A method and device for active utilization of spatial stress field of a three-dimensional well pattern

Abstract

The application provides a stereoscopic well pattern space stress field active utilization method and device, including obtaining a plurality of fracturing schemes of a target well pattern; performing fracturing simulation on the target well pattern according to the fracturing schemes to determine a fracturing structure of the target well pattern, wherein the fracturing structure represents the number and shape of cracks in the target well pattern; determining a stress field active utilization coefficient and a fracture network complexity coefficient of the fracturing scheme according to the fracturing structure, wherein the stress field active utilization coefficient represents the stress field active utilization effect in the fracturing simulation process, and the fracture network complexity coefficient represents the proportion of the crack area in the fracturing simulation process; and selecting an optimal fracturing scheme according to the stress field active utilization coefficient and the fracture network complexity coefficient to fracture the target well pattern. Through the above method, the most sufficient fracturing scheme using the space stress field can be determined, and the optimal fracturing scheme can be selected through the product operation to guide the fracturing of the real target well pattern.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil exploration, and in particular to a method and device for active utilization of spatial stress field of a three-dimensional well pattern. BACKGROUND

[0002] In the exploitation of tight reservoirs represented by shale, large-scale hydraulic fracturing operations are required. The fracturing sequence significantly affects the fracturing effect. The key problem is the mutual interference of spatial stress field, for example, the induced stress of the first fracturing significantly affects the expansion of the fracture of the later fracturing. Or in synchronous fracturing, the induced stress of the two fractures affects the expansion of each other. A series of methods are usually used to avoid the influence of induced stress and reduce stress interference. However, the interference between wells is not necessarily negative for development. Under the condition of three-dimensional development, by arranging a three-dimensional well pattern and staggered fractures, the interference between wells is changed from passive to active, and the induced stress field between wells is used to create complex fractures, thereby improving the producing degree and recovery ratio between wells. In order to achieve this goal, a method and technology for active utilization of spatial stress field of a three-dimensional well pattern are needed. Through appropriate development parameters, the induced stress in the fracturing process is fully utilized, the volume of the region where the horizontal stress difference is reduced is expanded as much as possible, and the area of the region where the network fracture is generated is expanded, thereby laying a foundation for efficient development of tight reservoirs.

[0003] Therefore, it is an important problem to be solved to develop an optimal development plan, optimize the fracturing sequence, improve the well pattern reconstruction volume, and realize efficient development of crude oil. The difference between different development plans and fracturing sequences is large, so how to select the optimal plan to improve the oil recovery ratio becomes a problem to be solved. SUMMARY

[0004] In view of the above problems of the prior art, the purpose of the present application is to provide a method and device for active utilization of spatial stress field of a three-dimensional well pattern, so as to solve the problem that the oil recovery ratio is large in different exploitation ways in the prior art.

[0005] In order to solve the above technical problems, the specific technical scheme of the present application is as follows:

[0006] On the one hand, the present application provides a method for active utilization of spatial stress field of a three-dimensional well pattern, comprising:

[0007] obtaining a plurality of fracturing plans of a target well pattern;

[0008] performing fracturing simulation on the target well pattern according to the fracturing plans to determine a fracturing structure of the target well pattern, wherein the fracturing structure represents the number and morphology of fractures in the target well pattern;

[0009] According to the fracturing structure, a stress field active utilization coefficient and a fracture network complexity coefficient of the fracturing scheme are determined, wherein the stress field active utilization coefficient represents stress field active utilization effect in a fracturing simulation process, and the fracture network complexity coefficient represents a proportion of a fracture region in the fracturing simulation process.

[0010] According to the stress field active utilization coefficient and the fracture network complexity coefficient, an optimal fracturing scheme is selected to fracture the target well pattern.

[0011] In another aspect, a three-dimensional well pattern space stress field active utilization device is also provided, comprising:

[0012] An acquisition unit is configured to acquire a plurality of fracturing schemes of a target well pattern.

[0013] A structure determination unit is configured to perform fracturing simulation on the target well pattern according to the fracturing schemes, and determine a fracturing structure of the target well pattern, wherein the fracturing structure represents a number of fractures and a fracture morphology in the target well pattern.

[0014] A coefficient determination unit is configured to determine a stress field active utilization coefficient and a fracture network complexity coefficient of the fracturing scheme according to the fracturing structure, wherein the stress field active utilization coefficient represents stress field active utilization effect in a fracturing simulation process, and the fracture network complexity coefficient represents a proportion of a fracture region in the fracturing simulation process.

[0015] A scheme selection unit is configured to select an optimal fracturing scheme according to the stress field active utilization coefficient and the fracture network complexity coefficient, so as to fracture the target well pattern.

[0016] With the above technical solution, the target well pattern can be fractured according to a plurality of fracturing schemes, and different fracture distributions of the target well pattern under each fracturing scheme can be obtained through the influence of different fracturing schemes on the target well pattern, including a number of fractures and a fracture morphology. The stress field active utilization coefficient and the fracture network complexity coefficient of the target well pattern under the fracturing scheme are determined according to the number of fractures and the fracture morphology. The stress field active utilization coefficient represents stress field active utilization effect of the target well pattern under the fracturing scheme, and the fracture network complexity coefficient represents a proportion of a fracture region of the target well pattern under the fracturing scheme. The effect of the fracturing scheme is objectively evaluated through the above two coefficients, and the optimal fracturing scheme is selected to fracture the target well pattern through the optimal fracturing scheme.

[0017] In order to make the above and other purposes, features and advantages of the present text more obvious and easy to understand, the following describes a preferred embodiment, and the accompanying drawings are described in detail as follows. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present disclosure, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0019] Figure 1 The overall system diagram of the three-dimensional well pattern space stress field active utilization method is shown.

[0020] Figure 2 The step schematic diagram of the three-dimensional well pattern space stress field active utilization method is shown.

[0021] Figure 3 The schematic diagram of fracturing a space of an injection well in a target well pattern is shown.

[0022] Figure 4 The overall schematic diagram of fracturing of an injection well in a target well pattern is shown.

[0023] Figure 5 The stress field active utilization coefficient determination schematic diagram of the three-dimensional well pattern space stress field active utilization method is shown.

[0024] Figure 6 The Moire circle envelope area schematic diagram is shown.

[0025] Figure 7 The fracture network complexity coefficient determination schematic diagram of the three-dimensional well pattern space stress field active utilization method is shown.

[0026] Figure 8 The three-dimensional well pattern dynamic stress field active utilization device schematic diagram is shown.

[0027] Figure 9 The flowchart of the three-dimensional well pattern space stress field active utilization method is shown.

[0028] Figure 10 The computer device schematic diagram is shown.

[0029] Explanation of drawing symbols:

[0030] 101. Database; 102. Computing Server; 103. Control Terminal; 801. Acquisition Unit; 802. Structure Determination Unit; 803. Coefficient Determination Unit; 804. Scheme Selection Unit; 1002. Computer Equipment; 1004. Processing Equipment; 1006. Storage Resources; 1008. Drive Mechanism; 1010. Input / Output Module; 1012. Input Device; 1014. Output Device; 1016. Presentation Device; 1018. Graphical User Interface; 1020. Network Interface; 1022. Communication Link; 1024. Communication Bus. Detailed Implementation

[0031] The technical solutions in the embodiments described below will be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments described herein, and not all of the embodiments. Based on the embodiments described herein, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this document.

[0032] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings herein are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0033] like Figure 1 The diagram shown is an overall system diagram of a three-dimensional well network spatial stress field active utilization method according to an embodiment of this paper, including a database 101, a computing server 102 and a control terminal 103.

[0034] Database 101 is used to store geological data of the target well network, such as a large amount of indoor experimental data or experience data from adjacent blocks in the target layer of the target well network. This geological data reflects the basic physical properties of the target well network, including fracture data at each location, i.e., how much stress will cause a fracture.

[0035] Because the present application is suitable for the exploitation of unconventional reservoirs such as shale, the tight oil and gas reservoirs of shale type generally have low porosity and low permeability characteristics, and in the development process, large-scale hydraulic fracturing technology is required to create a large-scale artificial fracture network, thereby increasing the matrix conductivity, achieving the purpose of improving resource utilization and recovery, and ultimately achieving efficient development. Therefore, the database 101 also stores various ways of arranging injection wells in the prior art, as well as the injection time sequence of the injection wells.

[0036] The various ways of arranging injection wells and the injection time sequence of the injection wells can constitute a fracturing scheme.

[0037] The operation server 102 is used to receive control of the control terminal 103, and to perform operations on different fracturing schemes obtained from the database 101. When the operation server 102 receives an operation instruction, it obtains the technical and physical properties of the area where the target well pattern is located. Based on these physical properties, the operation server 102 can generate a Mohr circle envelope line suitable for the target well pattern. It should be noted that the operation server 102 can generate a Mohr circle envelope line according to the fracturing criterion. In order to reduce the length of this article, this article will not go into further detail, and those skilled in the art can obtain it themselves according to the prior art.

[0038] The operation server 102 sequentially calculates the number of fractures and the fracture morphology produced by each fracturing scheme acting on the target well pattern. The operation server 102 also calculates the initial stress field of the target well pattern according to the time sequence, i.e. the stress field at T = 0 under the time sequence. The specific calculation method will be described in detail below. The operation server 102 calculates the spatial stress field of the target well pattern under the fracturing scheme according to the initial stress field and the induced stress field caused by each fracture, and calculates the stress field active utilization coefficient and fracture network complexity coefficient of the target well pattern under the fracturing scheme by using the spatial stress field and the fracture direction at T = ∞ under the final time sequence, and sends them to the control terminal 103.

[0039] The control terminal 103 is used to display the stress field active utilization coefficient and fracture network complexity coefficient of each fracturing scheme. The control terminal 103 is configured with an operation function, which can add, multiply or mean square deviation the stress field active utilization coefficient and fracture network complexity coefficient to obtain a parameter that can represent the level of the stress field active utilization coefficient and fracture network complexity coefficient. The construction personnel can be informed to perform construction according to the fracturing scheme, and the actual effect of high fracturing degree can be obtained to enhance the development effect of the tight reservoir.

[0040] Tight oil and gas reservoirs are generally characterized by low porosity and low permeability. During development, large-scale hydraulic fracturing technology is used to create a large-scale artificial fracture network, thereby increasing the matrix conductivity, improving resource utilization and recovery, and ultimately achieving efficient development. During hydraulic fracturing, a large amount of fracturing fluid and proppant is injected into the rock formation in a short period of time, thereby changing the stress state of the rock formation and causing rock rupture, and ultimately forming a connected fracture network structure.

[0041] Meanwhile, a large amount of injected fracturing fluid and proppant will generate induced stress around the fractures. When multiple wells are simultaneously fractured or zipper fractured, the induced stresses generated by each fracture will superimpose on each other, forming a complex spatial stress. Currently known data believes that the stress interference caused by fracturing is negative: the stress between fractures near the wellbore is affected, which is easy to cause the complexity of the fracture to decrease, and form a simple single fracture; in the tensile stress zone at the tip of the fracture, if the fractures of two adjacent wells are too close, the fractures will be connected. If the well spacing is too small, the interwell interference caused by the fracturing of the adjacent well can even lead to the deformation of the wellbore. Therefore, in the current fracturing design process, the main idea is to avoid the interference problem of the spatial stress field during fracturing by expanding the well spacing, which ultimately leads to a small single-well recovery and low development efficiency.

[0042] To solve the above problems, the embodiments of the present application provide a three-dimensional well pattern spatial stress field active utilization method, which can select the optimal fracturing scheme from a plurality of fracturing schemes of a target well pattern, Figure 2 is a step schematic diagram of a three-dimensional well pattern spatial stress field active utilization method provided by the embodiments of the present application. The present specification provides method operation steps as described in the embodiments or flowcharts, but more or fewer operation steps can be included based on conventional or non-creative labor. The order of the steps listed in the embodiments is only one of the many execution orders, and does not represent the only execution order. In actual system or device product execution, the method order shown in the embodiments or the drawings can be executed in sequence or in parallel. Specifically, as shown in Figure 2 the method can include:

[0043] Step 201, obtaining a plurality of fracturing schemes of a target well pattern.

[0044] Step 202, performing fracturing simulation on the target well pattern according to the fracturing scheme, and determining the fracturing structure of the target well pattern, wherein the fracturing structure represents the number and morphology of the fractures in the target well pattern.

[0045] Step 203, determining the stress field active utilization coefficient and the fracture network complexity coefficient of the fracturing scheme according to the fracturing structure, wherein the stress field active utilization coefficient represents the stress field active utilization effect in the fracturing simulation process, and the fracture network complexity coefficient represents the proportion of the fracture area in the fracturing simulation process.

[0046] Step 204, according to the stress field active utilization coefficient and the fracture network complexity coefficient, selecting the optimal fracturing scheme to make the target well network fracturing.

[0047] According to the above technical solution, the target well network can be simulated by multiple fracturing schemes, and the different fracture distributions of the target well network under each fracturing scheme can be obtained through the influence of different fracturing schemes on the target well network, including the number of fractures and the fracture morphology. The stress field active utilization coefficient and the fracture network complexity coefficient of the target well network under the fracturing scheme are determined according to the number of fractures and the fracture morphology, the stress field active utilization coefficient is used to represent the stress field active utilization effect of the target well network under the fracturing scheme, and the fracture network complexity coefficient is used to represent the proportion of the fracture area of the target well network under the fracturing scheme. The effect of the fracturing scheme is objectively evaluated through the above two coefficients, the optimal fracturing scheme is selected, and the target well network is fractured by the optimal fracturing scheme.

[0048] As an embodiment of the present document, step 201 obtains several fracturing schemes of the target well network and step 202 simulates the fracturing of the target well network according to the fracturing scheme to determine the fracturing structure of the target well network, wherein the fracturing structure represents the number of fractures and the fracture morphology in the target well network. Specifically, it includes:

[0049] In the embodiment of the present document, before the fracturing simulation, a plurality of fracturing schemes of the target well network are designed, which include a plurality of primary fractures (main fractures) and the fracturing timing of each fracture. The fracturing timing specifies the fracturing time of each primary fracture. The liquid injection amount changes with time in each fracturing scheme, that is, the fracturing fluid flow rate of each fracturing scheme is different, so different fracturing schemes will produce different fracturing effects.

[0050] When performing fracturing, one of the fracturing schemes is selected and the liquid injection amount-time curve in the fracturing scheme is determined, and the fracturing fluid is injected into the horizontal wellbore to perform fracturing according to the liquid injection amount-time curve. With the injection of the fracturing fluid, the fracture tip of the primary fracture forms a secondary fracture, after the secondary fracture is formed, the fracturing fluid is injected into the secondary fracture, and then the tip of the secondary fracture can still form a next level of secondary fracture, and the primary fracture and the secondary fractures at all levels generate induced stresses in the horizontal well pattern space, the induced stresses generated by the primary fracture and the secondary fractures at all levels are superimposed on each other, and the spatial stress field at a certain moment can be obtained according to the induced stress at the moment, therefore, the spatial stress field at each moment is obtained by simulating the fracture propagation of the multiple secondary fractures, and the stress field active utilization coefficient at the moment is calculated according to the spatial stress field at the moment, therefore, the curve of the stress field active utilization coefficient changing with time can be obtained according to the sequence of each moment and the corresponding spatial stress field at each moment, and finally the active utilization effect of the dynamic stress field is quantitatively evaluated in real time according to the curve of the stress field active utilization coefficient changing with time.

[0051] Figure 3 The figure shows a schematic diagram of fracturing a certain space of the injection well in the target well pattern, including: a target well pattern 301, a horizontal wellbore 302, and a fracturing fluid 303. Because the tight oil and gas reservoirs generally have low porosity and low permeability characteristics, during the development process, large-scale hydraulic fracturing technology is needed to inject a large amount of fracturing fluid 303 into the horizontal wellbore 302, so as to create large-scale primary fractures 304 and secondary fractures 305 on the three-dimensional well pattern, thereby increasing the matrix conductivity. It should be noted that the primary fracture 304 is determined by the size, position and drilling method of the horizontal wellbore 302, that is, when the fracturing fluid 303 is not injected into the horizontal wellbore 302, the fracture that appears is the primary fracture 304, and after water injection into the primary fracture 304 through the horizontal wellbore 302, the fracture formed at the tip of the primary fracture 304 is the secondary fracture 305.

[0052] Figure 4 The figure shows a schematic diagram of the whole fracturing of the injection well in the target well pattern, in which 401, 402, 403, 404, 405 and 406 are all fracture areas, where a and b represent the size of the fracture area, and L is the distance between adjacent wells. The fracture area includes primary fractures and secondary fractures. It can be seen that the fracturing scheme in this paper is staggered arrangement. After the primary fracture is formed in the target well pattern, the original stress field of the target well pattern can be calculated according to the horizontal stress and vertical stress of the primary fracture to improve the resource utilization rate and recovery rate, and finally to achieve efficient development.

[0053] In the hydraulic fracturing process, the fracture propagation simulation can be performed according to the fracturing parameters of the primary fracture and the injection rate-time curve, the stress field-fracture network state coupling iteration method is used to simulate the fracture propagation of the secondary fracture, and the spatial stress field at each time in the three-dimensional well network space is obtained. In the embodiment of the present application, when the primary fracture is fractured, a fracturing scheme of the target well network is selected and the injection rate-time curve, i.e. the time sequence, in the fracturing scheme is determined, and the fracturing fluid is injected into the horizontal wellbore for fracturing according to the injection rate-time curve. With the injection of the fracturing fluid, the fracture tip of the primary fracture will form a secondary fracture. After the secondary fracture is formed, the fracturing fluid is injected into the secondary fracture. Then the tip of the secondary fracture can still form a next level of secondary fracture. When it is determined that the next level of secondary fracture will occur, the fracturing fluid is continuously injected into the secondary fracture until no secondary fracture occurs in the target well network. The induced stress generated by the primary fracture and the secondary fracture is calculated. The primary fracture and the secondary fracture will generate induced stress in the horizontal well network space, and the spatial stress field at T=∞ in the time sequence is calculated.

[0054] Because different fracturing schemes correspond to different time sequences, the spatial stress field generated by the initial stress field and the induced stress field in the target well network under different fracturing schemes is also different. In the subsequent embodiment of the present application, how to calculate the spatial stress field active utilization coefficient and the calculation method of the fracture network complexity coefficient under different fracturing schemes will be described.

[0055] In the embodiment of the present application, a scheme for simulating the fracture propagation of the target well network according to the time sequence of the pressure scheme can be provided.

[0056] Before simulating the fracture propagation of the secondary fracture, the spatial stress field at the initiation time of the primary fracture is first calculated according to the fracture length, fracture width, fracture height of the primary fracture, the induced stress field of all the fractures existing in the space at this time, and the superposition of the original stress. As an option, the time when the fracturing fluid fills the primary fracture can be calculated according to the injection rate-time curve and the fracture length, fracture width and fracture height of the primary fracture. When the fracturing fluid fills the primary fracture, the stress state of each measuring point in the space is recorded, and the spatial stress field of the primary fracture is obtained by interpolation.

[0057] First, it is judged whether each primary fracture forms a secondary fracture. If the primary fracture forms a secondary fracture, the time when the fracturing fluid fills the primary fracture is the initiation time of the secondary fracture. Specifically, the time required for the fracturing fluid to fill the primary fracture can be calculated by the flow balance method, as shown in formula (1),

[0058]

[0059] Wherein, Δt is the time required for the fracturing fluid to fill the primary fracture, l is the fracture length, b is the half fracture height, δ is the fracture width, and Q is the flow rate of the fracturing fluid.

[0060] Then, the spatial stress field at the initiation time of the secondary fracture is calculated and updated, which includes calculating the spatial stress field of the secondary fracture and superimposing the spatial stress field of the secondary fracture into the spatial stress field at the initiation time of the secondary fracture to complete the updating of the spatial stress field at the initiation time of the secondary fracture.

[0061] In the embodiments herein, the primary fracture can form multiple secondary fractures, and preferably, the number of secondary fractures formed by the primary fracture in the embodiments herein is 2. After the primary fracture forms the secondary fracture, the secondary fracture is taken as a primary fracture, and then the fracture propagation simulation is performed again on the new primary fracture.

[0062] If the primary fracture does not form a secondary fracture, the fracture propagation simulation is ended.

[0063] As Figure 5 As shown in the stress field active utilization coefficient determination diagram of the spatial stress field active utilization method of the three-dimensional well pattern, step 203 determines the stress field active utilization coefficient of the fracturing scheme according to the fracturing structure, and specifically includes:

[0064] Step 501: obtaining a Mohr circle envelope suitable for the target well pattern based on a large number of indoor experiments or experience data of adjacent blocks of the target well pattern.

[0065] It should be noted that the Mohr circle envelope is an objective analysis means for describing the formation where the target well pattern is located, and the Mohr circle envelope can represent the geological conditions of the formation where the target well pattern is located. Specifically, at a certain position, how much fracturing fluid is applied to make the rock break. Similarly, as some alternative means, the formation where the target well pattern is located can also be judged by the Coulomb criterion, or for shale, the Mogi-Coulomb criterion can be selected for judgment.

[0066] Step 502: determining the spatial stress field of each point in the target well pattern according to the fracturing structure.

[0067] including determining the average pressure in the fracture according to the size of the fracture and the fluid pressure at the tip and root of the fracture;

[0068] Further, the formula for calculating the average pressure in the fracture according to the fracture length, fracture width and fracture height is (2)-(3).

[0069]

[0070] Wherein, p1 is the fluid pressure at the tip of the fracture, p wfwherein Q is the fluid pressure at the root of the fracture, Q is the flow rate of the fracturing fluid, μ is the equivalent viscosity, l is the length of the fracture, h is the height of the fracture, δ is the width of the fracture, and p is the average pressure in the fracture.

[0071] determining an induced stress field of the fracture according to the size of the region, the size of the fracture, and the average pressure in the fracture;

[0072] calculating according to formulas (4)-(16)

[0073]

[0074]

[0075] wherein σ represents the induced stress field of the fracture, σ zz is the stress component of the induced stress field in the z direction of the region, p is the average pressure in the fracture, σ xx is the stress component of the induced stress field in the x direction of the region, σ yy is the stress component of the induced stress field in the y direction of the region, τ xy is the shear stress of the induced stress field in the x0y plane, τ yz is the shear stress of the induced stress field in the y0z plane, τ xz is the shear stress of the induced stress field in the x0z plane, μ is the equivalent viscosity, and x, y, z are the coordinates of a point in the region, is the half fracture length, is the half fracture height, and L, L1, L2, θ, θ1, θ2 are the calculation process variables.

[0076] superimposing the induced stress field of all the fractures in the target well pattern with the original ground stress field of the target well pattern to determine the spatial stress field of each point.

[0077] the spatial stress field in the target well pattern according to formula (17).

[0078]

[0079] wherein 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 target well pattern, σ yy,uni is the stress component of the spatial stress field in the y direction of the target well pattern, σ zz,uni is the stress component of the spatial stress field in the z direction of the target well pattern, 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 a shear stress of the spatial stress field in the x0y plane, i represents the i-th fracture in the target well pattern, n represents a number of fractures in the target well pattern, σ xF is a stress component of the original in-situ stress field in the x direction of the target well pattern, σ yF is a stress component of the original in-situ stress field in the y direction of the target well pattern, σ zF is a stress component of the original in-situ stress field in the z direction of the target well pattern.

[0080] Step 503, according to the Mohr circle envelope and the spatial stress field of each point in the target well pattern, the region where each point is located is divided into different types, wherein each point in the target well pattern represents the region attribute at the corresponding position, and the types of division include a fracture region, a network fracture potential region, a simple fracture potential region, and a non-fracture potential region, and specifically include:

[0081] In the embodiments herein, the division in step 503 further includes a fracture region, a network fracture potential region, a simple fracture potential region, and a non-fracture potential region, wherein the fracture region represents that the point has formed a fracture. The network fracture region represents that the point will form a network fracture due to the effect of the induced stress, and the network fracture represents that the number of fractures to be formed at the point is greater than or equal to n. The simple fracture potential region represents that the point will form a simple fracture due to the effect of the induced stress, and the simple fracture represents that the number of fractures to be formed at the point is 1. The non-fracture potential region represents that the point will not form a fracture even if there is an induced stress.

[0082] First, after the primary fracture is broken according to the time sequence, a secondary fracture is generated at the tip of the primary fracture, and the secondary fracture is continued to be broken as a primary fracture, and in this regard, the fracture region formed by the primary fracture and the secondary fracture includes four types, and among them, the network fracture is the optimal region, that is, the network fracture potential region.

[0083] Further, the horizontal maximum principal stress, the horizontal minimum principal stress, and the vertical stress of each point in the target well pattern are calculated respectively according to the spatial stress field of each point in the target well pattern.

[0084] Therefore, to calculate which type of fracture each fracture is located in, the horizontal maximum principal stress, the horizontal minimum principal stress, and the vertical stress of the tip of the primary fracture can be calculated by formulas (18)-(20),

[0085]

[0086] σ C = σ zz,uni (20)

[0087] wherein σ A represents the horizontal maximum principal stress, σB denotes the horizontal minimum principal stress, σ C denotes the vertical stress, x, y, z are the coordinates of the primary fracture tip in the spatial well pattern space, τ xy,uni denotes the shear stress of the spatial stress field of the primary fracture tip in the x0y plane, σ xx,uni is the stress component of the spatial stress field of the primary fracture tip in the x direction of the spatial well pattern space, σ yy,uni is the stress component of the spatial stress field of the primary fracture tip in the y direction of the spatial well pattern space, σ zz,uni is the stress component of the spatial stress field of the primary fracture tip in the z direction of the spatial well pattern space.

[0088] Further, the Mohr circle overlapping area of each point is calculated according to the horizontal maximum principal stress, the horizontal minimum principal stress and the vertical stress respectively.

[0089] The horizontal maximum principal stress, the horizontal minimum principal stress and the vertical stress are sorted in descending order, and the maximum value is recorded as σ 1,uni , the intermediate value is recorded as σ 2,uni , and the minimum value is recorded as σ 3,uni . For example, if σ A > σ C > σ B , then σ 1,uni = σ A , σ 2,uni = σ C , and σ 3,uni = σ B .

[0090] As shown in the Mohr circle envelope area schematic diagram, first, the coordinates of O1, O2, O3 points are calculated according to σ 1,uni , σ 2,uni , σ 3,uni , and the specific calculation formula is shown in formula (21),

[0091] O1 = (σ 2,uni + σ 3,uni ) / 2

[0092] O2 = (σ 1,uni + σ 3,uni ) / 2

[0093] O3 = (σ 2,uni + σ 1,uni ) / 2 (21)

[0094] Then draw a semicircle A with O1 as the origin and σ 2,uni - σ 3,uni as the diameter, and draw a semicircle B with O2 as the origin and σ 1,uni - σ 2,uni as the diameter.2,uni Draw a semicircle C with diameter O3, and σ 1,uni -σ 3,uni Draw a semicircle B with diameter, and get the shadow part of the circle arcs A, B, and C as the Moire circle overlap area.

[0095] Further, in the coordinate system, the contact position of the Moire circle overlap area of each point in the space and the preset range of the Moire circle envelope is determined.

[0096] In Figure 6 , the abscissa is the normal stress, and the ordinate is the shear stress. If the maximum shear stress T1 in the Moire circle overlap area where the tip of the primary crack is located is greater than or equal to the shear stress T2 corresponding to the normal stress of the maximum shear stress T1 in the Moire 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 Moire circle overlap area where the tip of the primary crack is located is less than the shear stress T2 corresponding to the normal stress of the maximum shear stress T1 in the Moire 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 the horizontal stress difference coefficient of the tip of the primary crack is calculated according to the spatial stress field of the tip of the primary crack. If the horizontal stress difference coefficient of the tip of the primary crack is less than the preset threshold value, then the tip of the primary crack forms a secondary crack, and the preset range is 5% of the shear stress T2.

[0097] Otherwise, the tip of the primary crack does not form a secondary crack.

[0098] Further, according to the contact position, each point in the space is partitioned.

[0099] In the embodiments herein, as Figure 6 shown, the shadow part represents the Moire circle overlap area of a certain point in the space, the abscissa of the Moire circle overlap area is the normal stress σ, and the ordinate is the shear stress τ. Then, the Moire circle overlap area and the Moire circle envelope are compared. If there is at least one shear stress T1 corresponding to the normal stress in the Moire circle overlap area that is greater than the shear stress T2 of the normal stress in the Moire circle envelope, and the difference between the shear stress T1 and the shear stress T2 is greater than the preset range Δ, that is, the shadow part of the Moire circle overlap area exceeds the Δ range above the Moire circle envelope, then the tip of the primary crack belongs to the crack region, that is, the tip of the primary crack forms a crack.

[0100] If all the shear stresses T1 of the normal stresses in the overlapping area of the Mohr's circles are less than the shear stresses T2 corresponding to the normal stresses in the envelope of the Mohr's circles, and the difference between the shear stress T2 and the shear stress T1 is greater than the preset range Δ, that is, the shadow part of the overlapping area of the Mohr's circles is less than the Δ range below the envelope of the Mohr's circles, then the tip of the primary crack belongs to the non-crack potential area, that is, the tip of the primary crack will not form a crack.

[0101] If the maximum shear stress T1 in the overlapping area of the Mohr's circles is greater than or equal to the shear stress T2 corresponding to the normal stress of the maximum shear stress T1 in the envelope of the Mohr's circles, and the difference between the maximum shear stress T1 and the shear stress T2 is less than or equal to the preset range Δ, or, if the maximum shear stress T1 in the overlapping area of the Mohr's circles is less than the shear stress T2 corresponding to the normal stress of the maximum shear stress T1 in the envelope of the Mohr's circles, and the difference between the shear stress T2 and the maximum shear stress T1 is less than or equal to the preset range Δ, that is, the maximum shear stress in the shadow part of the overlapping area of the Mohr's circles is within the Δ range above and below the envelope of the Mohr's circles, then the horizontal stress difference coefficient of the tip of the primary crack is calculated according to the spatial stress field of the tip of the primary crack.

[0102] Specifically, the horizontal stress difference coefficient of the tip of the primary crack is calculated by formula (22),

[0103]

[0104] If the horizontal stress difference coefficient of the tip of the primary crack is less than the preset threshold value, then the tip of the primary crack belongs to the net crack potential area, indicating that the tip of the primary crack forms a secondary crack, and if the horizontal stress difference coefficient of the tip of the primary crack is greater than or equal to the preset threshold value, then the tip of the primary crack belongs to the simple crack potential area, and then the length of the primary crack is re-estimated, and whether the tip of the primary crack belongs to the net crack potential area, that is, whether the tip of the primary crack will produce a secondary crack, is determined according to the re-estimated crack length. If the tip of the primary crack does not belong to the net crack potential area after repeatedly estimating the crack length, it is indicated that the primary crack cannot produce a secondary crack, and the tip of the primary crack is stable.

[0105] Step 504, weighting the crack area, the net crack potential area, the simple crack potential area and the non-crack potential area.

[0106] Since the utilization of the spatial stress field is different in different areas, in order to better reflect the utilization of the spatial stress field, the four areas are weighted in the embodiments, and the four areas are sequentially sorted from high to low in weight as the crack area, the net crack potential area, the simple crack potential area and the non-crack potential area according to the utilization effect.

[0107] Step 505, determining the stress field active utilization coefficient of the target well pattern according to the size and position of the region, the weight of each sub-area type in the target well pattern, and the induced stress proportion of each fracture in the target well pattern to each point in the space.

[0108] The stress field active utilization coefficient of the fracturing scheme is calculated according to formula (23)

[0109]

[0110] Wherein, W represents the stress field active utilization coefficient, represents the three-dimensional space of the target well pattern x1 to xn, y1 to yn, z1 to zn in the target well pattern, △x, △y, △z are the lengths of the regions in three directions, n represents the number of x, y, z division regions of the target well pattern, φ j represents the weight of the sub-area, k represents the number of each type of sub-area, γ represents the induced stress proportion, and m represents the threshold value of the descending order ranking of the induced stress proportion of the fractures in the region.

[0111] In the embodiments of the present application, the number of sub-areas k is 4, which are fracture area S1(x, y, z), network fracture potential area S2(x, y, z), simple fracture potential area S3(x, y, z) and non-fracture potential area S4(x, y, z), wherein x, y, z are the coordinates of a point in the target well pattern, the weight of the fracture area S1(x, y, z) is denoted as φ1, the weight of the network fracture potential area S2(x, y, z) is denoted as φ2, the weight of the simple fracture 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 of the present application, φ1=3, φ2=2, φ3=1, and φ4=0.

[0112] Wherein, the calculation formula of the induced stress proportion is

[0113]

[0114] Wherein, γ represents the induced stress proportion, σ j (x, y, z) represents the spatial induced stress of the jth fracture in the target well pattern to the point with x, y, z coordinates, and n represents the number of fractures in the space.

[0115] In the embodiments of the present application, represents the superimposed stress field of n fractures in the target well pattern, which can be calculated by formula (25)

[0116]

[0117] Wherein, i represents the fracture serial number, n represents the number of fractures in the space, σ zzσxxis the stress component of the induced stress field of the fracture in the x direction of the space xx σxxis the stress component of the induced stress field of the fracture in the x direction of the space yy τxyis the shear stress in the x0y plane of the induced stress field of the fracture xy τxyis the shear stress in the x0y plane of the induced stress field of the fracture yz τxyis the shear stress in the x0y plane of the induced stress field of the fracture xz τxyis the shear stress in the x0y plane of the induced stress field of the fracture

[0118] It should be noted that the tensor components of each fracture are all expressed in the global unified coordinate system, and if it is a local coordinate system of a single fracture, the origin and coordinate axis direction of each are unified to the global unified coordinate system through coordinate translation and rotation transformation methods before participating in the calculation.

[0119] In the embodiments of the present application, the induced stress ratio is defined as the ratio of the induced stress of any nearby fracture to the sum of the space stresses at the point. First, the induced stress ratio of each point in the space is calculated, and then the ratios are sorted from large to small. For example, taking the (x, y, z) point in the global coordinate system as an example, the induced stress ratios of the fracture with the greatest influence (assuming it is the jth fracture) and the second greatest influence (assuming it is the kth fracture) are formula (26) and formula (27) respectively.

[0120]

[0121] In the embodiments of the present application, the number m of the top-ranked in the descending order ranking of the induced stress ratio is preferably 5.

[0122] The stress field active utilization coefficient described above characterizes the stress field active utilization effect of each fracturing simulation process. In the embodiments of the present application, the horizontal wells are arranged in a staggered manner, the induced stress field is actively utilized to assist in generating a complex fracture network, the spatial positions of the main fractures are arranged skillfully, the tensile stress zones are staggered, the area of the low horizontal stress difference region is expanded, and the horizontal stress difference at the tip of the fracture is reduced due to the interference of the induced stress of the adjacent fracture, so that the fracture no longer expands to the wellbore of the adjacent well to cause shear deformation, but generates a complex fracture network under the action of the low horizontal stress difference.

[0123] Therefore, in order to more quantitatively represent the influence effect of the space stress field on the target well pattern, the induced stress of the adjacent fracture on the secondary fracture can also be considered to quantitatively calculate how many degrees each well deflects from T=0 to T=∞ to quantitatively describe the influence effect of the space stress field on each well. The following part shows how to calculate the deflection of the fracture, and each fracture is uniformly calculated to obtain the simulation fracturing result of the fracturing scheme.

[0124] For example,Figure 7 A fracture network complexity coefficient determination diagram of a stereoscopic well pattern space stress field active utilization method, as an embodiment of the present text, step 203 determines the fracture network complexity coefficient of the fracturing scheme, specifically including:

[0125] Step 701, respectively determine the fracture direction of each fracture in the target well pattern under the fracturing scheme.

[0126] Step 702, according to the angle between the fracture direction and the original stress field direction and the number of fractures in the space, determine the fracture network complexity coefficient.

[0127] The average value of the angle between all fracture planes and the direction of the maximum principal stress of the original stress field is the fracture network complexity coefficient described in the embodiments of the present text, which is actually the average value of all fracture directions and the direction of the maximum principal stress of the original stress field, that is, the degree of deviation from the horizontal maximum principal stress, which can represent the complexity of the fracture network. If the induced stress is fully utilized, the stress difference reduction area is formed at the tip of the main fracture, forming a complex fracture network, and an angle will be formed between the fracture direction and the direction of the main fracture of the original stress field. The larger the angle, the more severe the deflection, the better the fracturing effect, and the better the active utilization effect of the stress field. On the contrary, if all the fractures extend along the direction of the horizontal maximum principal stress of the original stress field, it means that the effect of making the fractures complex by utilizing the space-induced stress is not good, that is, the active utilization effect of the space stress field is not good. Therefore, the fracture network complexity coefficient calculated by the method described in the embodiments of the present text can also be used to evaluate the active utilization effect of the space stress field.

[0128] In addition, in some other embodiments of the present text, when the fractures in the stereoscopic well pattern space are divided into main fractures and secondary fractures, different weights can be assigned to the angles between the fracture directions of the main fractures and the secondary fractures and the direction of the maximum principal stress of the original stress field, respectively. Then, according to the angle between the fracture direction of the main fracture or the secondary fracture and the direction of the maximum principal stress of the original stress field, the weight of the angle, and the number of fractures, the fracture network complexity coefficient is calculated. The weight can be distributed according to the importance of the main fracture or the secondary fracture to the increase of oil and gas production, for example, the more important the main fracture or the secondary fracture to the increase of oil and gas production, the higher the weight of the main fracture or the secondary fracture. Through the above method, the fracture network complexity coefficient is calculated according to the importance of the fracture to the increase of oil and gas production, thereby further improving the accuracy of evaluating the active utilization effect of the space stress field.

[0129] As an embodiment of the present text, step 701 specifically includes:

[0130] Determining the type of each fracture under the fracturing scheme to determine the fracture direction, including:

[0131] When the crack is a tortuous crack, the horizontal maximum principal stress direction of each point on the crack path is calculated, and the average of the horizontal maximum principal stress directions of the points is taken as the crack direction of the crack.

[0132] When the crack is a straight crack, the horizontal maximum principal stress direction of the crack tip position of the crack is calculated, and the horizontal maximum principal stress direction of the crack tip position is taken as the crack direction of the crack.

[0133] Alternatively, determining the crack direction of each crack under the fracturing scheme comprises:

[0134] Obtaining the crack tip position and the crack initiation position of the crack, and determining the crack direction of the crack according to the direction of the crack tip position relative to the crack initiation position.

[0135] In the embodiments herein, the crack path of each crack in the target well pattern in the expansion process is affected by the spatial stress field formed by the superposition of the spatial induced stress of each point in the target well pattern by other cracks and the original ground stress, and therefore, the morphology of the crack can be a straight crack or a tortuous crack (i.e., the crack is expanded along a curved path).

[0136] Determining the type of each crack under the fracturing scheme determines the crack direction.

[0137] When the crack is a tortuous crack, it means that the crack direction of the crack in the expansion process is greatly affected by the spatial stress state of the spatial stress field at each point on the crack path, and the horizontal maximum principal stress direction of each point on the crack path is greatly different, resulting in the expansion of the crack in a tortuous morphology. Therefore, the horizontal maximum principal stress direction of each point on the crack path can be calculated according to the spatial stress state of the spatial stress field at each point on the crack path, and the average of the horizontal maximum principal stress directions of the points is taken as the crack direction of the crack.

[0138] When the crack is a straight crack, it means that the crack direction of the crack in the expansion process is less affected by the spatial stress state of the spatial stress field at each point on the crack path, and the horizontal maximum principal stress direction of each point on the crack path is not greatly different, so the crack expands in a straight line morphology. Therefore, only the horizontal maximum principal stress direction of the crack tip position of the crack needs to be calculated according to the spatial stress state of the spatial stress field at the crack tip position of the crack, and the horizontal maximum principal stress direction of the crack tip position is taken as the crack direction of the crack.

[0139] According to one embodiment herein, the formula for calculating the horizontal maximum principal stress direction is shown in (28),

[0140]

[0141] wherein θ uni denotes the direction of the maximum horizontal principal stress at a point on the fracture path, τ xy,uni denotes the shear stress in the x0y plane of the spatial stress state at a point on the fracture path, σ xx,uni denotes the stress component in the x direction of the spatial stress state at a point on the fracture path, σ yy,uni denotes the stress component in the y direction of the spatial stress state at a point on the fracture path, x, y denote the coordinates of a point on the fracture path in the target well pattern.

[0142] Similarly, when the fracture type cannot be determined, the fracture direction can be determined by the end point positions of each fracture under the fracturing scheme.

[0143] In the target well pattern, the direction of the fracture tip position relative to the fracture initiation position is calculated, and the direction of the fracture tip position relative to the fracture initiation position is taken as the fracture direction of the fracture.

[0144] As an embodiment herein, step 702 specifically comprises:

[0145] The sum of the angles between the fracture direction of each fracture and the direction of the original stress field is obtained to obtain an accumulated angle.

[0146] The accumulated angle is averaged according to the number of fractures in the target well pattern to determine the fracture network complexity coefficient of the target well pattern.

[0147] According to formula (29), the fracture network complexity coefficient of the target well pattern under the fracturing scheme can be obtained:

[0148]

[0149] wherein θ' denotes the fracture network complexity coefficient, denotes the angle between the fracture direction of the fracture on the fracture path of the i-th fracture and the direction of the maximum principal stress of the original stress field of the space, n denotes the number of fractures in the target well pattern.

[0150] If a complex fracture network structure forms between fractures in a three-dimensional well network, the fracture directions of each fracture are different, and the angles between the fracture directions and the direction of the maximum principal stress of the original geostress field are also different, meaning that each fracture extends in a different direction. Therefore, the larger the average value of the angles calculated by summing the angles and considering the number of fractures, the greater the degree to which each fracture extends outward in a divergent manner within the three-dimensional well network. Furthermore, the extension direction of each fracture is influenced by the spatial stress state of the spatial stress field of the three-dimensional well network at each point along its respective fracture path. Therefore, the fracture network complexity coefficient calculated according to the above steps can represent the active utilization effect of the spatial stress field of the three-dimensional well network. In this paper, it is desirable to obtain fracture-forming zones and potential fracture network zones. Increasing the probability of their occurrence is likely to improve the recovery rate of a single well. Therefore, the fracture network complexity coefficient is used to represent the proportion of fractured areas in the fracturing simulation process.

[0151] As an embodiment of this article, step 204, selecting the optimal fracturing scheme based on the active utilization coefficient of the stress field and the fracture network complexity coefficient, includes:

[0152] The stress field active utilization coefficient of each fracturing scheme is multiplied by the fracture network complexity coefficient.

[0153] Select the fracturing scheme with the largest calculation result.

[0154] Since both the active utilization coefficient of the stress field and the fracture network complexity coefficient can represent the effect of utilizing the spatial stress field in different fracturing schemes, the active utilization coefficient of the stress field W and the fracture network complexity coefficient θ can be calculated to balance different parameters and improve the recovery rate. Of course, in addition to multiplying the active utilization coefficient of the stress field W and the fracture network complexity coefficient θ, they can also be summed or calculated using the mean square error. Any calculation method that can unify the two can replace the embodiments in this paper, and this paper does not limit them.

[0155] After the stress field active utilization coefficient W and the fracture network complexity coefficient θ are calculated in a unified manner, the optimal fracturing scheme is selected from several fracturing schemes. The construction personnel then deploy the wells according to the optimal fracturing scheme and inject water into the horizontal injection wells according to the time sequence of the optimal fracturing scheme.

[0156] like Figure 8 The schematic diagram shown is of a three-dimensional well network dynamic stress field active utilization device. Based on the same inventive concept, embodiments of this specification also provide a three-dimensional well network dynamic stress field active utilization device, including:

[0157] Acquisition unit 801 is used to acquire several fracturing schemes for the target well network.

[0158] The structure determination unit 802 is configured to perform fracturing simulation on the target well pattern according to the fracturing scheme, and determine a fracturing structure of the target well pattern, where the fracturing structure represents a number and a morphology of fractures in the target well pattern.

[0159] The coefficient determination unit 803 is configured to determine a stress field active utilization coefficient and a fracture network complexity coefficient of the fracturing scheme according to the fracturing structure, where the stress field active utilization coefficient represents an active utilization effect of a stress field in the fracturing simulation process, and the fracture network complexity coefficient represents a proportion of a fracture area in the fracturing simulation process.

[0160] The scheme selection unit 804 is configured to select an optimal fracturing scheme according to the stress field active utilization coefficient and the fracture network complexity coefficient, so as to fracture the target well pattern.

[0161] The beneficial effects achieved by the above-described device are consistent with the beneficial effects achieved by the above-described method, and the embodiments of the present specification will not be described here.

[0162] As Figure 9 shown is a flowchart of a method for evaluating a three-dimensional well pattern space stress field active utilization method, and the steps of evaluating the active utilization effect of the dynamic stress field of the three-dimensional well pattern are described in the figure. It should be noted that the steps and order described in the figure are not the only steps and order for evaluating the active utilization effect of the dynamic stress field of the three-dimensional well pattern, and other steps and order for evaluating the active utilization effect of the dynamic stress field of the three-dimensional well pattern can also be obtained by those skilled in the art according to the content described in the figure, and the embodiments of the present specification are not limited.

[0163] In step 901, a Mohr circle envelope suitable for the target well pattern is obtained based on a large number of indoor experiments or experience data of adjacent blocks of the target well pattern.

[0164] In this step, the Mohr circle envelope of the geology where the target well pattern is located is determined through field exploration by construction personnel and laboratory experimental results, such as the Mohr circle envelope shown in Figure 6 , and the △ range of the Mohr circle envelope can be artificially preset, and the △ range is 5% in the embodiments of the present specification.

[0165] In step 902, a plurality of fracturing schemes of the target well pattern are designed, including different time sequences, different fracturing modes, and different well arrangement modes.

[0166] In this step, the target well pattern can be simulated and fractured through the fracturing schemes shown in Figure 3 and Figure 4 .

[0167] In step 903, the fracturing process of each fracturing scheme on the target well pattern is simulated.

[0168] In this step, the process of fracturing can be simulated by a multi-nonlinear platform to obtain the fracture morphology, fracture location and fracture number under the fracturing scheme.

[0169] Step 904, under each fracturing scheme, fracturing is performed according to the time sequence to determine whether the primary fracture will generate a secondary fracture. If yes, the secondary fracture is changed to the primary fracture, and the fracture morphology, fracture location and fracture number are obtained according to the time sequence T = ∞. Figure 6 Continue fracturing, and if no, stop fracturing and perform step 905.

[0170] In this step, in order to obtain all fractures under the fracturing scheme at the time sequence T = ∞ and evaluate the stress field active utilization effect of different fracturing schemes at T = ∞, all fractures need to be unable to continue fracturing.

[0171] Step 905, calculate the stress field active utilization coefficient and fracture network complexity coefficient of each fracturing scheme.

[0172] In this step, as described in the part of Figure 5 and Figure 7 , the quantitative value of the stress field active utilization effect of each fracturing scheme can be obtained.

[0173] Step 906, perform product operation on the stress field active utilization coefficient and the fracture network complexity coefficient, and select the optimal fracturing scheme.

[0174] In this step, in order to balance the stress field active utilization coefficient and the fracture network complexity coefficient, the two are operated, and of course, the product operation and the mean square difference operation can also be performed.

[0175] Step 907, the operator uses the optimal fracturing scheme to fracture the target well network.

[0176] In this step, the operator fractures the target well network according to the well location, fracture morphology, fracture location and fracture number of the fracturing scheme and the time sequence of water injection, which can achieve the effect of high single-well recovery.

[0177] As described in the part of Figure 10A structural diagram of a computer device of the embodiment is shown. The evaluation device of the active utilization effect of the three-dimensional well pattern dynamic stress field in the present embodiment can be the computer device in the embodiment, and the method in the present embodiment is executed. The computer device 1002 can include one or more processing devices 1004, such as one or more central processing units (CPUs), each of which can implement one or more hardware threads. The computer device 1002 can also include any storage resources 1006 for storing any kind of information such as code, settings, data, etc. Without limitation, for example, the storage resources 1006 can include any one or combination of the following: any type of RAM, any type of ROM, a flash memory device, a hard disk, an optical disk, etc. More generally, any storage resource can store information using any technology. Further, any storage resource can provide volatile or non-volatile retention of information. Further, any storage resource can represent a fixed or removable component of the computer device 1002. In one case, the computer device 1002 can perform any operation of the associated instructions when the processing device 1004 executes the associated instructions stored in any storage resource or combination of storage resources. The computer device 1002 also includes one or more drive mechanisms 1008 for interacting with any storage resource, such as a hard disk drive mechanism, an optical disk drive mechanism, etc.

[0178] The computer device 1002 can also include an input / output module 1010 (I / O) for receiving various inputs (via input devices 1012) and for providing various outputs (via output devices 1014). One particular output mechanism can include a presentation device 1016 and an associated graphical user interface (GUI) 1018. In other embodiments, the input / output module 1010 (I / O), the input devices 1012, and the output devices 1014 can also not be included, just as a computer device in a network. The computer device 1002 can also include one or more network interfaces 1020 for exchanging data with other devices via one or more communication links 1022. One or more communication buses 1024 couple the above-described components together.

[0179] The communication links 1022 can 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 links 1022 can include any combination of hardwired links, wireless links, routers, gateway functionality, name servers, etc., governed by any protocol or combination of protocols.

[0180] Corresponding to the method of Figures 2-7 The present embodiment also provides a computer readable storage medium, and the computer readable storage medium stores a computer program, and the computer program is executed by a processor to perform the above steps.

[0181] The embodiments herein also provide a computer program product comprising instructions which, when executed by a processor, cause the processor to carry out the method as Figures 2-7 shown.

[0182] It should be understood that the size of the serial number of the processes described above in the various embodiments herein does not mean the order of execution, and the execution order of the processes should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments herein.

[0183] It should also be understood that in the embodiments herein, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships. For example, A and / or B can represent the three cases of A existing alone, A and B existing together, and B existing alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are in an "or" relationship.

[0184] Those skilled in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized in electronic hardware, computer software or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of the examples have been described in the above description in general terms. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this paper.

[0185] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system, device and unit described above can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0186] In several embodiments provided herein, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the displays or discussed can be indirect coupling or communication connection through some interfaces, devices or units, and can also be electrical, mechanical or other forms of connection.

[0187] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, i.e. may be located in one place, or may be distributed on multiple network units. Part or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of the present application.

[0188] In addition, each functional unit in each embodiment herein can be integrated in one processing unit, or each unit can be physically present alone, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0189] The integrated unit, if realized in the form of a software functional unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on this understanding, the technical solutions herein, essentially or the part of the prior art that contributes to the technical solutions, or all or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for making a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in each embodiment herein. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0190] The principles and implementation manners of the present application are described in the specific embodiments herein, and the above embodiment descriptions are only used to help understand the methods and core ideas thereof; meanwhile, for those skilled in the art, according to the ideas herein, the specific implementation manners and application ranges will have changes, and the above description of the present application should not be understood as a limitation.

Claims

1. A method for actively utilizing the spatial stress field of a three-dimensional well network, characterized in that, include: Obtain several fracturing schemes for the target well network; Based on the fracturing scheme, the target well network is simulated to determine the fracturing structure of the target well network, wherein the fracturing structure characterizes the number and morphology of fractures in the target well network; Based on the fracturing structure, the stress field active utilization coefficient and the fracture network complexity coefficient of the fracturing scheme are determined, wherein the stress field active utilization coefficient characterizes the stress field active utilization effect in the fracturing simulation process, and the fracture network complexity coefficient characterizes the proportion of the fracture region in the fracturing simulation process. Based on the active utilization coefficient of the stress field and the fracture network complexity coefficient, the optimal fracturing scheme is selected to achieve fracturing of the target well network; The step of determining the active utilization coefficient of the stress field of the fracturing scheme based on the fracturing structure further includes: Based on extensive indoor experiments or empirical data from adjacent blocks in the target layer of the target well network, obtain the Mohr's circle envelope applicable to the target well network. Based on the fracturing structure, determine the spatial stress field at each point in the target well network; The regions where each point is located are divided according to the Mohr circle envelope and the spatial stress field of each point in the target well network. Each point in the target well network represents the regional attributes at the corresponding location. The types of divisions include fracture zone, network fracture potential zone, simple fracture potential zone and non-fracture potential zone. Weights are assigned to the crack zone, the mesh-like cracking potential zone, the simple cracking potential zone, and the non-crack potential zone; Based on the size and location of the area, the weight of each type of partition within the target well network, and the proportion of induced stress of each fracture in the target well network to each point in the target well network, the stress field active utilization coefficient of the target well network is determined. The step of determining the active utilization coefficient of the stress field of the target well network based on the size and location of the region, the weight of each type of partition within the target well network, and the proportion of induced stress of each fracture in the target well network on each point in the space, further includes: According to the formula Determine the active utilization coefficient of the stress field of the target well pattern; Wherein, W represents the active utilization coefficient of the stress field. In the target well network, target well network x1 to x n ,y1 to y n ,z1 to z n In the three-dimensional space, △x, △y, and △z represent the lengths of the regions in the three directions, n represents the number of x, y, and z regions of the target well network, and f j The weight of the partition is represented by k, the number of each type of partition is represented by g, the proportion of induced stress is represented by m, and the threshold value for descending ranking of the proportion of induced stress of cracks in the region is represented by m. The formula for calculating the proportion of induced stress is as follows: Where g represents the proportion of induced stress, s j (x,y,z) represents the spatial induced stress of the j-th fracture in the target well network on the x,y,z coordinates, and n represents the number of fractures in the target well network. Determining the fracture network complexity coefficient of the fracturing scheme further includes: Determine the fracture direction of each fracture within the target well network under the given fracturing scheme; The complexity coefficient of the crack network is determined based on the angle between the crack direction and the original geostress field direction, as well as the number of cracks in the space. The step of determining the fracture network complexity coefficient based on the angle between the fracture direction and the original geostress field direction, and the number of fractures in the space, further includes: The summation angles between the crack direction of each crack and the original geostress field direction are obtained. The fracture complexity coefficient of the target well network is determined by averaging the cumulative angles based on the number of fractures within the target well network.

2. The method for actively utilizing the spatial stress field of a three-dimensional well network according to claim 1, characterized in that, The step of determining the spatial stress field at each point in the target well network based on the fracturing structure further includes: The average pressure inside the crack is determined based on the size of the crack and the fluid pressure at the crack tip and root. The induced stress field of the crack is determined based on the size of the region, the size of the crack, and the average pressure within the crack. The induced stress field of all fractures in the target well network is superimposed with the original geostress field of the target well network to determine the spatial stress field at each point.

3. The method for actively utilizing the spatial stress field of a three-dimensional well network according to claim 1, characterized in that, The step of dividing the region where each point is located based on the Mohr's circle envelope and the spatial stress field of each point in the target well network further includes: Calculate the maximum horizontal principal stress, minimum horizontal principal stress, and vertical stress at each point in the target well network based on the spatial stress field. Calculate the area of ​​the coincident Mohr's circle at each point based on the maximum horizontal principal stress, the minimum horizontal principal stress, and the vertical stress. Within the coordinate system, determine the contact position between the overlapping area of ​​the Mohr's circles at each point in the space and the preset range of the envelope of the Mohr's circles; Based on the contact location, the points in the space are divided into partitions.

4. The method for actively utilizing the spatial stress field of a three-dimensional well network according to claim 1, characterized in that, The step of determining the fracture direction of each fracture within the target well network under the fracturing scheme further includes: Determining the type and direction of each fracture under the aforementioned fracturing scheme includes: When the crack is a tortuous crack, calculate the direction of the maximum horizontal principal stress at each point on the crack path, and take the average value of the direction of the maximum horizontal principal stress at each point as the crack direction. When the crack is a straight crack, calculate the direction of the maximum horizontal principal stress at the crack tip position and take the direction of the maximum horizontal principal stress at the crack tip position as the crack direction. Alternatively, determining the fracture direction by identifying the endpoint positions of each fracture under the fracturing scheme includes: Obtain the position of the crack tip and the crack initiation position, and determine the crack direction based on the direction of the crack tip position relative to the crack initiation position.

5. The method for actively utilizing the spatial stress field of a three-dimensional well network according to claim 1, characterized in that, The step of selecting the optimal fracturing scheme based on the active utilization coefficient of the stress field and the fracture network complexity coefficient further includes: The stress field active utilization coefficient of each fracturing scheme is multiplied by the fracture network complexity coefficient; Select the fracturing scheme with the largest calculation result.

6. A device for actively utilizing the spatial stress field of a three-dimensional well network, characterized in that, include: The acquisition unit is used to acquire several fracturing schemes for the target well network; The structure determination unit is used to perform fracturing simulation on the target well network according to the fracturing scheme and determine the fracturing structure of the target well network, wherein the fracturing structure characterizes the number and morphology of fractures in the target well network; The coefficient determination unit is used to determine the stress field active utilization coefficient and the fracture network complexity coefficient of the fracturing scheme according to the fracturing structure. The stress field active utilization coefficient characterizes the stress field active utilization effect in the fracturing simulation process, and the fracture network complexity coefficient characterizes the proportion of the fracture region in the fracturing simulation process. The scheme selection unit is used to select the optimal fracturing scheme based on the active utilization coefficient of the stress field and the fracture network complexity coefficient, so as to fracture the target well network; The coefficient determining unit is further configured to determine the active utilization coefficient of the stress field of the fracturing scheme based on the fracturing structure, further including: Based on extensive indoor experiments or empirical data from adjacent blocks in the target layer of the target well network, obtain the Mohr's circle envelope applicable to the target well network. Based on the fracturing structure, determine the spatial stress field at each point in the target well network; The regions where each point is located are divided according to the Mohr circle envelope and the spatial stress field of each point in the target well network. Each point in the target well network represents the regional attributes at the corresponding location. The types of divisions include fracture zone, network fracture potential zone, simple fracture potential zone and non-fracture potential zone. Weights are assigned to the crack zone, the mesh-like cracking potential zone, the simple cracking potential zone, and the non-crack potential zone; Based on the size and location of the area, the weight of each type of partition within the target well network, and the proportion of induced stress of each fracture in the target well network to each point in the target well network, the stress field active utilization coefficient of the target well network is determined. The step of determining the active utilization coefficient of the stress field of the target well network based on the size and location of the region, the weight of each type of partition within the target well network, and the proportion of induced stress of each fracture in the target well network on each point in the space, further includes: According to the formula Determine the active utilization coefficient of the stress field of the target well pattern; Wherein, W represents the active utilization coefficient of the stress field. In the target well network, target well network x1 to x n ,y1 to y n ,z1 to z n In the three-dimensional space, △x, △y, and △z represent the lengths of the regions in the three directions, n represents the number of x, y, and z regions of the target well network, and f j The weight of the partition is represented by k, the number of each type of partition is represented by g, the proportion of induced stress is represented by m, and the threshold value for descending ranking of the proportion of induced stress of cracks in the region is represented by m. The formula for calculating the proportion of induced stress is as follows: Where g represents the proportion of induced stress, s j (x,y,z) represents the spatial induced stress of the j-th fracture in the target well network on the x,y,z coordinates, and n represents the number of fractures in the target well network. Determining the fracture network complexity coefficient of the fracturing scheme further includes: Determine the fracture direction of each fracture within the target well network under the given fracturing scheme; The complexity coefficient of the crack network is determined based on the angle between the crack direction and the original geostress field direction, as well as the number of cracks in the space. The step of determining the fracture network complexity coefficient based on the angle between the fracture direction and the original geostress field direction, and the number of fractures in the space, further includes: The summation angles between the crack direction of each crack and the original geostress field direction are obtained. The fracture complexity coefficient of the target well network is determined by averaging the cumulative angles based on the number of fractures within the target well network.

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