on the layered discrete fracture model, considering factors such as reservoir size, porosity, permeability, rock brittleness, water sensitivity, and fracture mesh size, a rapid numerical simulation of depletion development is performed on the fractured well. When the oil and gas well production approaches a quasi-steady state, the overall pressure decreases synchronously while the relative magnitude of the pressure remains unchanged. This time period is selected to obtain the overall pressure distribution, which is generally funnel-shaped. The critical pressure PC of the stimulated zone is determined based on the edge of the pressure funnel. Then, tetrahedral meshes with pressures smaller than this value are identified, and the volume corresponding to these meshes is summed to obtain the effective fracturing volume, greatly improving the calculation accuracy of the effective fracturing volume.

[0050] The methods and apparatus of the present invention have other features and advantages that will be apparent from or will be set forth in detail in the accompanying drawings and following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0051] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same parts.

[0052] Figure 1 A flowchart illustrating the steps of an effective fracturing volume prediction method based on pressure decay simulation according to an embodiment of the present invention is shown.

[0053] Figure 2 A schematic diagram of constructing an effective fracturing identification boundary map by time-distance intersection according to an embodiment of the present invention is shown.

[0054] Figure 3 A schematic top view of a fracturing fracture network according to an embodiment of the present invention is shown.

[0055] Figure 4a , Figure 4b Schematic diagrams of a layered discrete crack model, a crack surface, and a matrix mesh model according to an embodiment of the present invention are shown respectively.

[0056] Figure 5a , Figure 5b The diagrams show the relationship between Q / Δp and time obtained from a digital model according to an embodiment of the present invention, and a schematic diagram of the pressure drop funnel.

[0057] Figure 6 A schematic diagram illustrating a simulated pressure drop process during exhaustion development of three wells according to an embodiment of the present invention is shown.

[0058] Figure 7 A top view of the effective fracturing volume according to an embodiment of the present invention is shown.

[0059] Figure 8 A histogram comparing the single-well productivity analysis results according to an embodiment of the present invention is shown.

[0060] Figure 9 A block diagram of an effective fracturing volume prediction device based on pressure decay simulation according to an embodiment of the present invention is shown.

[0061] Explanation of reference numerals in the attached figures:

[0062] 201. Recognition Module; 202. Modeling Module; 203. Calculation Module; 204. ; 205. ; 206. ; Detailed Implementation

[0063] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0064] To facilitate understanding of the solutions and effects of the embodiments of the present invention, six specific application examples are given below. Those skilled in the art should understand that these examples are merely for the purpose of understanding the present invention, and any specific details therein are not intended to limit the present invention in any way.

[0065] Example 1

[0066] Figure 1 A flowchart illustrating the steps of an effective fracturing volume prediction method based on pressure decay simulation according to an embodiment of the present invention is shown.

[0067] like Figure 1 As shown, the effective fracturing volume prediction method based on pressure decay simulation includes:

[0068] Step 101: Establish the relationship between the distance from the maximum fracture front to the fracturing point and time, and identify effective fracturing events;

[0069] Step 102: Establish a discrete fracture network geological model;

[0070] Step 103: Calculate the effective fracturing volume based on the discrete fracture network geological model.

[0071] In one example, the relationship between the distance from the maximum fracture front to the fracturing point and time is as follows:

[0072]

[0073] Among them, D max Q represents the maximum distance from the fracture front to the fracturing point. I t represents the average fracturing flow rate, and t represents the fracturing time.

[0074] In one example, identifying valid fracturing events includes:

[0075] The relationship between the distance from the large fracture front to the fracturing point and time is approximately a power function. When the average displacement is determined, the effective event distribution boundary can be obtained.

[0076] Event points inside the power function curve are considered valid event points, while event points outside the power function curve are considered invalid event points.

[0077] In one example, building a discrete fracture network geological model includes:

[0078] Based on the ground stratum model, obtain the three-dimensional coordinates of the work area boundary, the projection information of all crack surfaces on the top and bottom surfaces of the work area, and establish the topological correspondence on the top and bottom surfaces;

[0079] The top surface of the work area is triangulated using Delaunay triangulation, and the triangulated nodes are mapped to the bottom surface using affine transformation.

[0080] Connect the corresponding nodes of the top and bottom surfaces to form a column, and calculate the coordinates of the column passing through other ground surfaces between the top and bottom surfaces;

[0081] Divide the model into vertical mesh layers;

[0082] Extract the matrix block mesh and the fracture surface mesh, combine the two, establish the connection relationship between them, and form the final mesh model, which is the discrete fracture mesh geological model.

[0083] In one example, based on a discrete fracture network geological model, the effective fracturing volume is calculated as follows:

[0084] Numerical simulation of depletion development of fractured wells is performed to determine the overall pressure distribution when oil and gas well production approaches a quasi-steady state.

[0085] The critical pressure of the modified zone is determined based on the pressure distribution edge. In the layered discrete fracture model, grids with pressures lower than the critical pressure are obtained. The volume corresponding to these grids is added together to obtain the effective fracturing volume.

[0086] Specifically, effective fracturing events are identified. Shapiro proposes that in the initial stage of fracturing, the fracture length L and fracturing time t approximately satisfy the following linear relationship:

[0087]

[0088] Among them, Q I h is the average fracturing flow rate. f Let w represent the average fracture height and w represent the average fracture width. Approximating the linear relationship between the distance from the fracture front to the fracturing point and the fracturing time is based on the assumption that the average fracturing flow rate, average fracture height, and fracture width are constants. In actual fracturing, only the average flow rate is constant; the fracture height and width are variables. Theoretically, the relationship between average flow rate and fracturing volume is:

[0089] Q I t=Lh f w

[0090] The distance from the fracture front to the fracturing point is:

[0091]

[0092] If x = max{L, hf, w}, then the maximum value of D is:

[0093]

[0094] Substituting this into the relationship between average displacement and fracturing volume, we get:

[0095]

[0096] Then there is

[0097]

[0098] That is, the distance from the maximum fracture front to the fracturing point is approximately a power function relationship with time. When the average displacement is determined, the effective event distribution boundary can be obtained. The points inside the power function curve are effective event points, and the event points outside the power function curve are invalid event points.

[0099] A layered discrete fracture model (triangular prism mesh model) was established. This mesh system facilitates corner mesh modeling, provides an intuitive model, and can effectively describe the flow process within the layer. Simultaneously, the discrete fracture model uses mesh partitioning based on the fracture network, accurately describing the internal structural features and flow processes of fractured reservoirs.

[0100] The implementation process of this model is as follows:

[0101] (1) Obtain the three-dimensional coordinates of the work area boundary from the existing ground surface model in the work area, the projection information of all crack surfaces on the top and bottom surfaces of the work area, and establish the topological correspondence on the top and bottom surfaces;

[0102] (2) With the crack projection information included, the top surface of the work area is triangulated by Delaunay and the nodes after triangulation are mapped to the bottom surface by affine transformation.

[0103] (3) Connect the corresponding nodes of the top and bottom surfaces to form a column. Calculate the coordinates of the columns passing through other ground surfaces between the top and bottom surfaces;

[0104] (4) Divide the model into vertical mesh layers according to the needs of numerical simulation;

[0105] (5) Extract the matrix block mesh (triangular frustum) and crack surface mesh (quadrilateral), and combine the two to establish the connection relationship between them to form the final mesh model.

[0106] Calculate the effective fracturing volume. Based on the layered discrete fracture model, and comprehensively considering factors such as reservoir size, porosity, permeability, rock brittleness, water sensitivity, and fracture network size, a rapid depletion development numerical simulation is performed on the fracturing well. When the well production approaches a quasi-steady state, the overall pressure decreases synchronously while the relative magnitude of the pressure remains constant. This time period is selected to obtain the overall pressure distribution, which is generally funnel-shaped. The critical pressure PC of the stimulated zone is determined based on the edge of the pressure funnel. Then, tetrahedral meshes with pressures smaller than this value are identified, and the volume corresponding to these meshes is summed to obtain the effective fracturing volume.

[0107] Example 2

[0108] The present invention also provides an effective fracturing volume prediction device based on pressure decay simulation, comprising:

[0109] The identification module establishes the relationship between the distance and time from the maximum fracture front to the fracturing point, and identifies effective fracturing events.

[0110] The modeling module establishes a discrete fracture network geological model.

[0111] The calculation module, based on the discrete fracture network geological model, calculates the effective fracturing volume.

[0112] In one example, the relationship between the distance from the maximum fracture front to the fracturing point and time is as follows:

[0113]

[0114] Among them, D max Q represents the maximum distance from the fracture front to the fracturing point. I t represents the average fracturing flow rate, and t represents the fracturing time.

[0115] In one example, identifying valid fracturing events includes:

[0116] The relationship between the distance from the large fracture front to the fracturing point and time is approximately a power function. When the average displacement is determined, the effective event distribution boundary can be obtained.

[0117] Event points inside the power function curve are considered valid event points, while event points outside the power function curve are considered invalid event points.

[0118] In one example, building a discrete fracture network geological model includes:

[0119] Based on the ground stratum model, obtain the three-dimensional coordinates of the work area boundary, the projection information of all crack surfaces on the top and bottom surfaces of the work area, and establish the topological correspondence on the top and bottom surfaces;

[0120] The top surface of the work area is triangulated using Delaunay triangulation, and the triangulated nodes are mapped to the bottom surface using affine transformation.

[0121] Connect the corresponding nodes of the top and bottom surfaces to form a column, and calculate the coordinates of the column passing through other ground surfaces between the top and bottom surfaces;

[0122] Divide the model into vertical mesh layers;

[0123] Extract the matrix block mesh and the fracture surface mesh, combine the two, establish the connection relationship between them, and form the final mesh model, which is the discrete fracture mesh geological model.

[0124] In one example, based on a discrete fracture network geological model, the effective fracturing volume is calculated as follows:

[0125] Numerical simulation of depletion development of fractured wells is performed to determine the overall pressure distribution when oil and gas well production approaches a quasi-steady state.

[0126] The critical pressure of the modified zone is determined based on the pressure distribution edge. In the layered discrete fracture model, grids with pressures lower than the critical pressure are obtained. The volume corresponding to these grids is added together to obtain the effective fracturing volume.

[0127] Specifically, effective fracturing events are identified. Shapiro proposes that in the initial stage of fracturing, the fracture length L and fracturing time t approximately satisfy the following linear relationship:

[0128]

[0129] Among them, Q I h is the average fracturing flow rate. f Let w represent the average fracture height and w represent the average fracture width. Approximating the linear relationship between the distance from the fracture front to the fracturing point and the fracturing time is based on the assumption that the average fracturing flow rate, average fracture height, and fracture width are constants. In actual fracturing, only the average flow rate is constant; the fracture height and width are variables. Theoretically, the relationship between average flow rate and fracturing volume is:

[0130] Q I t=Lh f w

[0131] The distance from the fracture front to the fracturing point is:

[0132]

[0133] If x = max{L, hf, w}, then the maximum value of D is:

[0134]

[0135] Substituting this into the relationship between average displacement and fracturing volume, we get:

[0136]

[0137] Then there is

[0138]

[0139] That is, the distance from the maximum fracture front to the fracturing point is approximately a power function relationship with time. When the average displacement is determined, the effective event distribution boundary can be obtained. The points inside the power function curve are effective event points, and the event points outside the power function curve are invalid event points.

[0140] A layered discrete fracture model (triangular prism mesh model) was established. This mesh system facilitates corner mesh modeling, provides an intuitive model, and can effectively describe the flow process within the layer. Simultaneously, the discrete fracture model uses mesh partitioning based on the fracture network, accurately describing the internal structural features and flow processes of fractured reservoirs.

[0141] The implementation process of this model is as follows:

[0142] (1) Obtain the three-dimensional coordinates of the work area boundary from the existing ground surface model in the work area, the projection information of all crack surfaces on the top and bottom surfaces of the work area, and establish the topological correspondence on the top and bottom surfaces;

[0143] (2) With the crack projection information included, the top surface of the work area is triangulated by Delaunay and the nodes after triangulation are mapped to the bottom surface by affine transformation.

[0144] (3) Connect the corresponding nodes of the top and bottom surfaces to form a column. Calculate the coordinates of the columns passing through other ground surfaces between the top and bottom surfaces;

[0145] (4) Divide the model into vertical mesh layers according to the needs of numerical simulation;

[0146] (5) Extract the matrix block mesh (triangular frustum) and crack surface mesh (quadrilateral), and combine the two to establish the connection relationship between them to form the final mesh model.

[0147] Calculate the effective fracturing volume. Based on the layered discrete fracture model, and comprehensively considering factors such as reservoir size, porosity, permeability, rock brittleness, water sensitivity, and fracture network size, a rapid depletion development numerical simulation is performed on the fracturing well. When the well production approaches a quasi-steady state, the overall pressure decreases synchronously while the relative magnitude of the pressure remains constant. This time period is selected to obtain the overall pressure distribution, which is generally funnel-shaped. The critical pressure PC of the stimulated zone is determined based on the edge of the pressure funnel. Then, tetrahedral meshes with pressures smaller than this value are identified, and the volume corresponding to these meshes is summed to obtain the effective fracturing volume.

[0148] Example 3

[0149] In a certain exploration area in Southwest China, the evaluation of traditional fracturing effects mainly relies on a general estimation of fracture geometric parameters (length, width, height, and principal orientation) based on microseismic event points, and the swept volume (SRV) calculated from these parameters. The SRV is typically the volume delineated by the farthest microseismic event point that can generate a response during stress release during fracturing, which may have an error of several orders of magnitude compared to the actual effective fracturing volume. Fracturing-induced fractures may close after fracturing, creating both closed fracture volumes and non-connected fracture volumes. International statistics show that only about 15% of fracturing fractures are supported by proppant. Therefore, a large portion of the SRV consists of non-connected fractures and closed fracture volumes. These volumes do not contribute to increased production capacity, resulting in low accuracy of microseismic fracturing volume calculations. This severely impacts development policy formulation and renders the calculation results unusable in unconventional development. This invention proposes a method for modeling layered discrete fractures based on hydraulic fracturing. By developing numerical simulations to obtain a quasi-steady-state pressure field through pressure decay, the grid volume within the pressure variation range is calculated to obtain the effective fracturing volume. The production capacity prediction results obtained by numerical simulation based on the effective fracturing volume obtained by this method are compared and analyzed with the cumulative gas production results obtained by the single-well production dynamic method to verify the reliability of the method.

[0150] Figure 2 A schematic diagram of constructing an effective fracturing identification boundary map by time-distance intersection according to an embodiment of the present invention is shown.

[0151] Figure 3 A schematic top view of a fracturing fracture network according to an embodiment of the present invention is shown.

[0152] Based on the theoretical relationship between average displacement and fracturing volume, the distance from the fracture front to the fracturing point and the fracturing time are approximated as a linear relationship. This is based on the premise that the average fracturing displacement, average fracture height, and fracture width are constants. In actual fracturing, only the average displacement is constant; fracture height and fracture width are variables. The distance from the maximum fracture front to the fracturing point and time approximates a power function relationship. When the average displacement is determined, the effective event distribution boundary can be obtained. Therefore, statistical regression is performed on the fracture distance at the fracturing event point and the fracturing event time to establish a power function relationship, such as... Figure 2 As shown, the right side of the well trajectory represents positive events, and the left side represents negative events. Events inside the power function curve are valid event points, while those outside are invalid. After removing invalid event points, a fracture network is constructed based on the "point-fracture" connection criterion. It is assumed that hydraulic fracturing fractures follow a "fracture tree growth method," starting from the fracturing point (root), forming the main fracture (trunk), then the secondary fractures (branches), and so on. Based on this criterion, a fracture path calculation method based on the "point-fracture" connection criterion is programmed, and the fracture network is constructed as follows: Figure 3 As shown.

[0153] A layered discrete fracture model (triangular prism mesh model) was established. This mesh system facilitates corner mesh modeling, provides an intuitive model, and can effectively describe the flow process within the layer. Simultaneously, the discrete fracture model uses mesh partitioning based on the fracture network to accurately describe the internal structural features and flow processes of fractured reservoirs. The model implementation process is as follows:

[0154] (1) Obtain the three-dimensional coordinates of the work area boundary from the existing ground surface model in the work area, the projection information of all crack surfaces on the top and bottom surfaces of the work area, and establish the topological correspondence on the top and bottom surfaces;

[0155] (2) With the crack projection information included, the top surface of the work area is triangulated by Delaunay and the nodes after triangulation are mapped to the bottom surface by affine transformation.

[0156] (3) Connect the corresponding nodes of the top and bottom surfaces to form a column. Calculate the coordinates of the columns passing through other ground surfaces between the top and bottom surfaces;

[0157] (4) Divide the model into vertical mesh layers according to the needs of numerical simulation;

[0158] (5) Extract the matrix block mesh (triangular frustum) and crack surface mesh (quadrilateral), and combine the two to establish the connection relationship between them to form the final mesh model.

[0159] Figure 4a , Figure 4b Schematic diagrams of a layered discrete crack model, a crack surface, and a matrix mesh model according to an embodiment of the present invention are shown respectively.

[0160] Figure 4a A layered discrete fracture model was established based on the fracture network reconstructed at microseismic event points for three wells on a certain platform. Figure 4b The final identified crack surface mesh and matrix mesh model.

[0161] Figure 5a , Figure 5b The diagrams show the relationship between Q / Δp and time obtained from a digital model according to an embodiment of the present invention, and a schematic diagram of the pressure drop funnel.

[0162] Figure 6 A schematic diagram illustrating a simulated pressure drop process during exhaustion development of three wells according to an embodiment of the present invention is shown.

[0163] Figure 7 A top view of the effective fracturing volume according to an embodiment of the present invention is shown.

[0164] Figure 8 A histogram comparing the single-well productivity analysis results according to an embodiment of the present invention is shown.

[0165] Calculate the effective fracturing volume. Perform a rapid numerical simulation of well depletion development. When the well production approaches a quasi-steady state, the pressure decreases synchronously across the entire field, while the relative pressure magnitude remains constant. To determine the time when the system enters the quasi-steady state, plot the ratio of production Q to the reservoir average pressure drop Δp, as shown below. Figure 5a As shown, after more than 4 years of production, Q / Δp is basically stable, and the system can be considered to have reached a quasi-steady-state flow. The pressure field at any time t after this point is selected for analysis. Therefore, this time period can be used to obtain the overall pressure distribution, which is generally called a funnel shape, such as... Figure 5b As shown, the critical pressure PC of the reformed zone is determined based on the edge of the pressure funnel. Then, tetrahedral grids with pressures smaller than this value are identified, and the volume corresponding to these grids is summed to obtain the effective fracturing volume. Taking into account factors such as reservoir size, porosity, permeability, rock brittleness, water sensitivity, and fracturing grid size, a fracturing well depletion development simulation is performed. The pressure field changes during depletion development as shown in the figure. Figure 6 As shown, the effective fracturing volume of the three wells on the platform was finally obtained as follows: Figure 7 As shown, the production capacity prediction based on the effective fracturing volume is compared with the final production capacity obtained by fitting the historical production dynamics of a single well. Since reservoir development has entered the mid-to-late stages, a production decline curve can be fitted based on the historical production data of a single well. By combining the decline pattern with the lower limit parameter of economic evaluation, a more realistic production capacity of a single well can be obtained. This is the most commonly used production capacity prediction method in oilfield development practice. Figure 8 As shown, the predicted production capacity of the three wells on this platform based on the effective fracturing volume is 178 million cubic meters, 135 million cubic meters, and 120 million cubic meters, respectively. The results obtained by fitting the historical production data of the three wells are 170 million cubic meters, 140 million cubic meters, and 130 million cubic meters, respectively, and the two are in very high agreement.

[0166] Example 4

[0167] Figure 9 A block diagram of an effective fracturing volume prediction device based on pressure decay simulation according to an embodiment of the present invention is shown.

[0168] like Figure 9 As shown, the effective fracturing volume prediction device based on pressure decay simulation includes:

[0169] The identification module 201 establishes the relationship between the distance from the maximum fracture front to the fracturing point and time, and identifies effective fracturing events;

[0170] Modeling module 202, establishes a discrete fracture network geological model;

[0171] Calculation module 203 calculates the effective fracturing volume based on the discrete fracture network geological model.

[0172] In one example, the relationship between the distance from the maximum fracture front to the fracturing point and time is as follows:

[0173]

[0174] Among them, D max Q represents the maximum distance from the fracture front to the fracturing point. I t represents the average fracturing flow rate, and t represents the fracturing time.

[0175] In one example, identifying valid fracturing events includes:

[0176] The relationship between the distance from the large fracture front to the fracturing point and time is approximately a power function. When the average displacement is determined, the effective event distribution boundary can be obtained.

[0177] Event points inside the power function curve are considered valid event points, while event points outside the power function curve are considered invalid event points.

[0178] In one example, building a discrete fracture network geological model includes:

[0179] Based on the ground stratum model, obtain the three-dimensional coordinates of the work area boundary, the projection information of all crack surfaces on the top and bottom surfaces of the work area, and establish the topological correspondence on the top and bottom surfaces;

[0180] The top surface of the work area is triangulated using Delaunay triangulation, and the triangulated nodes are mapped to the bottom surface using affine transformation.

[0181] Connect the corresponding nodes of the top and bottom surfaces to form a column, and calculate the coordinates of the column passing through other ground surfaces between the top and bottom surfaces;

[0182] Divide the model into vertical mesh layers;

[0183] Extract the matrix block mesh and the fracture surface mesh, combine the two, establish the connection relationship between them, and form the final mesh model, which is the discrete fracture mesh geological model.

[0184] In one example, based on a discrete fracture network geological model, the effective fracturing volume is calculated as follows:

[0185] Numerical simulation of depletion development of fractured wells is performed to determine the overall pressure distribution when oil and gas well production approaches a quasi-steady state.

[0186] The critical pressure of the modified zone is determined based on the pressure distribution edge. In the layered discrete fracture model, grids with pressures lower than the critical pressure are obtained. The volume corresponding to these grids is added together to obtain the effective fracturing volume.

[0187] Example 5

[0188] This disclosure provides an electronic device, comprising: a memory storing executable instructions; and a processor executing the executable instructions in the memory to implement the above-described effective fracturing volume prediction method based on pressure decay simulation.

[0189] An electronic device according to an embodiment of the present disclosure includes a memory and a processor.

[0190] This memory is used to store non-transitory computer-readable instructions. Specifically, the memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory. The non-volatile memory may, for example, include read-only memory (ROM), hard disk, flash memory, etc.

[0191] The processor may be a central processing unit (CPU) or other form of processing unit with data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions. In one embodiment of this disclosure, the processor is used to execute computer-readable instructions stored in the memory.

[0192] Those skilled in the art will understand that, in order to solve the technical problem of how to achieve a good user experience, this embodiment may also include well-known structures such as communication buses and interfaces, and these well-known structures should also be included within the protection scope of this disclosure.

[0193] For a detailed description of this embodiment, please refer to the corresponding descriptions in the foregoing embodiments, which will not be repeated here.

[0194] Example 6

[0195] This disclosure provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the effective fracturing volume prediction method based on pressure decay simulation.

[0196] A computer-readable storage medium according to embodiments of the present disclosure stores non-transitory computer-readable instructions. When these non-transitory computer-readable instructions are executed by a processor, all or part of the steps of the methods described in the foregoing embodiments of the present disclosure are performed.

[0197] The aforementioned computer-readable storage media include, but are not limited to: optical storage media (e.g., CD-ROM and DVD), magneto-optical storage media (e.g., MO), magnetic storage media (e.g., magnetic tape or portable hard drive), media with built-in rewritable non-volatile memory (e.g., memory card), and media with built-in ROM (e.g., ROM cartridge).

[0198] Those skilled in the art should understand that the above description of the embodiments of the present invention is only intended to illustrate the beneficial effects of the embodiments of the present invention, and is not intended to limit the embodiments of the present invention to any of the examples given.

[0199] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for predicting effective fracturing volume based on pressure decay simulation, characterized in that, include: Establish the relationship between the distance from the maximum fracture front to the fracturing point and time to identify effective fracturing events; Establish a discrete fracture network geological model; The effective fracturing volume is calculated based on the discrete fracture network geological model.

2. The effective fracturing volume prediction method based on pressure decay simulation according to claim 1, wherein, The relationship between the distance from the maximum fracture front to the fracturing point and time is as follows: Among them, D max Q represents the maximum distance from the fracture front to the fracturing point. I t represents the average fracturing flow rate, and t represents the fracturing time.

3. The effective fracturing volume prediction method based on pressure decay simulation according to claim 2, wherein, Identifying valid fracturing events includes: The relationship between the distance from the large fracture front to the fracturing point and time is approximately a power function. When the average displacement is determined, the effective event distribution boundary can be obtained. Event points inside the power function curve are considered valid event points, while event points outside the power function curve are considered invalid event points.

4. The effective fracturing volume prediction method based on pressure decay simulation according to claim 1, wherein, Establishing a discrete fracture network geological model includes: Based on the ground stratum model, obtain the three-dimensional coordinates of the work area boundary, the projection information of all crack surfaces on the top and bottom surfaces of the work area, and establish the topological correspondence on the top and bottom surfaces; The top surface of the work area is triangulated using Delaunay triangulation, and the triangulated nodes are mapped to the bottom surface using affine transformation. Connect the corresponding nodes of the top and bottom surfaces to form a column, and calculate the coordinates of the column passing through other ground surfaces between the top and bottom surfaces; Divide the model into vertical mesh layers; Extract the matrix block mesh and the fracture surface mesh, combine the two, establish the connection relationship between them, and form the final mesh model, which is the discrete fracture mesh geological model.

5. The effective fracturing volume prediction method based on pressure decay simulation according to claim 4, wherein, Based on the discrete fracture network geological model, the effective fracturing volume is calculated as follows: Numerical simulation of depletion development of fractured wells is performed to determine the overall pressure distribution when oil and gas well production approaches a quasi-steady state. The critical pressure of the modified zone is determined based on the pressure distribution edge. In the layered discrete fracture model, grids with pressures lower than the critical pressure are obtained. The volume corresponding to these grids is added together to obtain the effective fracturing volume.

6. An effective fracturing volume prediction device based on pressure decay simulation, characterized in that, include: The identification module establishes the relationship between the distance and time from the maximum fracture front to the fracturing point, and identifies effective fracturing events. The modeling module establishes a discrete fracture network geological model. The calculation module, based on the discrete fracture network geological model, calculates the effective fracturing volume.

7. The effective fracturing volume prediction device based on pressure decay simulation according to claim 6, wherein, The relationship between the distance from the maximum fracture front to the fracturing point and time is as follows: Among them, D max Q represents the maximum distance from the fracture front to the fracturing point. I t represents the average fracturing flow rate, and t represents the fracturing time.

8. The effective fracturing volume prediction device based on pressure decay simulation according to claim 7, wherein, Identifying valid fracturing events includes: The relationship between the distance from the large fracture front to the fracturing point and time is approximately a power function. When the average displacement is determined, the effective event distribution boundary can be obtained. Event points inside the power function curve are considered valid event points, while event points outside the power function curve are considered invalid event points.

9. An electronic device, characterized in that, The electronic device includes: Memory, which stores executable instructions; A processor that executes the executable instructions in the memory to implement the effective fracturing volume prediction method based on pressure decay simulation as described in any one of claims 1-5.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the effective fracturing volume prediction method based on pressure decay simulation as described in any one of claims 1-5.

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