Offshore inclined shaft fracturing cluster spacing determination method and system

Abstract

The invention relates to the technical field of petroleum engineering, and provides an offshore inclined shaft fracturing cluster interval determination method and system.The method comprises the steps that the slant distance between two main fractures is calculated, and the horizontal interval between fracture faces after the two main fractures are turned is calculated according to the slant distance; establishing a highly-deviated well cluster spacing optimization physical model; solving the highly-deviated well cluster spacing optimization physical model to obtain a crack three-dimensional induced stress numerical model; induced stress values in the horizontal minimum principal stress direction of the top of the first hydraulic fracture and the bottom of the second hydraulic fracture in the fracture three-dimensional induced stress numerical model are obtained; and determining the cluster spacing between the first hydraulic fracture and the second hydraulic fracture according to the overlapping condition of the first hydraulic fracture and the second hydraulic fracture and the induced stress value in the horizontal minimum principal stress direction. The invention provides a method for calculating the inclined shaft fracturing cluster spacing aiming at different fracture form directions of a near well and a far well of a highly-deviated well fracture so as to adapt to the fracturing transformation requirement of the highly-deviated well.

Description

Technical Field

[0001] The present invention relates to the field of petroleum engineering technology, and in particular to a method and system for determining the spacing between offshore deviated well fracturing clusters. Background Art

[0002] For offshore oil fields, the construction cost of drilling platforms is high, and the location is limited and fixed. Unlike onshore oil reservoirs, for wells far from the drilling platform, high-angle wells will be used for development, and the oil leakage area of ​​the reservoir will be maximized to increase the well production and the ultimate recovery rate of the reservoir. High-angle well technology is increasingly valued by domestic and foreign oil companies. High-angle wells can solve the problem of surface restrictions in offshore oil field development areas and are suitable for simultaneous multi-layer development. While increasing the detection range of gas-bearing areas, it can also increase the gas production of a single well. High-angle well multi-cluster hydraulic fracturing technology is an effective means to develop offshore oil and gas fields.

[0003] However, there are great differences between the fracturing of highly deviated wells and conventional vertical wells and horizontal fracturing, which is mainly reflected in the problems of fracture diversion and stress interference that occur during the fracturing process, resulting in complex fracture extension morphology, complex research mechanism, complex cluster spacing optimization principle, and difficult design. This is mainly reflected in the fact that the initial fracture orientation of the fracture in the deviated well fracturing will be perpendicular to the wellbore direction, but after moving away from the wellbore, it will be perpendicular to the horizontal minimum principal stress. Therefore, the impact caused by the "stress shadow" is relatively complex. The existing cluster spacing optimization models and methods are mainly aimed at horizontal wells. The models and methods used are only applicable to the case where the calculation of fractures is in the same horizontal plane. The hydraulic fracturing fractures of highly deviated wells are not in the same horizontal plane in space and are affected by fracture diversion. Therefore, the existing methods lack cluster spacing calculation methods that consider the different fracture morphology directions of the near well and far well of highly deviated well fractures, and it is difficult to adapt to the needs of highly deviated well fracturing transformation. Summary of the invention

[0004] The purpose of the present invention is to solve at least one technical problem in the background technology and to provide a method and system for determining the spacing between offshore deviated well fracturing clusters.

[0005] To achieve the above object, the present invention provides a method for determining the spacing of offshore deviated well fracturing clusters, comprising:

[0006] According to the geological sweet spots, the locations of cluster perforations in highly deviated wells are determined, where one main fracture is initiated at each cluster perforation location, and the slant distance between the two main fractures is calculated. Then, the horizontal distance between the fracture surfaces after the two main fractures turn is calculated based on the slant distance. Among them, the main fracture close to the bottom of the well is the first hydraulic fracture, and the main fracture close to the wellhead is the second hydraulic fracture.

[0007] Determine the half-fracture height and half-fracture length of the first hydraulic fracture and the second hydraulic fracture, and establish a physical model for optimizing the spacing of high-angle well clusters based on the fracture height, fracture length, horizontal spacing between fracture surfaces after diversion, rock property data, and boundary load data;

[0008] Solve the physical model for optimizing the spacing between clusters of highly deviated wells, select static solution, and obtain the three-dimensional numerical model of induced stress in fractures;

[0009] Obtain the induced stress value in the horizontal minimum principal stress direction at the top of the first hydraulic fracture and the bottom of the second hydraulic fracture in the three-dimensional induced stress numerical model of the fracture;

[0010] The cluster spacing between the first hydraulic fracture and the second hydraulic fracture is determined according to the overlap between the first hydraulic fracture and the second hydraulic fracture and the induced stress value in the horizontal minimum principal stress direction.

[0011] According to one aspect of the present invention, the step of calculating the horizontal distance between the crack surfaces after the two main cracks turn according to the slant distance comprises:

[0012] Calculate the horizontal spacing between two main cracks based on the slope distance;

[0013] The horizontal distance between the crack surfaces after the two main cracks turn is calculated based on the horizontal distance and the crack turning angle.

[0014] According to one aspect of the present invention, the calculation process of the crack turning angle includes:

[0015] The stress field distribution near the wellbore under the action of far-field stress and liquid pressure can be obtained by coordinate transformation:

[0016]

[0017] Where α is the azimuth angle of the wellbore axis relative to the x-axis; β is the inclination angle of the wellbore axis relative to the z-axis; σ H , σ h are the maximum and minimum horizontal principal stresses, respectively, and the ground stress σ v It is the vertical main ground force;

[0018] The stress state on the wellbore wall is:

[0019] σ z =σ zz -2μ(σ xx -σ yy )cos2θ-4μτ xy sin2θ

[0020] σ θ =(σ xx +σ yy )-2(σ xx -σ yy )cos2θ-4τ xy sin2θ-p w ;

[0021] τθz =2(-τ xz sinθ+τ yz cosθ)

[0022] Where σ xx , σ yy , σ zz , τ xy , τ yz , τ xz are the stress components on the wellbore wall in rectangular coordinates; σ z , σ θ , τ θz are the stress components on the wellbore wall in the wellbore cylindrical coordinates; μ is the Poisson's ratio; θ is the angle between the line connecting any point on the wellbore wall and the wellbore center point in the wellbore cylindrical coordinates and the y-axis of the wellbore cylindrical coordinates; p w is the wellbore internal pressure;

[0023] The crack turning angle γ is:

[0024]

[0025] According to one aspect of the present invention, the rock property data include rock elastic modulus and rock density; the boundary load data is the net pressure in the hydraulic fracture, and the net pressure in the hydraulic fracture is used as a boundary load, which is applied to the surfaces of the first hydraulic fracture and the second hydraulic fracture, and the directions are respectively perpendicular to the surface of the first hydraulic fracture facing the second hydraulic fracture and the surface of the second hydraulic fracture facing the first hydraulic fracture.

[0026] According to one aspect of the present invention, the cluster spacing between the first hydraulic fracture and the second hydraulic fracture is determined according to the overlap between the first hydraulic fracture and the second hydraulic fracture and the induced stress value in the horizontal minimum principal stress direction as follows:

[0027] When the projections of the first hydraulic fracture and the second hydraulic fracture overlap, the induced stress generated by the first hydraulic fracture and the second hydraulic fracture in the direction of the horizontal minimum principal stress must be at least less than or equal to zero;

[0028] The cluster spacing when the induced stress in the horizontal minimum principal stress direction at the overlap of the first hydraulic fracture and the second hydraulic fracture is 0 is selected as the recommended cluster spacing.

[0029] To achieve the above object, the present invention also provides a method for determining the spacing of offshore deviated well fracturing clusters, comprising:

[0030] The module for calculating the horizontal spacing is turned to determine the location of cluster perforations in highly deviated wells according to the geological sweet spots. A main fracture is initiated at the location of each cluster perforation. The slant distance between the two main fractures is calculated. Then, the horizontal spacing between the fracture surfaces after the two main fractures are turned is calculated based on the slant distance. The main fracture close to the bottom of the well is the first hydraulic fracture, and the main fracture close to the wellhead is the second hydraulic fracture.

[0031] The physical model construction module for optimizing the spacing between highly deviated well clusters determines the half-fracture height and half-fracture length of the first hydraulic fracture and the second hydraulic fracture, and establishes a physical model for optimizing the spacing between highly deviated well clusters based on the fracture height, fracture length, horizontal spacing between fracture surfaces after diversion, rock property data, and boundary load data.

[0032] The module for acquiring the numerical model of fracture induced stress in three dimensions solves the physical model for optimizing the spacing between clusters of highly deviated wells, selects static solution, and obtains the numerical model of fracture induced stress in three dimensions.

[0033] An induced stress value acquisition module is used to acquire the induced stress value in the horizontal minimum principal stress direction at the top of the first hydraulic fracture and the bottom of the second hydraulic fracture in the three-dimensional induced stress numerical model of the fracture;

[0034] The cluster spacing determination module determines the cluster spacing between the first hydraulic fracture and the second hydraulic fracture according to the overlap between the first hydraulic fracture and the second hydraulic fracture and the induced stress value in the horizontal minimum principal stress direction.

[0035] To achieve the above objectives, the present invention also provides an electronic device, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the above-mentioned method for determining the spacing of offshore inclined well fracturing clusters.

[0036] To achieve the above object, the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the method for determining the spacing between offshore deviated well fracturing clusters as described above is implemented.

[0037] According to the solution of the present invention, in the current fracturing design and field operations of highly deviated wells, the present invention proposes a calculation method for the spacing between deviated well fracturing clusters based on the different fracture morphology directions of the near-well and far-well fractures in highly deviated wells to meet the needs of fracturing transformation of highly deviated wells.

[0038] According to the solution of the present invention, the present invention considers the influence of crack turning in highly deviated wells on crack expansion, designs a reasonable cluster spacing, optimizes the design of crack parameters, achieves the expected crack combination form, and thus meets the technical requirements of highly deviated well fracture network fracturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1A flow chart schematically showing a method for determining the spacing between offshore deviated well fracturing clusters according to an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of a high-angle well fracturing structure according to an embodiment of the present invention is shown;

[0041] Figure 3 A schematic diagram of a high-angle well fracturing structure according to an embodiment of the present invention is shown;

[0042] Figure 4 A schematic diagram showing a stress field distribution diagram near a wellbore of a highly deviated well according to an embodiment of the present invention;

[0043] Figure 5 A diagram schematically showing a physical model diagram for optimizing the spacing between clusters of highly deviated wells according to an embodiment of the present invention;

[0044] Figure 6 A diagram schematically shows a three-dimensional fracture induced stress numerical model according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The present invention will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only to enable those skilled in the art to better understand and thus implement the present invention, rather than implying any limitation on the scope of the present invention.

[0046] As used herein, the term “including” and variations thereof are to be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” is to be interpreted as “based, at least in part, on.” The terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment.”

[0047] Figure 1 The flowchart schematically shows a method for determining the spacing between offshore deviated well fracturing clusters according to an embodiment of the present invention. Figure 1 As shown, in this embodiment, the method for determining the spacing between offshore deviated well fracturing clusters includes:

[0048] According to the geological sweet spots, the locations of cluster perforations in highly deviated wells are determined, where one main fracture is initiated at each cluster perforation location, and the slant distance between the two main fractures is calculated. Then, the horizontal distance between the fracture surfaces after the two main fractures turn is calculated based on the slant distance. Among them, the main fracture close to the bottom of the well is the first hydraulic fracture, and the main fracture close to the wellhead is the second hydraulic fracture.

[0049] Determine the half-fracture height and half-fracture length of the first hydraulic fracture and the second hydraulic fracture, and establish a physical model for optimizing the spacing of high-angle well clusters based on the fracture height, fracture length, horizontal spacing between fracture surfaces after diversion, rock property data, and boundary load data;

[0050] Solve the physical model for optimizing the spacing between clusters of highly deviated wells, select static solution, and obtain the three-dimensional numerical model of induced stress in fractures;

[0051] Obtain the induced stress value in the horizontal minimum principal stress direction at the top of the first hydraulic fracture and the bottom of the second hydraulic fracture in the three-dimensional induced stress numerical model of the fracture;

[0052] The cluster spacing between the first hydraulic fracture and the second hydraulic fracture is determined according to the overlap (projection overlap) between the first hydraulic fracture and the second hydraulic fracture and the induced stress value in the horizontal minimum principal stress direction.

[0053] Further, Figure 2 A schematic diagram of a high-angle well fracturing structure according to an embodiment of the present invention is shown; Figure 3 A schematic diagram of a high-angle well fracturing structure according to an embodiment of the present invention is shown. Figure 2 and Figure 3 As shown, in this embodiment, the slant distance between two main fractures in the highly deviated well 3 is calculated, and the horizontal distance between the fracture surfaces after the two main fractures are turned is calculated according to the slant distance, including:

[0054] The horizontal distance D (the horizontal distance between the fracture surfaces before turning) between the two main fractures (the first hydraulic fracture 1 and the second hydraulic fracture 2) is calculated based on the slant distance d;

[0055] The horizontal spacing L between the crack surfaces after the two main cracks are turned is calculated based on the horizontal spacing and the crack turning angle.

[0056] Further, according to one embodiment of the present invention, Figure 4 As shown in Figure 2, the calculation process of the crack turning angle includes:

[0057] The stress field distribution near the wellbore 4 under the action of far-field stress and liquid pressure can be obtained by coordinate transformation:

[0058]

[0059] Where α is the azimuth angle of the wellbore axis relative to the x-axis; β is the inclination angle of the wellbore axis relative to the z-axis; σ H , σ h are the maximum and minimum horizontal principal stresses, respectively, and the ground stress σ v It is the vertical main ground force;

[0060] The stress state on the wellbore wall is:

[0061] σ z =σ zz -2μ(σ xx -σ yy )cos2θ-4μτxy sin2θ

[0062] σ θ =(σ xx +σ yy )-2(σ xx -σ yy )cos2θ-4τ xy sin2θ-p w ;

[0063] τ θz =2(-τ xz sinθ+τ yz cosθ)

[0064] Where σ xx , σ yy , σ zz , τ xy , τ yz , τ xz are the stress components on the wellbore wall in rectangular coordinates; σ z , σ θ , τ θz are the stress components on the wellbore wall in the wellbore cylindrical coordinates; μ is the Poisson's ratio; θ is the stress component of any point on the wellbore wall in the wellbore cylindrical coordinates (such as Figure 4 The angle between the line connecting point A in the middle and the center point of the well wall and the y-axis of the wellbore column coordinate; w is the wellbore internal pressure;

[0065] The crack turning angle γ is:

[0066]

[0067] Further, according to an embodiment of the present invention, the half fracture height and half fracture length of the first hydraulic fracture and the second hydraulic fracture are determined, and based on the fracture height, fracture length and horizontal spacing between fracture surfaces after diversion, rock property data and boundary load data, a physical model for optimizing the spacing of high-angle well clusters is established as follows:

[0068] According to the fracture diagnosis results obtained in the offshore block based on microseismic, net pressure fitting and RTA analysis, the half-fracture height and half-fracture length of the first hydraulic fracture 1 and the second hydraulic fracture 2 are determined. Based on the fracture height, fracture length and horizontal spacing of the fractures after diversion, rock property data and boundary load data, a physical model for optimizing the spacing of high-angle well clusters is established in COMSOL Multiphysics software, such as Figure 5As shown in the figure, the fracture morphology in the model is represented by half of an ellipse, the center of the ellipse is the middle of the fracture, the area outside the fracture is rock, and except for the surface where the boundary load data is applied, the other surfaces are normal immovable boundaries. The length direction of the model is the half-fracture length direction after the turn, and its size is greater than the half-fracture length of the first hydraulic fracture 1 and the second hydraulic fracture 2. The width of the model is equal to the horizontal spacing of the fractures after the turn, and the height of the model is equal to the height of the fractures after the turn, as shown in the figure. Figure 3 As shown in Figure 2, the fracture height dimension can also be calculated based on the horizontal spacing between fracture surfaces after diversion and the well inclination angle.

[0069] Furthermore, in this embodiment, rock property data are determined based on data from previous tests, well logging, on-site construction, etc. of the block, specifically including rock elastic modulus and rock density; boundary load data are the net pressure in the hydraulic fracture, and the net pressure in the hydraulic fracture is used as a boundary load, which is applied to the surfaces of the first hydraulic fracture 1 and the second hydraulic fracture 2, in directions perpendicular to the surface of the first hydraulic fracture 1 facing the second hydraulic fracture 2 and the surface of the second hydraulic fracture 2 facing the first hydraulic fracture 1, respectively.

[0070] Further, according to an embodiment of the present invention, the physical model for optimizing the spacing between clusters of highly deviated wells is solved by using a built-in solver in the software, and a static solution is selected, such as Figure 5 As shown, the mesh parameters are default parameters, and the three-dimensional numerical model of crack induced stress is obtained.

[0071] In this embodiment, if Figure 6 As shown, the induced stress values ​​in the horizontal minimum principal stress direction at the top of the first hydraulic fracture and the bottom of the second hydraulic fracture in the three-dimensional induced stress numerical model of the fracture are obtained. Among them, the direction perpendicular to the fracture wall is the minimum horizontal principal stress direction.

[0072] Further, according to an embodiment of the present invention, the cluster spacing between the first hydraulic fracture and the second hydraulic fracture is determined according to the overlap between the first hydraulic fracture and the second hydraulic fracture and the induced stress value in the horizontal minimum principal stress direction:

[0073] When the projections of the first hydraulic fracture and the second hydraulic fracture overlap, the induced stress generated by the first hydraulic fracture and the second hydraulic fracture in the direction of the horizontal minimum principal stress must be at least less than or equal to zero;

[0074] The cluster spacing when the induced stress in the horizontal minimum principal stress direction at the overlap of the first hydraulic fracture and the second hydraulic fracture is 0 is selected as the recommended cluster spacing.

[0075] In this embodiment, it is assumed that the first hydraulic fracture 1 and the second hydraulic fracture 2 have the same size. Therefore, when the cluster spacing is too small, that is, the first hydraulic fracture 1 and the second hydraulic fracture 2 have overlapping fracture heights, the induced stress fields generated by the two fractures overlap. Therefore, when the cluster spacing is too large, that is, the first hydraulic fracture 1 and the second hydraulic fracture 2 have no overlapping fracture heights, the induced stress fields generated by the two fractures do not overlap.

[0076] Cluster spacing analysis and calculation: When the induced stress is positive, it is compressive stress; when it is negative, it is tensile stress. When the projections of the two fracture surfaces overlap, the induced stress field of the sharp compressive stress generated by the first hydraulic fracture 1 and the second hydraulic fracture 2 in the horizontal minimum principal stress direction should be avoided, so that the first hydraulic fracture 1 and the second hydraulic fracture 2 squeeze each other, so that the length and width of the fractures are limited. Then, the induced stress generated by the first hydraulic fracture 1 and the second hydraulic fracture 2 in the horizontal minimum principal stress direction must be at least less than or equal to zero. Therefore, the cluster spacing when the induced stress in the horizontal minimum principal stress direction of the fracture overlap is 0 is selected as the recommended cluster spacing.

[0077] According to the above scheme of the present invention, in the current fracturing design and field operations of highly deviated wells, the present invention proposes a calculation method for the spacing between deviated well fracturing clusters according to the different fracture morphology directions of the near-well and far-well fractures in highly deviated wells to meet the needs of fracturing transformation of highly deviated wells.

[0078] According to the above scheme of the present invention, the present invention considers the influence of crack turning in highly deviated wells on crack expansion, designs a reasonable cluster spacing, optimizes the design of crack parameters, achieves the expected crack combination form, and thus meets the technical requirements of highly deviated well fracture network fracturing.

[0079] Furthermore, to achieve the above-mentioned purpose, the present invention also provides a system for determining the spacing between offshore inclined well fracturing clusters, comprising:

[0080] The module for calculating the horizontal spacing is turned to determine the location of cluster perforations in highly deviated wells according to the geological sweet spots. A main fracture is initiated at the location of each cluster perforation. The slant distance between the two main fractures is calculated. Then, the horizontal spacing between the fracture surfaces after the two main fractures are turned is calculated based on the slant distance. The main fracture close to the bottom of the well is the first hydraulic fracture, and the main fracture close to the wellhead is the second hydraulic fracture.

[0081] The physical model construction module for optimizing the spacing between highly deviated well clusters determines the half-fracture height and half-fracture length of the first hydraulic fracture and the second hydraulic fracture, and establishes a physical model for optimizing the spacing between highly deviated well clusters based on the fracture height, fracture length, horizontal spacing between fracture surfaces after diversion, rock property data, and boundary load data.

[0082] The module for acquiring the numerical model of fracture induced stress in three dimensions solves the physical model for optimizing the spacing between clusters of highly deviated wells, selects static solution, and obtains the numerical model of fracture induced stress in three dimensions.

[0083] An induced stress value acquisition module is used to acquire the induced stress value in the horizontal minimum principal stress direction at the top of the first hydraulic fracture and the bottom of the second hydraulic fracture in the three-dimensional induced stress numerical model of the fracture;

[0084] The cluster spacing determination module determines the cluster spacing between the first hydraulic fracture and the second hydraulic fracture according to the overlap between the first hydraulic fracture and the second hydraulic fracture and the induced stress value in the horizontal minimum principal stress direction.

[0085] Furthermore, if Figure 2 and Figure 3 As shown, in this embodiment, the horizontal distance between the crack surfaces after the two main cracks turn is calculated according to the slant distance, including:

[0086] Calculate the horizontal distance between two main fractures (the first hydraulic fracture 1 and the second hydraulic fracture 2) according to the slant distance;

[0087] The horizontal distance between the crack surfaces after the two main cracks turn is calculated based on the horizontal distance and the crack turning angle.

[0088] Further, according to one embodiment of the present invention, Figure 4 As shown in Figure 2, the calculation process of the crack turning angle includes:

[0089] The stress field distribution near the wellbore under the action of far-field stress and liquid pressure can be obtained by coordinate transformation:

[0090]

[0091] Where α is the azimuth angle of the wellbore axis relative to the x-axis; β is the inclination angle of the wellbore axis relative to the z-axis; σ H , σ h are the maximum and minimum horizontal principal stresses, respectively, and the ground stress σ v It is the vertical main ground force;

[0092] The stress state on the wellbore wall is:

[0093] σ z =σ zz -2μ(σ xx -σ yy )cos2θ-4μτ xy sin2θ

[0094] σ θ =(σ xx +σ yy )-2(σ xx -σ yy )cos2θ-4τ xy sin2θ-p w ;

[0095] τ θz =2(-τ xz sinθ+τ yz cosθ)

[0096] Where σ xx , σ yy , σ zz , τ xy , τ yz , τ xz are the stress components on the wellbore wall in rectangular coordinates; σ z , σ θ , τ θz are the stress components on the wellbore wall in the wellbore cylindrical coordinates; μ is the Poisson's ratio; θ is the angle between the line connecting any point on the wellbore wall and the wellbore center point in the wellbore cylindrical coordinates and the y-axis of the wellbore cylindrical coordinates; p w is the wellbore internal pressure;

[0097] The crack turning angle γ is:

[0098]

[0099] Further, according to an embodiment of the present invention, the half fracture height and half fracture length of the first hydraulic fracture and the second hydraulic fracture are determined, and based on the fracture height, fracture length and horizontal spacing between fracture surfaces after diversion, rock property data and boundary load data, a physical model for optimizing the spacing of high-angle well clusters is established as follows:

[0100] According to the fracture diagnosis results obtained in the offshore block based on microseismic, net pressure fitting and RTA analysis, the half-fracture height and half-fracture length of the first hydraulic fracture 1 and the second hydraulic fracture 2 are determined. Based on the fracture height, fracture length and horizontal spacing of the fractures after diversion, rock property data and boundary load data, a physical model for optimizing the spacing of high-angle well clusters is established in COMSOL Multiphysics software, such as Figure 5 As shown in the figure, the fracture morphology in the model is represented by half of an ellipse, the center of the ellipse is the middle of the fracture, the area outside the fracture is rock, and except for the surface where the boundary load data is applied, the other surfaces are normal immovable boundaries. The length direction of the model is the half-fracture length direction after the turn, and its size is greater than the half-fracture length of the first hydraulic fracture 1 and the second hydraulic fracture 2. The width of the model is equal to the horizontal spacing of the fractures after the turn, and the height of the model is equal to the height of the fractures after the turn, as shown in the figure. Figure 3 As shown in Figure 2, the fracture height dimension can also be calculated based on the horizontal spacing between fracture surfaces after diversion and the well inclination angle.

[0101] Furthermore, in this embodiment, rock property data are determined based on data from previous tests, well logging, on-site construction, etc. of the block, specifically including rock elastic modulus and rock density; boundary load data are the net pressure in the hydraulic fracture, and the net pressure in the hydraulic fracture is used as a boundary load, which is applied to the surfaces of the first hydraulic fracture 1 and the second hydraulic fracture 2, in directions perpendicular to the surface of the first hydraulic fracture 1 facing the second hydraulic fracture 2 and the surface of the second hydraulic fracture 2 facing the first hydraulic fracture 1, respectively.

[0102] Further, according to an embodiment of the present invention, the physical model for optimizing the spacing between clusters of highly deviated wells is solved by using a built-in solver in the software, and a static solution is selected, such as Figure 5 As shown, the mesh parameters are default parameters, and the three-dimensional numerical model of crack induced stress is obtained.

[0103] In this embodiment, if Figure 6 As shown, the induced stress values ​​in the horizontal minimum principal stress direction at the top of the first hydraulic fracture and the bottom of the second hydraulic fracture in the three-dimensional induced stress numerical model of the fracture are obtained. Among them, the direction perpendicular to the fracture wall is the minimum horizontal principal stress direction.

[0104] Further, according to an embodiment of the present invention, the cluster spacing between the first hydraulic fracture and the second hydraulic fracture is determined according to the overlap between the first hydraulic fracture and the second hydraulic fracture and the induced stress value in the horizontal minimum principal stress direction:

[0105] When the projections of the first hydraulic fracture and the second hydraulic fracture overlap, the induced stress generated by the first hydraulic fracture and the second hydraulic fracture in the direction of the horizontal minimum principal stress must be at least less than or equal to zero;

[0106] The cluster spacing when the induced stress in the horizontal minimum principal stress direction at the overlap of the first hydraulic fracture and the second hydraulic fracture is 0 is selected as the recommended cluster spacing.

[0107] In this embodiment, it is assumed that the first hydraulic fracture 1 and the second hydraulic fracture 2 have the same size. Therefore, when the cluster spacing is too small, that is, the first hydraulic fracture 1 and the second hydraulic fracture 2 have overlapping fracture heights, the induced stress fields generated by the two fractures overlap. Therefore, when the cluster spacing is too large, that is, the first hydraulic fracture 1 and the second hydraulic fracture 2 have no overlapping fracture heights, the induced stress fields generated by the two fractures do not overlap.

[0108] Cluster spacing analysis and calculation: When the induced stress is positive, it is compressive stress; when it is negative, it is tensile stress. When the projections of the two fracture surfaces overlap, the induced stress field of the sharp compressive stress generated by the first hydraulic fracture 1 and the second hydraulic fracture 2 in the horizontal minimum principal stress direction should be avoided, so that the first hydraulic fracture 1 and the second hydraulic fracture 2 squeeze each other, so that the length and width of the fractures are limited. Then, the induced stress generated by the first hydraulic fracture 1 and the second hydraulic fracture 2 in the horizontal minimum principal stress direction must be at least less than or equal to zero. Therefore, the cluster spacing when the induced stress in the horizontal minimum principal stress direction of the fracture overlap is 0 is selected as the recommended cluster spacing.

[0109] According to the above scheme of the present invention, in the current fracturing design and field operations of highly deviated wells, the present invention proposes a calculation method for the spacing between deviated well fracturing clusters according to the different fracture morphology directions of the near-well and far-well fractures in highly deviated wells to meet the needs of fracturing transformation of highly deviated wells.

[0110] According to the above scheme of the present invention, the present invention considers the influence of crack turning in highly deviated wells on crack expansion, designs a reasonable cluster spacing, optimizes the design of crack parameters, achieves the expected crack combination form, and thus meets the technical requirements of highly deviated well fracture network fracturing.

[0111] Furthermore, to achieve the above objectives, the present invention also provides an electronic device, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the method for determining the spacing between offshore deviated well fracturing clusters as described above is implemented.

[0112] Furthermore, to achieve the above-mentioned purpose, the present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the above-mentioned offshore deviated well fracturing cluster spacing determination method is implemented.

[0113] Based on the above-mentioned solution of the present invention, the technical solution of the present invention is described in detail in the form of a specific embodiment as follows.

[0114] Taking an offshore oil field as an example, according to the given geological sweet spot, the location of cluster perforation is determined. The slant distance between the two perforation locations is 50m, the well inclination is 53.13°, the azimuth is 20°, the overburden stress is 75MPa, the maximum horizontal principal stress is 67MPa, and the minimum horizontal principal stress is 62MPa. The horizontal spacing between the fracture surfaces before turning is 40m, the fracture turning angle is 20°, and the horizontal spacing between the fracture surfaces after turning is 14m, and the vertical spacing is 30m. According to the reservoir fracture monitoring and inversion results, the half-fracture length is 80m and the half-fracture height is 15m. The net pressure in the fracture is 10MPa. The elastic modulus is 36GPa, the Poisson's ratio is 0.2, and the rock density is 2603Kg / m 3 .

[0115] Based on COMSOL Multiphysics software and the above parameters, a physical model for optimizing the spacing between high-angle well clusters with a model size of 80×200×40m was established.

[0116] The pressure perpendicular to the fracture surface after the diversion is set to act on the first hydraulic fracture 1 and the second hydraulic fracture 2, and its value is 10 MPa. The model is solved using a steady-state solver and a refined grid to obtain a three-dimensional induced stress numerical model of the fracture, and the induced stress value in the direction of the minimum horizontal principal stress at the model analysis position is obtained.

[0117] According to the solution results, the induced stress curve of the minimum horizontal principal stress direction at the center of two cracks is given when the cracks overlap.

[0118] According to the changes in the induced stress field in the induced stress curve, when the distance between the first hydraulic fracture 1 and the second hydraulic fracture 2 after the diversion is less than 14m, tensile stress is generated between the first hydraulic fracture 1 and the second hydraulic fracture 2, which will lead to limited expansion of the length and width of the fracture. At the same time, in order to avoid insufficient transformation, it is recommended that the distance between the two fractures before diversion should be 50m.

[0119] Those skilled in the art will appreciate that the modules and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0120] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and equipment can refer to the corresponding processes in the aforementioned method implementation methods, and will not be repeated here.

[0121] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0122] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the embodiments of the present invention.

[0123] In addition, each functional module in the embodiment of the present invention may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0124] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the energy-saving signal sending / receiving method of each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical disks.

[0125] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other.

[0126] It should be understood that the size of the serial numbers of each step in the content of the invention and the implementation methods of the present invention does not absolutely mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation methods of the present invention.

Claims

1. A method for determining the spacing between offshore inclined well fracturing clusters, characterized in that: include: According to the geological sweet spots, the locations of cluster perforations in highly deviated wells are determined, where one main fracture is initiated at each cluster perforation location, and the slant distance between the two main fractures is calculated. Then, the horizontal distance between the fracture surfaces after the two main fractures turn is calculated based on the slant distance. Among them, the main fracture close to the bottom of the well is the first hydraulic fracture, and the main fracture close to the wellhead is the second hydraulic fracture. Determine the half-fracture height and half-fracture length of the first hydraulic fracture and the second hydraulic fracture, and establish a physical model for optimizing the spacing of high-angle well clusters based on the fracture height, fracture length, horizontal spacing between fracture surfaces after diversion, rock property data, and boundary load data; Solve the physical model for optimizing the spacing between clusters of highly deviated wells, select static solution, and obtain the three-dimensional numerical model of induced stress in fractures; Obtaining the induced stress values ​​in the horizontal minimum principal stress direction at the top of the first hydraulic fracture and the bottom of the second hydraulic fracture in the three-dimensional induced stress numerical model of the fracture; The cluster spacing between the first hydraulic fracture and the second hydraulic fracture is determined according to the overlap between the first hydraulic fracture and the second hydraulic fracture and the induced stress value in the horizontal minimum principal stress direction.

2. The offshore inclined well fracturing cluster spacing determination method according to claim 1, characterized in that: The method of calculating the horizontal distance between the crack surfaces after the two main cracks turn according to the slope distance includes: Calculate the horizontal spacing between two main cracks based on the slope distance; The horizontal distance between the crack surfaces after the two main cracks turn is calculated based on the horizontal distance and the crack turning angle.

3. The offshore deviated well fracturing cluster spacing determination method according to claim 2, characterized in that: The calculation process of the crack turning angle includes: The stress field distribution near the wellbore under the action of far-field stress and liquid pressure can be obtained by coordinate transformation: Where α is the azimuth angle of the wellbore axis relative to the x-axis; β is the inclination angle of the wellbore axis relative to the z-axis; σ H , σ h are the maximum and minimum horizontal principal stresses, respectively, and the ground stress σ v It is the vertical main ground force; The stress state on the wellbore wall is: Where σ xx , σ yy , σ zz , τ xy , τ yz , τ xz are the stress components on the wellbore wall in rectangular coordinates; σ z , σ θ , τ θz are the stress components on the wellbore wall in the wellbore cylindrical coordinates; μ is the Poisson's ratio; θ is the angle between the line connecting any point on the wellbore wall and the wellbore center point in the wellbore cylindrical coordinates and the y-axis of the wellbore cylindrical coordinates; p w is the wellbore internal pressure; The crack turning angle γ is:

4. The offshore deviated well fracturing cluster spacing determination method according to claim 1, characterized in that: The rock property data include rock elastic modulus and rock density; the boundary load data is the net pressure in the hydraulic fracture. The net pressure in the hydraulic fracture is used as the boundary load and is applied to the surfaces of the first hydraulic fracture and the second hydraulic fracture in a direction perpendicular to the surface of the first hydraulic fracture facing the second hydraulic fracture and the surface of the second hydraulic fracture facing the first hydraulic fracture.

5. The method for determining the spacing between offshore deviated well fracturing clusters according to any one of claims 1 to 4, characterized in that: The cluster spacing between the first hydraulic fracture and the second hydraulic fracture is determined according to the overlap between the first hydraulic fracture and the second hydraulic fracture and the induced stress value in the horizontal minimum principal stress direction as follows: When the projections of the first hydraulic fracture and the second hydraulic fracture overlap, the induced stress generated by the first hydraulic fracture and the second hydraulic fracture in the direction of the horizontal minimum principal stress must be at least less than or equal to zero; The cluster spacing when the induced stress in the horizontal minimum principal stress direction at the overlap of the first hydraulic fracture and the second hydraulic fracture is 0 is selected as the recommended cluster spacing.

6. Offshore inclined well fracturing cluster spacing determination system, characterized in that: include: The module for calculating the horizontal spacing is turned to determine the location of cluster perforations in highly deviated wells according to the geological sweet spots. A main fracture is initiated at the location of each cluster perforation. The slant distance between the two main fractures is calculated. Then, the horizontal spacing between the fracture surfaces after the two main fractures are turned is calculated based on the slant distance. The main fracture close to the bottom of the well is the first hydraulic fracture, and the main fracture close to the wellhead is the second hydraulic fracture. The physical model construction module for optimizing the spacing between highly deviated well clusters determines the half-fracture height and half-fracture length of the first hydraulic fracture and the second hydraulic fracture, and establishes a physical model for optimizing the spacing between highly deviated well clusters based on the fracture height, fracture length, horizontal spacing between fracture surfaces after diversion, rock property data, and boundary load data. The module for acquiring the numerical model of fracture induced stress in three dimensions solves the physical model for optimizing the spacing between clusters of highly deviated wells, selects static solution, and obtains the numerical model of fracture induced stress in three dimensions. An induced stress value acquisition module is used to acquire the induced stress value in the horizontal minimum principal stress direction at the top of the first hydraulic fracture and the bottom of the second hydraulic fracture in the three-dimensional induced stress numerical model of the fracture; The cluster spacing determination module determines the cluster spacing between the first hydraulic fracture and the second hydraulic fracture according to the overlap between the first hydraulic fracture and the second hydraulic fracture and the induced stress value in the horizontal minimum principal stress direction.

7. An electronic device, characterized in that The invention comprises a processor, a memory and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the method for determining the spacing between offshore deviated well fracturing clusters as claimed in any one of claims 1 to 5 is implemented.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for determining the spacing between offshore deviated well fracturing clusters according to any one of claims 1 to 5 is implemented.

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