Display method of natural crack in platform fracturing design

Abstract

The invention provides a display method for natural fractures in platform fracturing design. The method comprises the steps that a horizontal section starting point, namely, an A target point, and a horizontal section ending point, namely, a B target point, of a well body track of a design well are obtained; constructing a fractured well platform coordinate system, translating and transforming the coordinates of the target point A to the origin of the coordinate axis of the fractured well platform coordinate system to obtain a translation transformation model, and translating and transforming the coordinates of the target point B according to the translation transformation model; rotating the B target spot after translation transformation to the Y axis of the coordinate system coordinate of the fracturing well platform to obtain a rotation transformation model; horizontal projection coordinates of the well body track and key point coordinates of the large-scale natural fracture are obtained, and the large-scale natural fracture and the well body track are displayed in a fractured well platform design coordinate system after transformation of the translation transformation model and the rotation transformation model; according to the method, the natural fracture is visually displayed in the platform fracturing design, the comparison between the platform fracturing design fracture propagation model and the natural fracture position is realized, and the safety and accuracy of the platform fracturing simulation scheme are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas development, and more specifically, to a method for displaying natural fractures in platform fracturing design, which converts the coordinates of the natural fracture data volume in seismic data into the corresponding coordinates for platform fracturing design. Background Art

[0002] At present, the shale oil and gas reservoirs adopt the platform well pattern fracturing development mode to form a complex three-dimensional fracture network and fully exploit the reservoir oil and gas. For shale oil and gas fracturing, it is necessary to avoid a large amount of fracturing fluid communicating with the natural fracture dense area, which may cause shear slip of natural fractures, resulting in casing deformation or disconnection, and reducing the production effect.

[0003] For shale oil and gas fracturing development, a platform overall fracturing plan is designed to establish a three-dimensional fracture propagation model for the platform well pattern. At present, the coordinates of the natural fracture data volume in seismic data cannot be converted into the relative coordinates for platform fracturing design. The fracture propagation model in platform fracturing design cannot be compared with the position of natural fractures to confirm whether the fractures in the fracturing simulation plan communicate with the natural fracture dense area and judge the risk of the fracturing plan.

[0004] Currently, if natural fractures are considered in fracturing design, it is necessary to use Petrel software to establish a three-dimensional geological and fracture model. Based on the geological model and fracture model, Kinetix software is used to simulate the fracturing plan. This requires a large amount of seismic and geological data, with a complex process, high operation difficulty, and low efficiency. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a method for displaying natural fractures in platform fracturing design, establishes a fracturing well platform coordinate system, converts the coordinates of the natural fracture data volume in seismic data into the corresponding coordinates for fracturing design, intuitively displays the natural fractures in platform fracturing design, realizes the comparison between the fracture propagation model in platform fracturing design and the position of natural fractures, and improves the safety and accuracy of the platform fracturing simulation plan.

[0006] To achieve the above object, the present invention provides the following technical solution: A method for displaying natural fractures in platform fracturing design, the specific steps are as follows:

[0007] S1 Obtain the coordinates of the key points of the designed wellbore trajectory. The key points of the wellbore trajectory include the starting point of the horizontal section of the wellbore trajectory, i.e., the A target point, and the ending point of the horizontal section of the wellbore trajectory, i.e., the B target point;

[0008] S2 Construct a fracturing well platform coordinate system, translate the coordinates of the A target point to the origin of the axes of the fracturing well platform coordinate system to obtain a translation transformation model, and perform a translation transformation on the coordinates of the B target point according to the translation transformation model;

[0009] S3 rotates the translated B target point to the Y-axis of the coordinate system of the fracturing well platform, obtaining a rotation transformation model;

[0010] S4 obtains the horizontal projection coordinates of the wellbore trajectory and the key point coordinates of the large-scale natural fractures. After transformation using the translation transformation model and the rotation transformation model, the large-scale natural fractures and the wellbore trajectory are displayed in the design coordinate system of the fracturing well platform.

[0011] Further, in S1, the key point coordinates of the designed wellbore trajectory are the coordinates in the horizontal projection coordinate system of the wellbore trajectory or the seismic coordinate system. Both coordinate systems take the positive half-axis of the X-axis as the due east direction and the positive half-axis of the Y-axis as the due north direction. The origin of the horizontal projection coordinate system of the wellbore trajectory is the wellhead of the wellbore trajectory.

[0012] Further, in S1, the seismic coordinate system is Beijing 1954, Xi'an 2000, Xi'an 80, CGCS2000 or WGS84 coordinate.

[0013] Further, in S2, on the horizontal plane projection, with the A target point as the origin of the coordinate axis, the positive half-axis of the X-axis as the due east direction, and the positive half-axis of the Y-axis as the due north direction, a coordinate system of the fracturing well platform is constructed.

[0014] Further, in S2, the translation transformation model is: (X 平 , Y 平 ) = (X - X A , Y - Y A )

[0015] where X and Y are the horizontal and vertical coordinates of any point to be transformed respectively, X A , Y A are the horizontal and vertical coordinates of the A target point respectively, and X 平 , Y 平 are the horizontal and vertical coordinates of any point after translation transformation respectively.

[0016] Further, in S3, the rotation transformation model is:

[0017] When the translated B target point is located in the second and fourth quadrants of the coordinate system of the fracturing well platform, the rotation transformation formula is:

[0018] (X 终 , Y 终 ) = (X 平 cosθ + Y 平 sinθ, Y 平 cosθ - X 平 sinθ).

[0019] When the translated B target point is located in the first and third quadrants of the coordinate system of the fracturing well platform, the rotation transformation formula is:

[0020] (X终 , Y 终 ) = (X 平 cosθ - Y 平 sinθ, Y 平 cosθ + X 平 sinθ).

[0021] Among them, X 终 , Y 终 are respectively the abscissa and ordinate of an arbitrary point to be transformed in the coordinate system of the fracturing well platform; X 平 , Y 平 are respectively the abscissa and ordinate of the arbitrary point after translation transformation, and θ is the included angle between the line connecting the B target point after translation transformation and the origin of the coordinate system of the fracturing well platform and the Y-axis.

[0022] Furthermore, in S3, connect the B target point after translation transformation and the origin of the coordinate system of the fracturing well platform. The included angle between this connection line and the Y-axis is the rotation angle of the B target point after translation transformation, and the radian measure of the rotation angle is calculated using the arctangent function.

[0023] Furthermore, in S3, the calculation of the radian measure of the rotation angle is specifically as follows:

[0024] Then θ = Arctgθ;

[0025] Among them, θ is the included angle between the line connecting the B target point after translation transformation and the origin of the coordinate system of the fracturing well platform and the Y-axis; X B平 , Y B平 are respectively the abscissa and ordinate of the B target point in the coordinate system of the fracturing well platform.

[0026] Furthermore, in S4, the key point coordinates of large-scale natural fractures include the fracture starting point coordinates and the fracture ending point coordinates. Connect the fracture starting point and the fracture ending point to identify the fracture plane shape; when the fracture shape is distorted, connect the fracture starting point and the fracture inflection point, and the fracture ending point in sequence to identify the fracture shape.

[0027] Furthermore, in S4, the key point coordinates of large-scale natural fractures are the coordinates in the seismic coordinate system.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] The present invention provides a method for displaying natural fractures in platform fracturing design. A fracturing well platform coordinate system is established, and a translation transformation model and a rotation transformation model of coordinates are constructed by converting the well depth trajectory into the fracturing well platform coordinate system. The natural fracture data body coordinates can be directly converted into the corresponding coordinates for fracturing design by using the translation transformation model and the rotation transformation model, so as to visually display the natural fractures in the platform fracturing design, realize the comparison between the fracture propagation model in the platform fracturing design and the position of the natural fractures. The present invention can effectively improve the fracturing simulation efficiency and the accuracy of the fracturing plan, judge the risk of the fracturing plan, provide a reliable reference for optimizing the fracturing plan, improve the success rate of the fracturing construction and reduce the casing deformation risk. At present, the construction success rate of the method of the present invention is 100%, and the casing deformation risk is reduced by 10%.

[0030] Furthermore, the method of the present invention is applicable to the preparation of the fracturing plan. Compared with the prior art, it is not necessary to establish a geological model and a fracture model with complex data, and the operation process is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 They are the key points of the wellbore trajectory of the seismic body. The key point O of the wellbore trajectory is the wellhead, A is the A target point, B is the B target point, and the key points C1, C2, D1, D2 of the natural fractures are the starting and ending points of the natural fracture C and the fracture D respectively;

[0032] Figure 2 Horizontal projection diagram of the wellbore trajectory;

[0033] Figure 3 Schematic diagram of the fracturing well platform coordinate system;

[0034] Figure 4 Horizontal transformation effect of the key point coordinates of the wellbore trajectory and the horizontal projection of the wellbore trajectory in the fracturing well platform coordinate system;

[0035] Figure 5 Rotation transformation effect of the key points of the wellbore trajectory;

[0036] Figure 6 Display of the wellbore trajectory and the key points of the natural fractures in the fracturing well platform design coordinate system;

[0037] Figure 7 Flowchart of the technical solution of the present invention;

[0038] Figure 8 Schematic diagram of the seismic coordinates of the wellbore trajectory and the key points C and D of the natural fractures in the example well;

[0039] Figure 9 Horizontal projection diagram of the wellbore trajectory in the example well;

[0040] Figure 10 Coordinates of the key points after translation transformation;

[0041] Figure 11 The key points are transformed by rotation to obtain the coordinates in the fracturing well platform coordinate system;

[0042] Figure 12 The simulation results of hydraulic fractures considering the influence of natural fractures in the fracturing well platform coordinate system. Specific implementation manners

[0043] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation manners.

[0044] In order to improve the accuracy of the fracturing plan, the present invention provides a method for displaying natural fractures in platform fracturing design, which transforms the seismic coordinates of natural fractures or the horizontal projection coordinates of wellbore trajectories into the fracturing platform design coordinates, and loads natural fractures during the fracturing design simulation, as Figures 1 to 7 shown, the specific steps are as follows:

[0045] 1. Record the key point coordinates of the designed wellbore trajectory in the horizontal projection coordinate system of the wellbore trajectory or the seismic coordinate system:

[0046] Among them, the key points of the wellbore trajectory include the wellhead coordinates, the starting point of the horizontal section of the trajectory, i.e., the A target point, and the ending point of the horizontal section of the trajectory, i.e., the B target point. Taking the seismic section projection diagram of Well X as an example, record the projected coordinates of the key points of the wellbore trajectory: including the wellhead (X 0 , Y 0 ), the A target point (X A , Y A ), the B target point (X B , Y B ); specifically, both coordinate systems take the positive half-axis of the X-axis as the due east direction and the positive half-axis of the Y-axis as the due north direction, and the origin of the horizontal projection coordinate system of the wellbore trajectory is the wellhead position;

[0047] Among them, the seismic coordinate system can be the main coordinate systems such as Beijing 1954, Xi'an 2000, Xi'an 80, CGCS2000, WGS84, etc.

[0048] 2. Establish the fracturing well platform coordinate system:

[0049] On the horizontal plane projection, taking the A target point among the key points of the wellbore trajectory as the origin of the coordinate axis (X: 0, Y: 0), the positive half-axis of the X-axis as the due east direction, and the positive half-axis of the Y-axis as the due north direction, construct the fracturing well platform coordinate system. The B target point of the designed well is located on the Y-axis.

[0050] 3. Convert the coordinates of the key points of the designed wellbore trajectory into the fracturing well platform coordinate system;

[0051] 3.1. Perform a translation transformation on the A target point in the horizontal projection coordinate system of the wellbore trajectory or the seismic coordinate system to the origin of the fracturing well platform coordinate system, and the obtained translation transformation formula is:

[0052] (X平 , Y 平 ) = (X - X A , Y - Y A )

[0053] Among them, X and Y are respectively the horizontal and vertical coordinates of any point to be transformed in the horizontal projection coordinate system of the wellbore trajectory or the seismic coordinate system, and X A , Y A are respectively the horizontal and vertical coordinates of the A target point in the horizontal projection coordinate system of the wellbore trajectory or the seismic coordinate system, and X 平 , Y 平 are respectively the horizontal and vertical coordinates of the arbitrary point after translation transformation.

[0054] 3.2. The translation transformation of the coordinates of the B target point in the horizontal projection coordinate system of the wellbore trajectory or the seismic coordinate system according to the above translation transformation formula, and the coordinates of the B target point in the fracturing well platform coordinate system are (X B平 , Y B平 );

[0055] 3.3. Rotate the B target point after translation transformation to the Y-axis of the fracturing well platform coordinate system to facilitate the display of the hydraulic fracture morphology and the natural fracture position. Specifically: Connect the origin to the B target point, and the included angle between the line connecting the origin and the B target point and the Y-axis is θ, and this included angle θ is the rotation angle of the B target point, and the radian of the rotation angle is calculated through the arctangent function;

[0056] The determination of the rotation angle is specifically as follows:

[0057] Then θ = Arctgθ;

[0058] 3.4. Obtain the rotation transformation formula of any point to be transformed in the fracturing well platform coordinate system after translation transformation according to the rotation angle, specifically as follows:

[0059] When the B target point after translation transformation is located in the second and fourth quadrants of the fracturing well platform coordinate system, the rotation transformation formula is:

[0060] (X 终 , Y 终 ) = (X 平 cosθ + Y 平 sinθ, Y 平 cosθ - X 平 sinθ).

[0061] When the B target point after translation transformation is located in the first and third quadrants of the fracturing well platform coordinate system, the rotation transformation formula is:

[0062] (X 终 , Y 终 ) = (X 平 cosθ - Y 平sinθ, Y 平 cosθ + X 平 sinθ).

[0063] 4. Obtain the horizontal projection coordinates of the wellbore trajectory and the key point coordinates of large-scale natural fractures in the seismic coordinate system, and use the translation transformation formula and rotation transformation formula to display the wellbore trajectory and large-scale natural fractures in the fracturing well platform design coordinate system.

[0064] Specifically, the key point coordinates of large-scale natural fractures include the fracture starting point coordinates and the fracture ending point coordinates. The line connecting the fracture starting point and the fracture ending point is used to identify the fracture plane shape; when the fracture shape is distorted, the inflection points of the fracture shape need to be considered, and the lines connecting the fracture starting point and the fracture inflection points, and the fracture ending point are used to identify the fracture shape in turn.

[0065] 5. Calculate the distance from target point A to target point B in the horizontal projection coordinate system of the wellbore trajectory or the seismic volume coordinate system, that is, the horizontal section length L:

[0066]

[0067] After the rotation transformation is completed, if the X coordinate of target point B is 0 and the absolute value of the Y coordinate is equal to the distance L from target point A to target point B, it proves that the coordinate transformation result is accurate.

[0068] Example 1

[0069] A certain well is a shale gas fracturing well. According to the seismic interpretation section results, there are a large number of natural fractures around the wellbore, the fracture size is large, and there are risks in the fracturing construction.

[0070] As Figure 8 shown, taking the seismic section projection diagram of this well as an example, record the projection coordinates of the key points of the wellbore trajectory: wellhead (X 0 : 462599.95, Y 0 : 3272226.81), target point A (X A : 463217.9, Y A : 3271941), target point B (X B : 463372.72, Y B : 3270270.08); the start and end point coordinates of natural fracture C and natural fracture D: C1 (X C1 : 463127, Y C1 : 3271487), C2 (X C2 : 463286, Y C2 : 3271388), D1 (X D1 : 463201, Y D1 : 3271704), D2 (X D2 : 462908, Y D2: 3271260). As Figure 9 shown, it is the horizontal projection coordinates of the wellbore trajectory.

[0071] The coordinates of target point A are (X A : 463217.9, Y A : 3271941). For any point coordinates (X, Y) in the seismic coordinate system, the translation transformation is (X - 463217.9, Y - 3271941). After the transformation, the translation conversion coordinates of the key points of the wellbore trajectory of Well X are: at the wellhead (X 0平 : -617.95, Y 0平 : 285.81), at target point A (X A平 : 0, Y A平 : 0), at target point B (X B平 : 154.82, Y B平 : -1670.92); the translation conversion coordinates of the key points of the natural fractures are: C1 (X C1平 : -90.9, Y C1平 : -454), C2 (X C2平 : 68.1, Y C2平 : -553), D1 (X D1平 : -16.9, Y D1平 : -237), D2 (X D2平 : -309.9, Y D2平 : -681).

[0072] The angle θ between the line connecting the wellhead and target point B and the y-axis.

[0073] (θ is an acute angle).

[0074] The radian measure of the angle θ is: Arctgθ = 0.09239175.

[0075] As Figure 10 shown, after the translation transformation, target point B is located in the fourth quadrant.

[0076] Target point B is located in the fourth quadrant, and the final coordinate transformation is (xcosθ + ysinθ, ycosθ - xsinθ).

[0077] As Figure 11 shown, after the rotation transformation, the coordinates of the wellbore trajectory of Well X and the key points of natural fractures C and D are: at the wellhead (X 0终 : -588.95, Y 0终 : 341.60), at target point A (X A终 : 0, Y A终 : 0), at target point B (X B终 : 0, Y B终 : -1678.08); C1 (XC1终 : -132.40, Y C1终 : -443.68), C2(X C2终 : 16.79, Y C2终 : -556.92), D1(X D1终 : -38.69, Y D1终 : -234.43), D2(X D2终 : -371.41, Y D2终 : -649.50).

[0078] Calculate the distance L from the wellhead to the B target point:

[0079]

[0080] The absolute value of the Y coordinate of the B target point is 1678.08, and the coordinate transformation is accurate.

[0081] As Figure 12 shown, according to the simulation results, due to fracture filtration loss, the fracture length decreases and the fracture width decreases significantly, making it difficult to predict proppant addition. According to the simulation results, optimize the pumping program of the fracturing design, and use linear gel as the preflush fluid to improve the fracture formation performance. Guide the fracturing construction according to the optimized fracturing design, and the fracturing construction of this well is smooth, with a daily gas production of 300,000 cubic meters.

Claims

1. A method for displaying natural fractures in platform fracturing design, characterized in that, the specific steps are as follows: S1 Obtain the key point coordinates of the wellbore trajectory of the design well. The key points of the wellbore trajectory include the starting point of the horizontal section of the wellbore trajectory, i.e., the A target point, and the ending point of the horizontal section of the wellbore trajectory, i.e., the B target point; S2 Construct a fracturing well platform coordinate system, translate the coordinates of the A target point to the origin of the coordinate axis of the fracturing well platform coordinate system to obtain a translation transformation model, and perform a translation transformation on the coordinates of the B target point according to the translation transformation model; S3 Rotate the translated B target point to the Y axis of the fracturing well platform coordinate system to obtain a rotation transformation model; S4 Obtain the horizontal projection coordinates of the wellbore trajectory and the key point coordinates of large-scale natural fractures, and display the large-scale natural fractures and the wellbore trajectory in the fracturing well platform design coordinate system after transformation using the translation transformation model and the rotation transformation model.

2. The method for displaying natural fractures in platform fracturing design according to claim 1, characterized in that, in S1, the key point coordinates of the wellbore trajectory of the design well are the coordinates in the horizontal projection coordinate system of the wellbore trajectory or the seismic coordinate system. Both coordinate systems take the positive half-axis of the X axis as the due east direction and the positive half-axis of the Y axis as the due north direction. The origin of the horizontal projection coordinate system of the wellbore trajectory is the wellhead of the wellbore trajectory.

3. The method for displaying natural fractures in platform fracturing design according to claim 1, characterized in that, in S1, the seismic coordinate system is Beijing 1954, Xi'an 2000, Xi'an 80, CGCS2000 or WGS84 coordinate.

4. The method for displaying natural fractures in platform fracturing design according to claim 1, characterized in that, in S2, on the horizontal plane projection, with the A target point as the origin of the coordinate axis, the positive half-axis of the X axis as the due east direction, and the positive half-axis of the Y axis as the due north direction, construct a fracturing well platform coordinate system.

5. The method for displaying natural fractures in platform fracturing design according to claim 1, characterized in that, In S2, the translation transformation model is: (X 平 , Y 平 ) = (X - X A , Y - Y A ) Among them, X and Y are the horizontal and vertical coordinates of any point to be transformed, respectively. X A , Y A are the horizontal and vertical coordinates of target point A, respectively. X 平 , Y 平 are the horizontal and vertical coordinates of the point after translation transformation, respectively.

6. The method for displaying natural fractures in platform fracturing design according to claim 1, characterized in that, in S3, the rotation transformation model is: When the translated B target point is in the second and fourth quadrants of the fracturing well platform coordinate system, the rotation transformation formula is: (X 终 , Y 终 ) = (X 平 cosθ + Y 平 sinθ, Y 平 cosθ - X 平 sinθ) When the translated B target point is in the first and third quadrants of the fracturing well platform coordinate system, the rotation transformation formula is: (X 终 , Y 终 ) = (X 平 cosθ - Y 平 sinθ, Y 平 cosθ + X 平 sinθ) Among them, X 终 , Y 终 are respectively the abscissa and ordinate of an arbitrary point to be transformed in the coordinate system of the fracturing well platform; X 平 , Y 平 are respectively the abscissa and ordinate of the arbitrary point after translation transformation, and θ is the angle between the line connecting the transformed B target point and the origin of the fracturing well platform coordinate system and the Y-axis.

7. The method for displaying natural fractures in platform fracturing design according to claim 6, characterized in that, in S3, connect the translated B target point with the origin of the fracturing well platform coordinate system. The included angle between the connection line and the Y axis is the rotation angle of the translated B target point, and the radian measure of the rotation angle is calculated using the arctangent function.

8. The method for displaying natural fractures in platform fracturing design according to claim 7, characterized in that, in S3, the calculation of the radian measure of the rotation angle is specifically: Then θ = Arctgθ; Where, θ is the angle between the line connecting the B target point after translation transformation and the origin of the coordinate system of the fracturing well platform and the Y-axis; X B平 , Y B平 are the abscissa and ordinate of the B target point in the coordinate system of the fracturing well platform, respectively.

9. The method for displaying natural fractures in platform fracturing design according to claim 1, characterized in that, In S4, the key point coordinates of large-scale natural fractures include the fracture starting point coordinates and the fracture ending point coordinates. The line connecting the fracture starting point and the fracture ending point is used to identify the planar shape of the fracture. When the fracture shape is distorted, the lines connecting the fracture starting point and the fracture inflection point, and the fracture ending point are used to identify the fracture shape in sequence.

10. A method for displaying natural fractures in platform fracturing design according to claim 9, characterized in that, in S4, the key point coordinates of large-scale natural fractures are the coordinates in the seismic coordinate system.

Images