An evaluation method and device for the active utilization effect of the spatial stress field of a three-dimensional well pattern

Abstract

This article relates to the field of oil and gas field development engineering, and particularly relates to a method and device for evaluating the active utilization effect of the spatial stress field of a three-dimensional well pattern. The method includes obtaining a Mohr circle envelope line applicable to the rocks of the target layer based on a large number of indoor experiments on the target layer in the work area or empirical data from adjacent blocks; partitioning the space according to the Mohr circle envelope line and the spatial stress state of each point in the space of the three-dimensional well pattern, where the spatial stress state is the superposition of the spatial induced stress of each crack in the space on each point in the space and the original in-situ stress; calculating the active utilization coefficient of the stress field according to the size, position of the space, the weights of each partition in the space, and the proportion of the induced stress of each crack in the space on each point in the space; quantitatively evaluating the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field. Through the embodiments of this article, the quantitative evaluation of the active utilization effect of the spatial stress field is realized, thereby improving the evaluation accuracy.

Description

Technical Field

[0001] This article relates to the field of oil and gas field development engineering, and particularly relates to an evaluation method and device for the active utilization effect of the spatial stress field of a three-dimensional well pattern. Background Art

[0002] Tight oil and gas reservoirs generally have the characteristics of low porosity and low permeability. During the development process, large-scale hydraulic fracturing technology is required to create a large-scale artificial fracture network, thereby increasing the matrix conductivity and achieving the purpose of improving resource utilization rate and recovery rate, and ultimately realizing efficient development. During hydraulic fracturing, a large amount of fracturing fluid and proppant need to be injected into the rock formation in a short time, thereby changing the stress state of the rock formation and causing rock fractures, and finally forming a connected fracture network structure. At the same time, the large amount of injected fracturing fluid and proppant will generate induced stress around the fractures. When multiple wells are fractured synchronously or in a zipper-like manner, the induced stresses generated by each fracture will be superimposed on each other, forming a complex spatial stress. However, well interference is not necessarily negative for development. Under the condition of three-dimensional development, by arranging a three-dimensional well pattern and staggered fractures, the well interference is "changed from passive to active", and the well interference-induced stress field is used to create complex fractures, thereby improving the degree of inter-well utilization and recovery rate.

[0003] In the existing evaluation methods for the active utilization effect of the spatial stress field of a three-dimensional well pattern, it is difficult to quantitatively evaluate the active utilization effect of the spatial stress field of a three-dimensional well pattern, resulting in the inability to fully utilize the spatial induced stress field to assist in creating complex fractures, and further resulting in low inter-well utilization degree and low recovery rate.

[0004] There is an urgent need for an evaluation method for the active utilization effect of the spatial stress field of a three-dimensional well pattern to solve the problems that it is difficult to quantitatively evaluate the active utilization effect of the spatial stress field of a three-dimensional well pattern and the evaluation accuracy is low in the evaluation method for the active utilization effect of the spatial stress field of a three-dimensional well pattern. Summary of the Invention

[0005] To solve the problems that it is difficult to quantitatively evaluate the active utilization effect of the spatial stress field of a three-dimensional well pattern and the evaluation accuracy is low in the existing evaluation methods for the active utilization effect of the spatial stress field of a three-dimensional well pattern, the embodiments of this article provide an evaluation method and device for the active utilization effect of the spatial stress field of a three-dimensional well pattern, realizing the quantitative evaluation of the active utilization effect of the spatial stress field, and further improving the evaluation accuracy.

[0006] To solve the above technical problems, the specific technical solutions of this article are as follows:

[0007] On the one hand, the embodiments of this article provide an evaluation method for the active utilization effect of the spatial stress field of a three-dimensional well pattern, including:

[0008] Obtaining the Mohr circle envelope line applicable to the target layer rock based on a large number of indoor experiments or empirical data of adjacent blocks in the target area of the work area;

[0009] Partition the space according to the Mohr circle envelope and the spatial stress state of each point in the space of the three-dimensional well pattern, where the spatial stress state includes the superposition of the spatial induced stress of each fracture in the space on each point in the space and the original in-situ stress field;

[0010] Calculate the active utilization coefficient of the stress field according to the size, position of the space, the weights of each partition in the space, and the proportion of the induced stress of each fracture in the space on each point in the space;

[0011] Quantitatively evaluate the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field.

[0012] Further, the partition includes a fracture zone, a reticular fracture formation potential zone, a simple fracture formation potential zone, and a non-fracture potential zone.

[0013] Further, partitioning the space according to the Mohr circle envelope and the spatial stress state of each point in the space of the three-dimensional well pattern further includes,

[0014] Calculate the horizontal maximum principal stress, horizontal minimum principal stress, and vertical stress of each point according to the spatial stress state of each point in the space;

[0015] Calculate the overlapping area of the Mohr circles of each point according to the horizontal maximum principal stress, horizontal minimum principal stress, and vertical stress;

[0016] Divide each point in the space into the fracture zone, the reticular fracture formation potential zone, the simple fracture formation potential zone, or the non-fracture potential zone according to the overlapping area of the Mohr circles of each point and the Mohr circle envelope.

[0017] Further, dividing each point in the space into the fracture zone, the reticular fracture formation potential zone, the simple fracture formation potential zone, or the non-fracture potential zone according to the overlapping area of the Mohr circles of each point and the Mohr circle envelope further includes,

[0018] Compare the shear stress corresponding to each normal stress in the overlapping area of the Mohr circles with the shear stress corresponding to this normal stress in the Mohr circle envelope;

[0019] If there is at least one shear stress T1 corresponding to a normal stress in the overlapping area of the Mohr circles of a certain point that is greater than the shear stress T2 corresponding to this normal stress in the Mohr circle envelope, and the difference between the shear stress T1 and the shear stress T2 is greater than a preset range, then this point belongs to the fracture zone;

[0020] If the shear stress T1 corresponding to all the normal stresses in the overlapping area of the Mohr circles at a certain point is less than the shear stress T2 corresponding to all these normal stresses in the Mohr circle envelope, and the difference between the shear stress T2 and the shear stress T1 is greater than the preset range, then this point belongs to the non-crack potential zone;

[0021] If the maximum shear stress T1 in the overlapping area of the Mohr circles at a certain point is greater than or equal to the shear stress T2 corresponding to the normal stress of this maximum shear stress T1 in the Mohr circle envelope, and the difference between the maximum shear stress T1 and the shear stress T2 is less than or equal to the preset range, or, if the maximum shear stress T1 in the overlapping area of the Mohr circles at a certain point is less than the shear stress T2 corresponding to the normal stress of this maximum shear stress T1 in the Mohr circle envelope, and the difference between the shear stress T2 and the maximum shear stress T1 is less than or equal to the preset range, then calculate the horizontal stress difference coefficient at this point according to the spatial stress field at this point;

[0022] If the horizontal stress difference coefficient at this point is less than the preset threshold value, then this point belongs to the reticular fracture formation potential zone;

[0023] If the horizontal stress difference coefficient at this point is greater than or equal to the preset threshold value, then this point belongs to the simple fracture formation potential zone.

[0024] Further, the preset range is 5% of the shear stress T2.

[0025] Further, the formula for calculating the active utilization coefficient of the stress field according to the size of the space, the weights of each partition in the space, and the proportion of the induced stress of each crack in the space on each point in the space is,

[0026]

[0027] represents the number of grids divided by x, y, and z of the space, φ represents the weight of the partition, k represents the number of partitions, γ represents the proportion of the induced stress, and m represents the number of those ranked in the front in the descending order of the proportion of the induced stress;

[0028] Among them, the formula for calculating the proportion of the induced stress is,

[0029]

[0030] Among them, γ represents the proportion of the induced stress, σ j (x, y, z) represents the spatial induced stress of the j-th crack in the space on the point with coordinates x, y, z, and n represents the number of cracks in the space.

[0031] Further, quantitatively evaluating the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field further includes,

[0032] Evaluate the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field and a preset threshold value of the active utilization coefficient.

[0033] On the other hand, an embodiment of the present disclosure also provides an evaluation device for the active utilization effect of a spatial stress field in a three-dimensional well pattern. The device includes:

[0034] A Mohr circle envelope acquisition unit configured to acquire a Mohr circle envelope applicable to the rock of the target layer based on a large number of indoor experiments on the target layer in the work area or empirical data of adjacent blocks;

[0035] A spatial stress field zoning unit configured to zone the space according to the Mohr circle envelope and the spatial stress state of each point in the space of the three-dimensional well pattern, where the spatial stress field includes the superposition of the spatial induced stress and the original in-situ stress of each crack in the space on each point in the space;

[0036] An active utilization coefficient calculation unit of the stress field configured to calculate the active utilization coefficient of the stress field according to the size, position of the space, the weights of each zone in the space, and the proportion of the induced stress of each crack in the space on each point in the space;

[0037] A quantitative evaluation unit of the active utilization effect of the spatial stress field configured to quantitatively evaluate the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field.

[0038] On the other hand, an embodiment of the present disclosure also provides a computer device, including a memory, a processor, and a computer program stored on the memory. When the processor executes the computer program, the above method is implemented.

[0039] Finally, an embodiment of the present disclosure also provides a computer storage medium, on which a computer program is stored. When the computer program is run by the processor of the computer device, the above method is executed.

[0040] Using the embodiments of the present disclosure, zone the space according to the Mohr circle envelope applicable to the three-dimensional well pattern and the spatial stress state of each point in the space of the three-dimensional well pattern, calculate the active utilization coefficient of the stress field according to the size, position of the space, the weights of each zone in the space, and the proportion of the induced stress of each crack in the space on each point in the space, and quantitatively evaluate the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field, thereby realizing the quantitative evaluation of the active utilization effect of the spatial stress field and improving the evaluation accuracy. Description of the Drawings

[0041] To more clearly illustrate the technical solutions in the embodiments of this article or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of this article. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0042] Figure 1 The figure shows a schematic diagram of the implementation system of an evaluation method for the active utilization effect of the spatial stress field of a three-dimensional well pattern in an embodiment of this article;

[0043] Figure 2 The figure shows a flowchart of an evaluation method for the active utilization effect of the spatial stress field of a three-dimensional well pattern in an embodiment of this article;

[0044] Figure 3 The figure shows the process of partitioning the space according to the Mohr circle envelope and the spatial stress state of each point in the space of a three-dimensional well pattern in an embodiment of this article;

[0045] Figure 4 The figure shows the process of classifying each point into a fracture zone, a potential zone for network fracture formation, a potential zone for simple fracture formation, or a non-fracture potential zone according to the overlapping area of the Mohr circles and the Mohr circle envelope of each point in the space in an embodiment of this article;

[0046] Figure 5 The figure shows a schematic diagram of the structure of an evaluation device for the active utilization effect of the spatial stress field of a three-dimensional well pattern in an embodiment of this article;

[0047] Figure 6 The figure shows a schematic diagram of the Mohr circle envelope in an embodiment of this article;

[0048] Figure 7 The figure shows a schematic diagram of the structure of a computer device in an embodiment of this article.

[0049]

Explanation of the reference numerals

[0050] 101, horizontal well;

[0051] 102, fracture;

[0052] 501, Mohr circle envelope acquisition unit;

[0053] 502, spatial stress field partitioning unit;

[0054] 503, active utilization coefficient calculation unit of the stress field;

[0055] 504, quantitative evaluation unit of the active utilization effect of the spatial stress field;

[0056] 702, computer device;

[0057] 704. Processing device;

[0058] 706. Storage resource;

[0059] 708. Driving mechanism;

[0060] 710. Input / output module;

[0061] 712. Input device;

[0062] 714. Output device;

[0063] 716. Rendering device;

[0064] 718. Graphical user interface;

[0065] 720. Network interface;

[0066] 722. Communication link;

[0067] 724. Communication bus. Detailed implementation manners

[0068] Next, the technical solutions in the embodiments of the present disclosure will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present disclosure.

[0069] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above accompanying drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, device, product or equipment including a series of steps or units does not necessarily need to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or equipment.

[0070] As Figure 1 shown is a schematic diagram of an implementation system of an evaluation method for the active utilization effect of the spatial stress field of a three-dimensional well pattern in an embodiment of the present disclosure, including: horizontal well 101 and fracture 102, as Figure 1As shown in the figure, L is the well spacing between two horizontal wells 101 on the same horizontal plane, a is the half length of the fracture 102, and b is the half height of the fracture 102. Since tight oil and gas reservoirs generally have the characteristics of low porosity and low permeability, in the development process, large-scale hydraulic fracturing technology needs to be used to create large-scale fractures 102 on the horizontal wells 101, thereby increasing the matrix conductivity and achieving the purpose of improving resource utilization rate and recovery rate, and finally realizing efficient development. During the hydraulic fracturing process, a large amount of fracturing fluid and proppant need to be injected into the rock formation in a short time, thereby changing the stress state of the rock formation and causing rock fractures, and finally forming a connected fracture network structure in the space of the three-dimensional well pattern. At the same time, the large amount of injected fracturing fluid and proppant will generate induced stress around the fractures. When synchronous fracturing or zipper fracturing is carried out on multiple horizontal wells 101, the induced stresses generated by each fracture 102 will be superimposed on each other, forming a complex spatial stress field.

[0071] In order to evaluate the active utilization effect of the complex spatial stress field, the embodiments of this article provide an evaluation method for the active utilization effect of the spatial stress field of a three-dimensional well pattern, which can quantitatively evaluate the active utilization effect of the spatial stress field. Figure 2 As shown in the figure is a flowchart of an evaluation method for the active utilization effect of the spatial stress field of a three-dimensional well pattern in an embodiment of this article. The evaluation process of the active utilization effect of the spatial stress field of the three-dimensional well pattern is described in this figure, but based on routine or non-creative labor, it may include more or fewer operation steps. The order of steps listed in the embodiments is only one way among the execution orders of numerous steps and does not represent the only execution order. When the actual system or device product is executed, it can be executed sequentially or in parallel according to the method order shown in the embodiments or the drawings. Specifically, as Figure 2 shown, the method may include:

[0072] Step 201: Obtain the Mohr circle envelope applicable to the target layer rock based on a large number of indoor experiments on the target layer in the work area or empirical data of adjacent blocks;

[0073] Step 202: Divide the space according to the Mohr circle envelope and the spatial stress state of each point in the space of the three-dimensional well pattern. The spatial stress state is the superposition of the spatial induced stress of each fracture in the space on each point in the space and the original in-situ stress;

[0074] Step 203: Calculate the active utilization coefficient of the stress field according to the size, position of the space, the weight of each partition in the space, and the proportion of the induced stress of each fracture in the space on each point in the space;

[0075] Step 204: Quantitatively evaluate the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field.

[0076] Through the method of the embodiments of this article, the space is partitioned according to the Mohr circle envelope applicable to the rock of the target layer and the spatial stress state of each point in the three-dimensional well pattern space. The active utilization coefficient of the stress field is calculated according to the size, position of the space, the weights of each partition in the space, and the proportion of the induced stress of each fracture in the space to the stress of each point in the space. The active utilization effect of the spatial stress field is quantitatively evaluated according to the active and utilization coefficient of the stress field, realizing the quantitative evaluation of the active utilization effect of the spatial stress field, and thus improving the evaluation accuracy.

[0077] In the embodiments of this article, first, rock samples in the three-dimensional well pattern space whose active utilization effect is to be evaluated are obtained, and the Mohr circle envelope applicable to the rock of the target layer is obtained based on a large number of indoor experiments on the target layer in the work area or empirical data of adjacent blocks. The spatial stress field of the three-dimensional well pattern in the embodiments of this article includes the stress tensor of each point in the space of the three-dimensional well pattern, the maximum principal stress of each point, the minimum principal stress of each point, and the direction of the maximum principal stress of each point. In the embodiments of this article, based on the three-dimensional geophysical exploration data of the three-dimensional well pattern obtained on site, the spatial stress field can be obtained by using the numerical inversion method, or other methods in the prior art can also be used, such as establishing a three-dimensional geological mechanics model using industrial software and obtaining the spatial stress field by numerical solution methods, etc. There is no limitation in the embodiments of this specification.

[0078] The above Mohr circle envelope is obtained based on a large number of indoor experiments on the target layer or empirical data of adjacent blocks. There are various preferred rupture criteria for the Mohr circle envelope. The Mohr-Coulomb criterion is preferably used for conventional reservoirs, and the Mogi-Coulomb criterion is preferably used for shale reservoirs.

[0079] In the embodiments of this article, the spatial stress field also includes the superposition of the spatial induced stress of each fracture in the space and the original in-situ stress for each point in the space. Since the spatial induced stress of each fracture in the space changes with the injection of fracturing fluid into the fracture. The magnitude of the induced stress will determine whether each point in the space will fracture. In the current prior art, the influence of the magnitude of the induced stress on each point in the space only includes fracture initiation and non-fracture initiation.

[0080] According to an embodiment of this article, in order to increase the evaluation accuracy of the active utilization effect of the spatial stress field, the partitioning in step 202 further includes a fracture zone, a reticular fracture formation potential zone, a simple fracture formation potential zone, and a non-fracture potential zone.

[0081] In the embodiments of the present invention, the space is divided into a fracture zone, a reticulated fracture formation potential zone, a simple fracture formation potential zone, and a non-fracture potential zone according to the Mohr circle envelope and the spatial stress state of each point in the space. Among them, the fracture zone indicates that a fracture has been formed at this point. The reticulated fracture formation zone indicates that due to the action of the induced stress, a network of fractures will be formed at this point, and the reticulated fractures indicate that the number of fractures to be formed at this point is greater than or equal to [number of fractures]. The simple fracture formation zone indicates that due to the action of the induced stress, a simple fracture will be formed at this point, and the simple fracture indicates that the number of fractures to be formed at this point is 1. The non-fracture potential zone indicates that even with the action of the induced stress, no fractures will be formed at this point.

[0082] According to one embodiment of the present invention, the Mohr circle envelope described in step 201 may be as Figure 6 shown, in Figure 6 , the abscissa of the Mohr circle envelope is the normal stress σ, and the ordinate is the shear stress τ.

[0083] According to one embodiment of the present invention, as Figure 3 shown, step 202 further includes

[0084] Step 301: Calculate the horizontal maximum principal stress, horizontal minimum principal stress, and vertical stress of each point according to the spatial stress state of each point in the space;

[0085] Step 302: Calculate the overlapping area of the Mohr circles of each point according to the horizontal maximum principal stress, horizontal minimum principal stress, and vertical stress;

[0086] Step 303: Divide each point in the space into the fracture zone, the reticulated fracture formation potential zone, the simple fracture formation potential zone, or the non-fracture potential zone according to the overlapping area of the Mohr circles of each point in the space and the Mohr circle envelope.

[0087] In the embodiments of the present invention, the spatial stress field of each point can be calculated by formula (1),

[0088]

[0089] In formula (1), σ uni is the spatial stress field, σ xx,uni is the stress component of the spatial stress field in the x direction of the space, σ yy,uni is the stress component of the spatial stress field in the y direction of the space, σ zz,uni is the stress component of the spatial stress field in the z direction of the space, τ xy,uni is the shear stress of the spatial stress field in the x0y plane, τ xz,uni is the shear stress of the spatial stress field in the x0z plane, τ yz,uniis the shear stress of the spatial stress field in the y0z plane, i represents the i-th crack in the space, n represents the number of cracks in the space, and σ zz is the stress component in the z direction of the induced stress field of the crack in the space, and σ xx is the stress component in the x direction of the induced stress field of the crack in the space, and σ yy is the stress component in the y direction of the induced stress field of the crack in the space, and τ xy is the shear stress of the induced stress field of the crack in the x0y plane, and τ yz is the shear stress of the induced stress field of the crack in the y0z plane, and τ xz is the shear stress of the induced stress field of the crack in the x0z plane, and σ xF is the stress component in the x direction of the original in-situ stress field in the space, and σ yF is the stress component in the y direction of the original in-situ stress field in the space, and σ zF is the stress component in the z direction of the original in-situ stress field in the space, where x, y, and z are the coordinates of a certain point in the space. Among them, the induced stress state of each point can be measured by measuring instruments, and the embodiments of this specification do not make restrictions.

[0090] The eigenvalues of the stress matrix can be obtained according to the spatial stress field σ uni and the method of elastoplastic mechanics to obtain the maximum horizontal principal stress, minimum horizontal principal stress, and vertical stress. Preferably, the embodiments herein also provide a simplified method for calculating the maximum horizontal principal stress, minimum horizontal principal stress, and vertical stress, which can specifically be calculated through formulas (2)-(4).

[0091]

[0092]

[0093] σ C = σ zz,uni (4)

[0094] Among them, σ A represents the maximum horizontal principal stress, σ B represents the minimum horizontal principal stress, and σ C represents the vertical stress.

[0095] Among them, the method for calculating the overlapping area of the Mohr circles of each point according to the maximum horizontal principal stress, minimum horizontal principal stress, and vertical stress in step 302 includes

[0096] Sort the maximum horizontal principal stress, minimum horizontal principal stress, and vertical stress in descending order, and denote the maximum value as σ 1,uni , the middle value as σ2,uni , the minimum value is denoted as σ 3,uni , for example, if σ A >σ C >σ B , then σ 1,uni = σ A , σ 2,uni = σ C , σ 3,uni = σ B ;

[0097] As Figure 6 shown, first, calculate the coordinates of points O1, O2, and O3 according to σ 1,uni , σ 2,uni , σ 3,uni . Specifically, the calculation formula is as shown in formula (5),

[0098]

[0099] Then, with O1 as the origin, draw a semi - circle A with σ 2,uni - σ 3,uni as the diameter. With O3 as the origin, draw a semi - circle B with σ 1,uni - σ 2,uni as the diameter. With O2 as the origin, draw a semi - circle C with σ 1,uni - σ 3,uni as the diameter. The shaded area enclosed by arcs A, B, and C is the overlapping area of the Mohr circles.

[0100] According to an embodiment, as Figure 4 shown, step 303 divides each point in the space into the crack zone, the reticulated seam formation potential zone, the simple seam formation potential zone, or the non - crack potential zone according to the overlapping area of the Mohr circles of each point in the space and the Mohr circle envelope line, including

[0101] Step 401: Compare the shear stress corresponding to each normal stress in the overlapping area of the Mohr circles with the shear stress corresponding to this normal stress in the Mohr circle envelope line;

[0102] Step 402: If there is at least one shear stress T1 corresponding to a normal stress in the overlapping area of the Mohr circles of a certain point that is greater than the shear stress T2 corresponding to this normal stress in the Mohr circle envelope line, and the difference between the shear stress T1 and the shear stress T2 is greater than the preset range, then this point belongs to the crack zone;

[0103] Step 403: If the shear stress T1 corresponding to all normal stresses in the overlapping area of the Mohr circles of a certain point is less than the shear stress T2 corresponding to all these normal stresses in the Mohr circle envelope line, and the difference between the shear stress T2 and the shear stress T1 is greater than the preset range, then this point belongs to the non - crack potential zone;

[0104] Step 404: If the maximum shear stress T1 in the overlapping area of the Mohr circles at a certain point is greater than or equal to the shear stress T2 corresponding to the normal stress of this maximum shear stress T1 in the Mohr circle envelope, and the difference between the maximum shear stress T1 and the shear stress T2 is less than or equal to a preset range, or, if the maximum shear stress T1 in the overlapping area of the Mohr circles at a certain point is less than the shear stress T2 corresponding to the normal stress of this maximum shear stress T1 in the Mohr circle envelope, and the difference between the shear stress T2 and the maximum shear stress T1 is less than or equal to a preset range, then calculate the horizontal stress difference coefficient at this point according to the spatial stress state of this point;

[0105] Step 405: If the horizontal stress difference coefficient at this point is less than a preset threshold value, then this point belongs to the potential area of network fracture formation;

[0106] Step 406: If the horizontal stress difference coefficient at this point is greater than or equal to the preset threshold value, then this point belongs to the potential area of simple fracture formation.

[0107] Specifically, as Figure 6 shown, the shaded part represents the overlapping area of the Mohr circles at a certain point in space. The abscissa of the overlapping area of the Mohr circles is the normal stress σ, and the ordinate is the shear stress τ. Then, compare the overlapping area of the Mohr circles with the Mohr circle envelope. If there is at least one shear stress T1 corresponding to the normal stress in the overlapping area of the Mohr circles that is greater than the shear stress T2 of this normal stress in the Mohr circle envelope, and the difference between the shear stress T1 and the shear stress T2 is greater than the preset range △, that is, the shaded part of the overlapping area of the Mohr circles exceeds the range of △ above the Mohr circle envelope, then this point belongs to the fracture area, which means that a fracture has been formed at this point;

[0108] If the shear stress T1 of all normal stresses in the overlapping area of the Mohr circles is less than the shear stress T2 corresponding to all these normal stresses in the Mohr circle envelope, and the difference between the shear stress T2 and the shear stress T1 is greater than the preset range △, that is, the shaded part of the overlapping area of the Mohr circles is less than the range of △ below the Mohr circle envelope, then this point belongs to the non-fracture potential area, which means that a fracture will not be formed at this point;

[0109] If the maximum shear stress T1 in the overlapping area of the Mohr circles is greater than or equal to the shear stress T2 corresponding to the normal stress of this maximum shear stress T1 in the Mohr circle envelope, and the difference between the maximum shear stress T1 and the shear stress T2 is less than or equal to the preset range △, or, if the maximum shear stress T1 in the overlapping area of the Mohr circles is less than the shear stress T2 corresponding to the normal stress of this maximum shear stress T1 in the Mohr circle envelope, and the difference between the shear stress T2 and the maximum shear stress T1 is less than or equal to the preset range △, that is, the maximum shear stress in the shaded part of the overlapping area of the Mohr circles is within the range of △ above and below the Mohr circle envelope, then calculate the horizontal stress difference coefficient at this point according to the spatial stress state of this point.

[0110] Specifically, the horizontal stress difference coefficient at this point is calculated by formula (6).

[0111]

[0112] where ε represents the horizontal stress difference coefficient, and σ A 、σ B are calculated through formulas (2)-(4) in this specification.

[0113] If the horizontal stress difference coefficient at this point is less than the preset threshold value, this point belongs to the reticulated fracture formation potential area. If the horizontal stress difference coefficient at this point is greater than or equal to the preset threshold value, this point belongs to the simple fracture formation potential area

[0114] In the embodiments herein, preferably, the preset range △ is 5% of the shear stress T2. The preset threshold value varies according to different strata and can be determined through laboratory tests or numerical simulations. Preferably, the preset threshold value is 0.3.

[0115] According to an embodiment herein, the formula for calculating the stress field active utilization coefficient in step 203 based on the size of the space, the weights of each partition in the space, and the proportion of the induced stress of each fracture in the space on each point in the space is

[0116]

[0117] where W represents the stress field active utilization coefficient, represents the three-dimensional space from the target area x1 to x n , y1 to y n , z1 to z n in the space. △x, △y, △z are the grid unit lengths in three directions. n represents the number of grids divided in the x, y, and z directions of the space. φ represents the weight of the partition. k represents the number of partitions. γ represents the proportion of the induced stress. m represents the number of those ranked in the top in the descending order of the proportion of the induced stress;

[0118] In the embodiments herein, the number of partitions k is 4, which are the fracture area S1(x, y, z), the reticulated fracture formation potential area S2(x, y, z), the simple fracture formation potential area S3(x, y, z), and the non-fracture potential area S4(x, y, z) respectively. Where x, y, z are the coordinates of a certain point in the space. The weight of the fracture area S1(x, y, z) is denoted as φ1, the weight of the reticulated fracture formation potential area S2(x, y, z) is denoted as φ2, the weight of the simple fracture formation potential area S3(x, y, z) is denoted as φ3, and the weight of the non-fracture potential area S4(x, y, z) is denoted as φ4. In the embodiments herein, φ1 = 3, φ2 = 2, φ3 = 1, φ4 = 0.

[0119] The calculation formula for the proportion of the induced stress is as follows:

[0120]

[0121] where γ represents the proportion of the induced stress, σ j (x,y,z) represents the spatial induced stress of the j-th crack in the space on the points with x, y, and z coordinates, and n represents the number of cracks in the space.

[0122] In the embodiments of this article, represents the superimposed stress field of n cracks in the space, which can be calculated by formula (9),

[0123]

[0124] where i represents the crack number, n represents the number of cracks in the space, σ zz is the stress component of the induced stress field of the crack in the z direction of the space, σ xx is the stress component of the induced stress field of the crack in the x direction of the space, σ yy is the stress component of the induced stress field of the crack in the y direction of the space, τ xy is the shear stress of the induced stress field of the crack in the x0y plane, τ yz is the shear stress of the induced stress field of the crack in the y0z plane, τ xz is the shear stress of the induced stress field of the crack in the x0z plane.

[0125] It should be noted that the tensor components of each crack are all expressed in the global unified coordinate system. If it is the local coordinate system of a single crack, the respective origin and coordinate axis directions need to be unified to the global unified coordinate system through methods such as coordinate translation and rotation transformation before participating in the calculation.

[0126] In the embodiments of this article, the proportion of the induced stress is defined as the proportion of the induced stress of any nearby crack to the sum of the spatial stresses at this point. First, calculate the proportion of the induced stress of all cracks in the space to this point, and then sort the proportions from large to small. For example: taking the point (x, y, z) in the global coordinate system as an example, the proportions of the induced stresses of the cracks with the greatest influence (assumed to be the j-th crack) and the second greatest influence (assumed to be the k-th crack) are respectively

[0127] In the embodiments of this article, the number m of the top-ranked ones in the descending order ranking of the proportion of the induced stress is preferably 5.

[0128] According to an embodiment of this article, step 204 further includes quantitatively evaluating the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field as follows:

[0129] Evaluate the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field and a preset threshold value of the active utilization coefficient.

[0130] In the embodiments of the present invention, the active utilization coefficient W of the stress field is an important parameter for quantitatively evaluating the active utilization effect of the dynamic stress field of a three-dimensional well pattern. The greater the influence of other fracture-induced stresses, the greater the number of fractures, and the greater the area of the potential fracture network formation area, the greater the active utilization coefficient W of the stress field. The threshold value of the active utilization coefficient can be determined according to the fracturing conditions and production efficiency of individual wells in the three-dimensional well pattern. Optionally, first, according to the economic production index, determine the ultimate recoverable reserves of an individual well in the space of the three-dimensional well pattern, calculate the spatial stress field of adjacent wells in the three-dimensional well pattern by obtaining the fracturing conditions of adjacent wells, calculate the active utilization coefficient of the stress field according to the spatial stress field, and finally determine the threshold value of the active utilization coefficient according to the active utilization coefficient of the stress field and the ultimate recoverable reserves of the individual well. When the active utilization coefficient W of the stress field is greater than the preset threshold value of the active utilization coefficient, it indicates that the active utilization effect of the spatial stress field meets the requirements.

[0131] Based on the same inventive concept, the embodiments of the present specification also provide an evaluation device for the active utilization effect of the spatial stress field of a three-dimensional well pattern, as Figure 5 shown, including a Mohr circle envelope acquisition unit 501, a spatial stress field partitioning unit 502, a stress field active utilization coefficient calculation unit 503, and a spatial stress field active utilization effect quantitative evaluation unit 504:

[0132] The Mohr circle envelope acquisition unit 501 is configured to obtain a Mohr circle envelope applicable to the target layer rock based on a large number of indoor experiments on the target layer in the work area or empirical data of adjacent blocks;

[0133] The spatial stress field partitioning unit 502 is configured to partition the space according to the Mohr circle envelope and the spatial stress state of each point in the space of the three-dimensional well pattern, where the spatial stress field includes the superposition of the spatial induced stress of each fracture in the space on each point in the space and the original in-situ stress;

[0134] The stress field active utilization coefficient calculation unit 503 is configured to calculate the stress field active utilization coefficient according to the size, position of the space, the weights of each partition in the space, and the proportion of the induced stress of each fracture in the space on each point in the space;

[0135] The spatial stress field active utilization effect quantitative evaluation unit 504 is configured to quantitatively evaluate the active utilization effect of the spatial stress field according to the stress field active utilization coefficient.

[0136] The beneficial effects achieved by the above device are the same as those achieved by the above method, and the embodiments of the present specification will not elaborate.

[0137] As shown Figure 7 in the structural schematic diagram of the computer device according to the embodiment of the present invention, the evaluation device for the active utilization effect of the three-dimensional well pattern space stress field in the present invention can be the computer device in this embodiment to execute the method in the present invention above. The computer device 702 may include one or more processing devices 704, such as one or more central processing units (CPUs), and each processing unit may implement one or more hardware threads. The computer device 702 may also include any storage resource 706 for storing any kind of information such as code, settings, data, etc. Non-limiting, for example, the storage resource 706 may include any one or more combinations of the following: any type of RAM, any type of ROM, flash memory devices, hard disks, optical discs, etc. More generally, any storage resource may use any technology to store information. Further, any storage resource may provide volatile or non-volatile retention of information. Further, any storage resource may represent a fixed or removable component of the computer device 702. In one case, when the processing device 704 executes the associated instructions stored in any storage resource or combination of storage resources, the computer device 702 may perform any operation of the associated instructions. The computer device 702 also includes one or more drive mechanisms 708 for interacting with any storage resource, such as a hard disk drive mechanism, an optical disc drive mechanism, etc.

[0138] The computer device 702 may also include an input / output module 710 (I / O) for receiving various inputs (via the input device 712) and for providing various outputs (via the output device 714)). A specific output mechanism may include a presentation device 716 and an associated graphical user interface (GUI) 718. In other embodiments, the input / output module 710 (I / O), the input device 712, and the output device 714 may not be included, and it may only be a computer device in the network. The computer device 702 may also include one or more network interfaces 720 for exchanging data with other devices via one or more communication links 722. One or more communication buses 724 couple the components described above together.

[0139] The communication link 722 may be implemented in any manner, for example, through a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. The communication link 722 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc. governed by any protocol or combination of protocols.

[0140] Corresponding to Figures 2-4In the method described above, an embodiment of the present disclosure also provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the above-mentioned method are performed.

[0141] An embodiment of the present disclosure also provides a computer-readable instruction, and when the processor executes the instruction, the program therein causes the processor to execute as Figures 2-4 the method shown.

[0142] It should be understood that in various embodiments of the present disclosure, the magnitudes of the serial numbers of the above processes do not mean the order of execution, and the order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present disclosure.

[0143] It should also be understood that in the embodiments of the present disclosure, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present disclosure generally represents an "or" relationship between the associated objects before and after.

[0144] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present disclosure.

[0145] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments, and will not be repeated herein.

[0146] In the several embodiments provided in the present disclosure, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed couplings or direct couplings or communication connections to each other can be indirect couplings or communication connections through some interfaces, devices, or units, and can also be electrical, mechanical, or other forms of connection.

[0147] The unit described as a separation component may or may not be physically separated. The component shown as a unit may or may not be a physical unit, that is, it may be located in one place or distributed across multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiments in this article.

[0148] In addition, each functional unit in the various embodiments in this article can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0149] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution in this article, in essence, or the part that contributes to the prior art, or all or part of this 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 for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments in this article. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0150] Specific embodiments are used in this article to elaborate on the principles and implementation manners of this article. The description of the above embodiments is only used to help understand the method and its core idea in this article; at the same time, for those of ordinary skill in the art, according to the idea in this article, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to this article.

Claims

1. An evaluation method for the active utilization effect of the spatial stress field of a three-dimensional well pattern, characterized in that, The method includes obtaining a Mohr circle envelope applicable to the rocks of the target layer based on a large number of indoor experiments on the target layer in the work area or empirical data of adjacent blocks; dividing the space according to the Mohr circle envelope and the spatial stress state of each point in the space of the three-dimensional well pattern, where the spatial stress state is the superposition of the spatial induced stress of each fracture in the space on each point in the space and the original in-situ stress; calculating the active utilization coefficient of the stress field according to the size, position of the space, the weights of each partition in the space, and the proportion of the induced stress of each fracture in the space on each point in the space; quantitatively evaluating the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field; The formula for calculating the active utilization coefficient of the stress field according to the size, position of the space, the weights of each partition in the space, and the proportion of the induced stress of each fracture in the space on each point in the space is where W represents the active utilization coefficient of the stress field, represents the three-dimensional space in the said space, from the target area x1 to x n , from y1 to y n , from z1 to z n , Δx, Δy, Δz are the grid unit lengths in three directions, n represents the number of grids divided in the x, y, and z directions of the said space, φ represents the weight of the said partition, k represents the number of the said partitions, γ represents the proportion of the induced stress, and m represents the number of the top-ranked ones in the descending order of the proportion of the induced stress; where the formula for calculating the proportion of the induced stress is where γ represents the proportion of the induced stress, and σ j (x, y, z) represents the spatial induced stress of the j-th crack in the space on the points with x, y, and z coordinates, and n represents the number of cracks in the space.

2. The evaluation method for the active utilization effect of the spatial stress field of the three-dimensional well pattern according to claim 1, wherein The partitions include a fracture zone, a reticular fracture formation potential zone, a simple fracture formation potential zone, and a non-fracture potential zone.

3. The evaluation method for the active utilization effect of the spatial stress field of the three-dimensional well pattern according to claim 2, wherein Dividing the space according to the Mohr circle envelope and the spatial stress state of each point in the space of the three-dimensional well pattern further includes calculating the horizontal maximum principal stress, horizontal minimum principal stress, and vertical stress of each point according to the spatial stress state of each point in the space; calculating the overlapping area of the Mohr circles of each point according to the horizontal maximum principal stress, horizontal minimum principal stress, and vertical stress; dividing each point in the space into the fracture zone, the reticular fracture formation potential zone, the simple fracture formation potential zone, or the non-fracture potential zone according to the overlapping area of the Mohr circles of each point in the space and the Mohr circle envelope.

4. The evaluation method for the active utilization effect of the spatial stress field of the three-dimensional well pattern according to claim 3, characterized in that Dividing each point in the space into the fracture zone, the reticular fracture formation potential zone, the simple fracture formation potential zone, or the non-fracture potential zone according to the overlapping area of the Mohr circles of each point in the space and the Mohr circle envelope further includes comparing the shear stress corresponding to each normal stress in the overlapping area of the Mohr circles with the shear stress corresponding to this normal stress in the Mohr circle envelope; if there is at least one shear stress T1 corresponding to a normal stress in the overlapping area of the Mohr circles of a certain point that is greater than the shear stress T2 corresponding to this normal stress in the Mohr circle envelope, and the difference between the shear stress T1 and the shear stress T2 is greater than a preset range, then this point belongs to the fracture zone; if the shear stress T1 corresponding to all normal stresses in the overlapping area of the Mohr circles of a certain point is less than the shear stress T2 corresponding to all these normal stresses in the Mohr circle envelope, and the difference between the shear stress T2 and the shear stress T1 is greater than the preset range, then this point belongs to the non-fracture potential zone; If the maximum shear stress T1 in the overlapping area of the Mohr circles at a certain point is greater than or equal to the shear stress T2 corresponding to the normal stress of this maximum shear stress T1 in the Mohr circle envelope, and the difference between the maximum shear stress T1 and the shear stress T2 is less than or equal to a preset range, or, if the maximum shear stress T1 in the overlapping area of the Mohr circles at a certain point is less than the shear stress T2 corresponding to the normal stress of this maximum shear stress T1 in the Mohr circle envelope, and the difference between the shear stress T2 and the maximum shear stress T1 is less than or equal to the preset range, then calculate the horizontal stress difference coefficient at this point according to the spatial stress field at this point; If the horizontal stress difference coefficient at this point is less than the preset threshold value, then this point belongs to the reticular fracture formation potential area; If the horizontal stress difference coefficient at this point is greater than or equal to the preset threshold value, then this point belongs to the simple fracture formation potential area.

5. The evaluation method for the active utilization effect of the spatial stress field of the three-dimensional well pattern according to claim 4, characterized in that, The preset range is 5% of the shear stress T2.

6. The evaluation method for the active utilization effect of the spatial stress field of a three-dimensional well pattern according to claim 1, characterized in that, Quantitatively evaluating the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field further includes, Evaluating the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field and the preset threshold value of the active utilization coefficient.

7. An evaluation device for the active utilization effect of the spatial stress field of a three-dimensional well pattern, characterized in that, Including, A Mohr circle envelope acquisition unit, configured to acquire a Mohr circle envelope applicable to the rocks of the target layer based on a large number of indoor experiments on the target layer of the work area or empirical data of adjacent blocks; A spatial stress field partitioning unit, configured to partition the space according to the Mohr circle envelope and the spatial stress states of each point in the space of the three-dimensional well pattern, where the spatial stress field includes the superposition of the spatial induced stress and the original in-situ stress of each crack in the space on each point in the space; An active utilization coefficient calculation unit of the stress field, configured to calculate the active utilization coefficient of the stress field according to the size, position of the space, the weights of each partition in the space, and the proportion of the induced stress of each crack in the space on each point in the space; A quantitative evaluation unit for the active utilization effect of the spatial stress field, configured to quantitatively evaluate the active utilization effect of the spatial stress field according to the active utilization coefficient of the stress field; The formula for calculating the active utilization coefficient of the stress field according to the size, position of the space, the weights of each partition in the space, and the proportion of the induced stress of each crack in the space on each point in the space is, where W represents the active utilization coefficient of the stress field, represents the three-dimensional space in the said space, from the target area x1 to x n , from y1 to y n , from z1 to z n , △x, △y, △z are the grid unit lengths in three directions, n represents the number of grids divided in the x, y, and z directions of the said space, φ represents the weight of the said partition, k represents the number of the said partitions, γ represents the proportion of the induced stress, and m represents the number of those ranked among the top in the descending order of the proportion of the induced stress; Where the calculation formula for the proportion of the induced stress is, where γ represents the proportion of the induced stress, and σ j (x, y, z) represents the spatial induced stress of the j-th crack in the space on the points with x, y, and z coordinates, and n represents the number of cracks in the space.

8. A computer device, comprising a memory, a processor, and a computer program stored on the memory, characterized in that, When the computer program is run by the processor, it executes the instructions of the method according to any one of claims 1-6.

9. A computer storage medium, on which a computer program is stored, characterized in that, When the computer program is run by the processor of the computer device, it executes the instructions of the method according to any one of claims 1-6.

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