Method for determining seismic section along well trajectory

Abstract

The invention belongs to the technical field of oil-gas exploration and development, and particularly relates to a method for determining a seismic section along a well trajectory. On the basis of reserving seismic traces corresponding to virtual control points located at grid measuring line intersection points, seismic trace information around the virtual control points which are arranged along a well trajectory and do not coincide with the grid measuring line intersection points is utilized, and a synthetic seismic trace capable of representing seismic trace information at other positions along the well trajectory is obtained; the finally obtained seismic trace along the well trajectory not only can ensure that the subsequent determination of the seismic section is not influenced by the horizontal distance and the stratigraphic dip angle between the actual position of the seismic trace and the well trajectory, but also can save the calculation cost. When the synthetic seismic channel is calculated, the actual reference seismic channel data after depth correction is adopted; therefore, the waveform and amplitude information of the synthesized seismic trace more accords with the actual stratum information of the position of the well trajectory, thereby providing an accurate reference basis for the design of the horizontal section well trajectory, and improving the accuracy of seismic profile extraction.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas exploration and development, and in particular relates to a method for determining a seismic profile along a well trajectory. Background Art

[0002] Unconventional resources such as shale gas are an important supplement to conventional resources. The development of shale gas is an important way to alleviate energy and environmental pressures. According to the statistical analysis of Ou Jugang and others from the Geophysical Exploration Key Laboratory of CNPC, the penetration quality of the best target in the horizontal section of shale gas is the key to obtaining high-yield wells and forming economies of scale. The horizontal section drilling trajectory direction of horizontal wells deployed for unconventional resources usually mainly considers the horizontal principal stress direction of the target layer and the distribution range of the sweet spot area, and the initial model design of the horizontal well trajectory needs to be based on the target window depth and formation apparent dip information obtained from the seismic profile interpretation, that is, after determining the coordinates of the designed wellhead and the designed target point, the seismic profile is first extracted from the three-dimensional seismic data body along the well trajectory direction line, and then the seismic response characteristics of the top and bottom of the target window are determined according to the well-seismic calibration. Finally, the initial model of the horizontal section design of the horizontal well is established through the time-depth conversion results. Therefore, in the process of designing the initial model, the reliability of the formation depth and formation dip information in the seismic profile extracted along the well trajectory direction line is the key factor in determining the accuracy of the initial model of the horizontal section design of the horizontal well.

[0003] Since the deployment design of 3D seismic mainly considers underground structural factors, the orientation of the main survey line of 3D seismic is usually designed to be perpendicular to the underground structural trend. The size of the face element depends on the lateral scale and lateral resolution requirements of the target geological body and the investment scale of the acquisition project. In most cases, the direction of the horizontal drilling trajectory will not coincide with the direction of the main survey line or the connecting survey line in the 3D seismic face element grid. According to research data, the current mainstream seismic interpretation software Petrel and GeoFrame use the "near track projection" method to extract the seismic profile along the well trajectory, that is, the actual seismic trace closest to the well trajectory is projected as the data extracted from the profile along the well trajectory. Since most basins in China have undergone multiple stages of tectonic transformation and adjustment in the geological history, taking the marine LMX Formation in the southern Sichuan Basin and the terrestrial QFY Formation in northeastern Sichuan as examples, most horizontal wells deployed for shale gas or tight sand will have varying degrees of formation inclination or micro-structures such as small faults in the horizontal section. In addition, high-quality shale sections have geological characteristics such as thin thickness, rapid changes in formation dip, and development of micro-structures and micro-fractures. Therefore, when the target layer is tilted, the seismic profiles along the well trajectory extracted using the current method often show regular step-like faults of the seismic phase axis, which affects the stratigraphic comparison and formation dip calculation, reduces the design accuracy of the horizontal well trajectory, and leads to a higher risk of off-target and out-of-layer during subsequent drilling.

[0004] A Chinese invention patent with application publication number CN102943669A proposes a technical solution of "a high-precision depth domain random simulation inversion method suitable for horizontal well horizontal section drilling trajectory design". By establishing a solid model, the selected typical wells are calibrated and fine-tuned to establish a well control velocity field, thereby improving the prediction accuracy of the target layer depth of the horizontal well trajectory. The disadvantage of this method is that it does not solve the vertical error caused by the influence of the formation inclination when the plane position of the data channel in the inversion result is not on the designed well trajectory, thereby resulting in inaccurate target layer depth information. The Chinese invention patent with application publication number CN114494571A proposes a technical solution of "method, device, equipment and medium for extracting arbitrary profiles from three-dimensional seismic data volumes". This solution does not take into account the influence of changes in stratum dip angles when performing weighted average calculations of seismic trace data of all CMP points within a given facet radius, resulting in the inability to achieve in-phase superposition in the weighted average calculation. The larger the given facet radius, the greater the difference in the lateral distance and azimuth values ​​of the seismic traces involved in the calculation from the center of the given facet, and the worse the effect of in-phase superposition. Therefore, the wave group characteristics of the newly generated synthetic seismic traces and the amplitude preservation of the reflected wave amplitude are poor, and the stratum depth corresponding to the reflection phase axis is also inaccurate. Summary of the invention

[0005] The purpose of the present invention is to provide a method for determining a seismic profile along a well trajectory, so as to solve the problem of poor accuracy caused by the influence of the horizontal distance between the actual position of the seismic trace and the well trajectory line and the formation inclination when determining the seismic profile along the well trajectory in the prior art.

[0006] In order to achieve the above object, the present invention provides a method for determining a seismic profile along a well trajectory, characterized in that it comprises the following steps:

[0007] According to the plane position of the target point designed for the horizontal well, each virtual control point is determined along the horizontal well trajectory according to the preset spacing;

[0008] If the virtual control point is located at the intersection of the grid lines, the seismic trace at the intersection of the grid lines is used as the seismic trace of the seismic profile at the virtual control point; otherwise, a synthetic seismic trace is obtained based on the actual reference seismic trace corresponding to the virtual control point, and is used as the seismic trace of the seismic profile at the virtual control point;

[0009] The seismic traces at all virtual control points are sorted to obtain the seismic profile determined along the well trajectory.

[0010] The beneficial effects of the above technical solution are: on the basis of retaining the seismic traces corresponding to the virtual control points located at the intersection of the grid lines (that is, the actual positions of the seismic traces with almost no difference in horizontal distance from the well trajectory), synthetic seismic traces of the virtual control points set along the well trajectory that do not coincide with the intersection of the grid lines are obtained as seismic traces that can characterize the seismic trace information at other positions along the well trajectory; all the seismic traces finally obtained along the well trajectory can not only ensure that the actual positions of the seismic traces are not affected by the horizontal distance and the formation inclination between the well trajectory and the well trajectory when the seismic profile is determined later, but also save calculation costs.

[0011] Furthermore, the method of obtaining the synthetic seismic trace according to the actual reference seismic trace corresponding to the virtual control point is as follows:

[0012] According to the horizontal distance between the virtual control point and the corresponding actual reference seismic trace, the weight coefficient corresponding to each actual reference seismic trace is obtained; according to the weight coefficient, the weighted average operation is performed on each actual reference seismic trace to obtain the synthetic seismic trace at the virtual control point.

[0013] The beneficial effect of the above technical solution is that when calculating the synthetic seismic trace, the seismic trace information of the positions around the virtual control points set along the well trajectory that do not coincide with the intersection of the grid survey lines is utilized and fully considered, and the obtained synthetic seismic trace is more consistent with the actual stratigraphic information at the location of the well trajectory.

[0014] Furthermore, the actual reference seismic trace is determined as follows:

[0015] According to the seismic data in the study area, the original data of the actual reference seismic traces and the depth information of the constraint layer corresponding to each actual reference seismic trace are obtained;

[0016] According to the depth correction amount corresponding to each actual reference seismic trace obtained through the depth information of the constraint layer, depth correction is performed on the original data of the actual reference seismic trace to obtain the actual reference seismic trace.

[0017] The beneficial effect of the above technical solution is that when calculating the synthetic seismic trace, the actual reference seismic trace data after depth correction is used to make the waveform and amplitude information of the synthetic seismic trace further consistent with the actual stratigraphic information at the location of the well trajectory, thereby improving the accuracy of seismic profile extraction.

[0018] Furthermore, the preset spacing is determined according to the size of the bin grid of the original seismic data; if the bin grid sizes of the main survey line direction and the connecting survey line direction corresponding to the original seismic data are inconsistent, the preset spacing is determined according to the size of the smaller bin grid.

[0019] The beneficial effects of the above technical solution are: it is convenient to compare the new seismic trace data generated according to the virtual control points with the original data; and the actual seismic trace spacing (the spacing between the intersection points of the grid survey lines of the original seismic data) determines the plane sampling interval for calculating the seismic trace data. If the spacing between the virtual control points is too small, the reliability of the synthetic seismic trace data obtained through the actual seismic trace data cannot be guaranteed. Therefore, determining the spacing between the virtual control points according to the facet size of the original seismic data can ensure the accuracy of the seismic trace data newly generated according to the virtual control points.

[0020] Furthermore, the actual reference seismic trace corresponding to the virtual control point is located at the intersection of two main survey lines and two contact survey lines that are closest to the virtual control point.

[0021] Furthermore, the depth correction amount corresponding to each actual reference seismic trace is obtained by performing bilinear interpolation on the position of each actual reference seismic trace and the depth information of the corresponding constraint layer.

[0022] Furthermore, each virtual control point is arranged at equal intervals.

[0023] The beneficial effects of the above technical solution are: it can adapt to the currently common equally spaced regular grid elements, which helps to set a unified scale to observe the shape and size of underground targets without local sparseness or over-density; and it is easy to match the spacing of virtual control points with the grid of the original data, which can not only ensure the quality of the generated new data, but also help to compare them with each other.

[0024] Furthermore, the depth correction method for the original data of the actual reference seismic trace is as follows:

[0025] The difference between the depth value of the constraint layer of the preset virtual control point and the depth value of the constraint layer in a certain actual reference seismic trace is used as the depth correction value of the actual reference seismic trace. The original data of the actual reference seismic trace is subjected to static correction processing using the depth correction value to obtain the actual reference seismic trace after depth correction.

[0026] Furthermore, the weight coefficient is calculated as follows:

[0027] d n =1 / d a,b +1 / d a,b+1 +1 / d a+1,b+1 +1 / d a+1,b

[0028]

[0029]

[0030]

[0031]

[0032] Among them, d a,b d a,b+1 d a+1,b+1 d a,b+1 are the horizontal distances between the virtual control points and their corresponding actual reference seismic traces; d n is d a,b d a,b+1 d a+1,b+1 and d a,b+1 The sum of the reciprocals of a,b 、w a,b+1 、w a+1,b+1 、w a,b+1 are the weight coefficients corresponding to the actual reference seismic traces.

[0033] Furthermore, the weighted average operation is performed on each actual reference seismic trace to obtain the synthetic seismic trace at the virtual control point in the following manner:

[0034] p n,m =w a,b *c a,b,m +w a,b+1 *c a,b+1,m +w a+1,b+1 *c a+1,b+1,m +w a+1,b *c a+1,b,m

[0035] Where M is the number of sampling points of a single channel of seismic records, 1≤m≤M; p n,m is the virtual control point P n The sample amplitude value of the synthetic seismic trace corresponding to the sampling point m; c a,b,m 、c a,b+1,m 、c a+1,b+1,m 、c a,b+1,m are respectively the sample point amplitude values ​​of each actual reference seismic trace corresponding to the sampling point m. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a flowchart of a method for determining a seismic profile along a well trajectory in an embodiment of the method for determining a seismic profile along a well trajectory of the present invention;

[0037] Figure 2 A schematic diagram of designing a horizontal wellhead and a target point position in an embodiment of a method for determining a seismic profile along a well trajectory of the present invention;

[0038] Figure 3 A schematic diagram of virtual control points defined along a well trajectory in an embodiment of a method for determining a seismic profile along a well trajectory of the present invention;

[0039] Figure 4a A schematic diagram of the position of seismic traces used to extract the seismic profile along the well trajectory using the prior art method in the method for determining the seismic profile along the well trajectory of the present invention;

[0040] Figure 4b A schematic diagram of a seismic profile along a well trajectory extracted using a method of the prior art in an embodiment of a method for determining a seismic profile along a well trajectory of the present invention;

[0041] Figure 5 It is a schematic diagram of the interpretation result of the top and bottom of the horizontal segment target window and the midpoint layer of the target window corresponding to the seismic profile along the well trajectory extracted by using the prior art method in the embodiment of the method for determining the seismic profile along the well trajectory of the present invention;

[0042] Figure 6a It is a schematic diagram of a seismic profile along the main survey line 1455 through Trace 10 extracted by using the prior art method in the embodiment of the method for determining the seismic profile along the well trajectory of the present invention;

[0043] Figure 6b It is a schematic diagram of a seismic profile in the direction of the contact survey line 1327 passing through Trace 10 extracted by using the prior art method in the embodiment of the method for determining the seismic profile along the well trajectory of the present invention;

[0044] Figure 7 A schematic diagram of actual reference seismic trace positions corresponding to virtual control points in an embodiment of a method for determining a seismic profile along a well trajectory of the present invention;

[0045] Figure 8 A schematic diagram of the positions of actual reference seismic traces and the depth information of corresponding constraint layers in an observation system used for three-dimensional seismic data of a certain region in an embodiment of the method for determining a seismic profile along a well trajectory of the present invention;

[0046] Fig. 9 A schematic diagram of the horizontal distance between a virtual control point and its corresponding actual reference seismic trace in an embodiment of the method for determining a seismic profile along a well trajectory of the present invention;

[0047] Fig.10 It is a schematic diagram of the method for determining the seismic profile along the well trajectory of the present invention using bilinear interpolation to the constraint layer depth value;

[0048] Fig.11 A schematic diagram of a seismic profile determined along a well trajectory obtained by sequentially sorting and displaying the seismic traces at all virtual control points in an embodiment of a method for determining a seismic profile along a well trajectory of the present invention;

[0049] Fig.12It is a schematic diagram of the interpretation results of the top and bottom of the horizontal segment target window and the midpoint layer of the target window corresponding to the seismic profile determined along the well trajectory line obtained in the embodiment of the method for determining the seismic profile along the well trajectory of the present invention. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0051] Embodiment of a method for determining a seismic profile along a well trajectory

[0052] This embodiment provides a technical solution for a method for determining a seismic profile along a well trajectory. Figure 1 , including the following steps:

[0053] 1) According to the plane position of the horizontal well design target, each virtual control point is determined along the horizontal well trajectory according to the preset spacing;

[0054] The planar position of the horizontal well design target is obtained by collecting basic data. In this embodiment, the collected basic data include the original three-dimensional seismic data in the study area, the original three-dimensional seismic surface grid of the work area, the designed horizontal wellhead and the designed target coordinate data; wherein, the original three-dimensional seismic data in the study area and the original three-dimensional seismic surface grid of the work area are both original seismic data; the preset spacing is determined according to the size of the surface grid of the original seismic data; if the surface grid sizes of the main survey line direction and the connecting survey line direction corresponding to the original seismic data are inconsistent, the preset spacing is determined according to the size of the smaller surface grid; in this embodiment, the virtual control points are set at equal intervals, and the preset spacing is consistent with the size of the smaller surface grid in the original seismic data in different survey line directions (i.e., the main survey line direction and the connecting survey line direction corresponding to the original seismic data).

[0055] Therefore, the preset spacing between each virtual control point set according to the size of the bin grid of the original seismic data can facilitate the comparison of the new seismic trace data generated according to the virtual control points with the original data; and the actual seismic trace spacing (the spacing between the grid survey line intersections of the original seismic data) determines the plane sampling interval for calculating the seismic trace data. If the spacing between the virtual control points is too small, the reliability of the synthetic seismic trace data obtained through the actual seismic trace data cannot be guaranteed. Therefore, determining the spacing between the virtual control points according to the bin size of the original seismic data can ensure the accuracy of the seismic trace data newly generated according to the virtual control points; the equal spacing between each virtual control point can adapt to the currently common equal-interval regular grid bins, which is helpful to set a unified scale to observe the shape and size of underground targets without local sparseness or over-density; and the spacing between the virtual control points and the original data (i.e., the spacing between the grid survey lines of the original seismic data) adopts the same grid size, which is convenient for matching the spacing between the virtual control points with the grid of the original data, which can not only ensure the quality of the generated new data, but also facilitate comparison between them. The same seismic trace spacing (the spacing between the virtual control points and the grid of the original data corresponds to the respective seismic trace spacing) is also helpful for switching the display in the same window.

[0056] like Figure 2 As shown, in this embodiment, according to the collected basic data, the azimuth of the main survey line of the original 3D seismic bin grid in the work area is 125° (0° in the north direction and positive in the clockwise direction), the bin size is 25m*25m, and the azimuth of the horizontal well trajectory between the designed target points is 150°; the design of the horizontal wellhead and the design target point position is referenced Figure 2 , the grid survey line includes the main survey line and the connecting survey line. The main survey line number of the horizontal wellhead plane position is designed to be 1465, and the connecting survey line number is 1310. The main survey line number of the target plane position is designed to be 1460, and the connecting survey line number is 1318. The designed target depth is -2620m above sea level; the main survey line number of the target plane position is designed to be 1439, and the connecting survey line number is 1359. The designed target depth is -2668m above sea level. With the bin size (i.e. 25m) as the preset spacing, the horizontal section length between the designed targets is 1075m, which contains 42 seismic traces in total. Figure 3 As shown in Figure 1, the position of the target plane in design I is taken as the reference point, and virtual control points are defined along the well trajectory at intervals of 25 m. The positions of the defined virtual control points are as follows: Figure 3 shown.

[0057] According to the logging interpretation results of the pilot well and the well seismic calibration results, the seismic wave group characteristics of the top of the sweet spot target window are manifested as the lower edge of the medium-low frequency and medium-strong wave trough reflection, and the seismic wave group characteristics of the bottom of the target window are manifested as the zero phase position of the upper edge of the medium-low frequency and strong amplitude peak reflection. The top and bottom thickness of the target window is 8m; refer to Figure 4a , Figure 4b , the existing technology method is used to extract the seismic profile along the well trajectory and interpret the top and bottom layers of the target window according to the calibration results. The interpretation results of the top and bottom layers of the horizontal section target window and the midpoint layer of the target window are as follows Figure 5 As shown. From the results, it can be seen that in the seismic profile along the horizontal well trajectory extracted using the current method, there are obvious dislocations in the seismic reflection phase axis. For example, the difference in the apparent dip angles of adjacent tracks between the target window midpoints of Trace8 and Trace12 in the seismic profile extracted along the well trajectory is more than 10°, and the difference in the altitude of the target window midpoints of adjacent tracks is more than 3m. The seismic wave group shows obvious micro-fracture development characteristics. However, from the seismic profile along the main survey line (main survey line 1455) and the connecting survey line (connecting survey line 1327) through Trace10, it can be seen (as shown in Figure 6a , Figure 6b The phase axis in the vicinity is smooth and continuous, with no obvious fault development features. Figure 4b The event axis misalignment shown in Figure 4a The actual position of the seismic trace shown is caused by the horizontal distance between the well trajectory and the dip angle of the target layer; since the midpoint depth information of the target window and the apparent dip angle information of the target layer extracted by the current method along the horizontal well trajectory have obvious errors, it is impossible to design the horizontal drilling trajectory based on them, so the quality of the seismic profile along the horizontal well trajectory needs to be improved. According to the actual seismic data and well-seismic calibration results, it is found that the strong amplitude peak reflection of the mudstone bottom interface below the target window layer is stably distributed in the whole area and can be continuously tracked, and it is defined as the constraint layer.

[0058] 2) If the virtual control point is located at the intersection of the grid lines, the seismic trace at the intersection of the grid lines is used as the seismic trace of the seismic profile at the virtual control point; otherwise, a synthetic seismic trace is obtained based on the actual reference seismic trace corresponding to the virtual control point, and is used as the seismic trace of the seismic profile at the virtual control point;

[0059] The seismic traces at all virtual control points are sorted to obtain the seismic profile determined along the well trajectory.

[0060] By observing the plane position distribution of virtual control points, we can know (such as Figure 3 As shown in the figure, the plane positions of the design I target and the design II target are the intersection points of the grid lines. It can be seen that the points P1 and P 43 The actual seismic trace at the plane position of the point is used as the seismic trace data at its virtual control point. 42 The plane position of a point is different from the coordinates of the midpoint of the seismic grid bin where it is located;

[0061] When the virtual control point is located at the intersection of the grid lines, the actual seismic trace at the intersection of the grid lines is the seismic trace of the seismic profile extracted along the horizontal well trajectory at the virtual control point, and there is no need to calculate the synthetic seismic trace separately, thereby saving calculation cost; if the plane position of the virtual control point does not coincide with the intersection of the grid lines, then in this embodiment, the positions of the four actual reference seismic traces are determined by the intersection of the main lines and the connecting lines near the virtual point, that is, the actual reference seismic trace corresponding to the virtual control point is located at the intersection of the two main lines and the two connecting lines closest to the virtual control point, such as Figure 7 As shown; synthetic seismic traces are obtained based on the actual reference seismic trace correlation data at the positions of four actual reference seismic traces.

[0062] It can be seen that the method for determining the seismic profile along the well trajectory of this embodiment can retain the seismic trace corresponding to the virtual control point located at the intersection of the grid lines (that is, the actual position of the seismic trace with almost no difference in horizontal distance from the well trajectory), and utilize the seismic trace information around the virtual control point set along the well trajectory that does not overlap with the intersection of the grid lines, to obtain a synthetic seismic trace that can characterize the seismic trace information at other positions along the well trajectory; the seismic traces finally obtained along the well trajectory can ensure that the subsequent determination of the seismic profile is not affected by the horizontal distance between the actual position of the seismic trace and the well trajectory and the formation inclination, and can also save computing costs.

[0063] In this embodiment, the calculation of the synthetic seismic trace needs to use the actual reference seismic trace data after depth correction. Therefore, the actual reference seismic trace is determined as follows:

[0064] According to the seismic data in the study area, the original data of the actual reference seismic traces and the depth information of the constraint layer corresponding to each actual reference seismic trace are obtained;

[0065] According to the depth correction amount corresponding to each actual reference seismic trace obtained through the depth information of the constraint layer, the original data of the actual reference seismic trace is depth-corrected to obtain the actual reference seismic trace. In this embodiment, the difference between the depth value of the constraint layer of the preset virtual control point and the depth value of the constraint layer in a certain actual reference seismic trace is used as the depth correction value of the actual reference seismic trace. The original data of the actual reference seismic trace is statically corrected by using the depth correction value to obtain the actual reference seismic trace after depth correction.

[0066] Specifically, the depth correction amount corresponding to each actual reference seismic trace is obtained by performing bilinear interpolation on the position of each actual reference seismic trace and the depth information of the corresponding constraint layer. Bilinear interpolation, as an interpolation algorithm in numerical analysis, is widely used in signal processing, digital image and video processing, etc. In this embodiment, reference is made to Figure 8, taking the observation system used for the original three-dimensional seismic data of a certain area as an example, when the azimuth of the main survey line is 125° (0° in the north direction and positive in the clockwise direction), x a,b ,y a,b 、z a,b Represents the actual reference seismic trace S a,b The horizontal coordinate, vertical coordinate and depth value of the constraint layer (i.e. the depth information of the constraint layer) at Represents bilinear interpolation channel P n,b The horizontal coordinate, vertical coordinate and constraint layer depth value (such as Figure 8 shown), with Represents the virtual control point P n The horizontal coordinate, vertical coordinate and constraint layer depth value at , and so on, we can get the following relationship:

[0067]

[0068]

[0069]

[0070] Similarly, we can calculate and The expression of

[0071]

[0072]

[0073] Finally get

[0074]

[0075] Then the virtual control point P n The constraint layer bit depth value at As a virtual control point P n The depth correction value corresponding to the actual reference seismic trace at .

[0076] After obtaining the actual reference seismic trace data after depth correction of the virtual control point, the method of obtaining the synthetic seismic trace according to the actual reference seismic trace corresponding to the virtual control point is as follows:

[0077] According to the horizontal distance between the virtual control point and its corresponding actual reference seismic trace, the weight coefficient corresponding to each actual reference seismic trace is obtained; according to the weight coefficient, the weighted average operation is performed on each actual reference seismic trace to obtain the synthetic seismic trace at the virtual control point.

[0078] refer to Fig. 9 , the weight coefficient is calculated as:

[0079] d n =1 / d a,b +1 / d a,b+1 +1 / d a+1,b+1 +1 / d a+1,b

[0080]

[0081]

[0082]

[0083]

[0084] Among them, d a,b d a,b+1 d a+1,b+1 d a,b+1 are the horizontal distances between the virtual control points and their corresponding actual reference seismic traces; d n is d a,b d a,b+1 d a+1,b+1 and d a,b+1 The sum of the reciprocals of a,b 、w a,b+1 、w a+1,b+1 、w a,b+1 are the weight coefficients corresponding to the actual reference seismic traces.

[0085] Compared with the original seismic trace data, the waveform and amplitude information of the generated synthetic seismic trace are more consistent with the actual stratigraphic information at the location of the well trajectory, which is conducive to more clearly displaying the stratigraphic micro-structure and micro-fracture development information along the well trajectory, thereby providing an accurate reference basis for the design of the horizontal section of the horizontal well trajectory.

[0086] In this embodiment, the distance from point P2 to point P 42 The bilinear interpolation method is used to determine the actual reference seismic traces after depth correction corresponding to each virtual control point whose plane position is not at the intersection of the grid survey line, and the weight coefficient is calculated according to the plane distance; 11 For example, the corresponding actual reference seismic traces are located at S 1455,1326 , S 1455,1327 , S 1456,1327 , S 1456,1326 The corresponding constraint layer depth values ​​are z 1455,1326 =-2632m,z 1455,1327 =-2634m,z 1456,1327 =-2638m,z 1456,1326 =-2637m, using the bilinear interpolation method, we can know that P 11,1326 The constraint layer depth value is z11,1326 =-2634.12m, P 11,1327 The constraint layer depth value is z 11,1327 =-2635.7m, so P is calculated 11 The constraint layer depth value is z 11 =-2635.54m(e.g. Fig.10 As shown), the depth correction values ​​of each actual reference seismic trace are e 1455,1326 =-3.54m, e 1455,1327 =-1.46m, e 1456,1327 =-1.54m, e 1456,1326 =2.46m, and the actual reference seismic traces obtained after depth correction based on the above values ​​are named C 1455,1326 , C 1455,1327 , C 1456,1327 , C 1456,1326 .

[0087] In this embodiment, a weighted average operation is performed on each actual reference seismic trace to obtain a synthetic seismic trace at the virtual control point in the following manner:

[0088] p n,m =w a,b *c a,b,m +w a,b+1 *c a,b+1,m +w a+1,b+1 *c a+1,b+1,m +w a+1,b *c a+1,b,m

[0089] Where M is the number of sampling points of a single channel of seismic records, 1≤m≤M; p n,m is the virtual control point P n The sample amplitude value of the synthetic seismic trace corresponding to the sampling point m; c a,b,m 、c a,b+1,m 、c a+1,b+1,m 、c a,b+1,m are the sample point amplitude values ​​of each actual reference seismic trace corresponding to the sampling point m; the virtual control point P 11 The horizontal distances from the corresponding actual reference seismic traces are d 1455,1326 =25.1m,d 1455,1327 =10.6m,d 1456,1327 =14.4m,d 1456,1326 =26.9m. According to the above weighted average calculation formula, the weight coefficients of the actual reference seismic traces are w 1455,1326 =0.17, w 1455,1327 =0.39, w 1457,1326 =0.29, w 1456,1326 =0.15, so we know that the virtual control point P 11The sample point amplitude value of the synthetic seismic trace corresponding to the sampling point m is:

[0090] p 11,m =0.17*C 1455,1326,m +0.39*C 1455,1327,m +0.29*C 14561327,m +0.15*C 1456,1326,m

[0091] From this, the virtual control point P can be determined 11 The synthetic seismic trace obtained by weighted average of the layer constraints can be obtained by this method. The virtual control point P2 to P 42 Synthesized seismic traces at points; Seismic traces at all virtual control points, i.e., virtual control points P1 and P 43 The actual seismic trace at point P and the virtual control point P2 to P 42 The synthetic seismic traces at the points are displayed in sequence, and the final seismic profile determined along the well trajectory can be obtained, such as Fig.11 As shown in the figure, from the interpretation results of the top and bottom of the horizontal section target window and the midpoint of the target window, it can be seen that after the horizon constraint correction and weighted average operation, the seismic phase axis is smooth and continuous, the microstructural morphology is clear, the seismic reflection amplitude information has better amplitude preservation, the difference in the apparent dip angle of adjacent layers of the target window midpoint connection line does not exceed ±2.45°, and the difference in the altitude of adjacent layers does not exceed ±2.4m (such as Fig.12 It is consistent with the characteristics of the seismic profile observation results in the direction of the main survey line and the connecting line, and can provide accurate and reliable target window layer depth and target layer apparent dip angle information for the horizontal section drilling trajectory design, laying a foundation for ensuring that the designed well trajectory passes through the middle of the target window and improving the drilling rate of high-quality reservoirs.

[0092] The present invention has the following characteristics:

[0093] 1) On the basis of retaining the seismic traces corresponding to the virtual control points located at the intersection of the grid lines (i.e., the actual positions of the seismic traces with almost no difference in horizontal distance from the well trajectory), the seismic trace information around the virtual control points set along the well trajectory that do not coincide with the intersection of the grid lines is used to obtain synthetic seismic traces that can represent the seismic trace information at other positions along the well trajectory. The seismic traces finally obtained along the well trajectory can ensure that the horizontal distance between the actual position of the seismic trace and the well trajectory and the formation dip are not affected when the seismic profile is determined later, and can also save the calculation cost.

[0094] 2) When calculating the synthetic seismic trace, the actual reference seismic trace data after depth correction is used to make the waveform and amplitude information of the synthetic seismic trace further consistent with the actual stratigraphic information at the location of the well trajectory, which is conducive to more clearly displaying the stratigraphic micro-structure and micro-fracture development information along the well trajectory, thereby providing an accurate reference basis for the horizontal well trajectory design of the horizontal section and improving the accuracy of seismic profile extraction.

[0095] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, but do not constitute a limitation to the present invention.

Claims

1. A method for determining a seismic profile along a well trajectory, characterized in that: The steps include: According to the plane position of the target point designed for the horizontal well, each virtual control point is determined along the horizontal well trajectory according to the preset spacing; If the virtual control point is located at the intersection of the grid lines, the seismic trace at the intersection of the grid lines is used as the seismic trace of the seismic profile at the virtual control point; otherwise, a synthetic seismic trace is obtained based on the actual reference seismic trace corresponding to the virtual control point, and is used as the seismic trace of the seismic profile at the virtual control point; The seismic traces at all virtual control points are sorted to obtain the seismic profile determined along the well trajectory.

2. The method for determining a seismic profile along a well trajectory according to claim 1, characterized in that: The method of obtaining the synthetic seismic trace according to the actual reference seismic trace corresponding to the virtual control point is: According to the horizontal distance between the virtual control point and the corresponding actual reference seismic trace, the weight coefficient corresponding to each actual reference seismic trace is obtained; according to the weight coefficient, the weighted average operation is performed on each actual reference seismic trace to obtain the synthetic seismic trace at the virtual control point.

3. The method for determining a seismic profile along a well trajectory according to claim 1 or 2, characterized in that: The actual reference seismic trace is determined as follows: According to the seismic data in the study area, the original data of the actual reference seismic traces and the depth information of the constraint layer corresponding to each actual reference seismic trace are obtained; According to the depth correction amount corresponding to each actual reference seismic trace obtained through the depth information of the constraint layer, depth correction is performed on the original data of the actual reference seismic trace to obtain the actual reference seismic trace.

4. The method for determining a seismic profile along a well trajectory according to claim 1 or 2, characterized in that: The preset spacing is determined according to the size of the bin grid of the original seismic data; if the bin grid sizes of the main survey line direction and the connecting survey line direction corresponding to the original seismic data are inconsistent, the preset spacing is determined according to the size of the smaller bin grid.

5. The method for determining a seismic profile along a well trajectory according to claim 1 or 2, characterized in that: The actual reference seismic trace corresponding to the virtual control point is located at the intersection of two main survey lines and two contact survey lines closest to the virtual control point.

6. The method for determining a seismic profile along a well trajectory according to claim 3, characterized in that: The depth correction amount corresponding to each actual reference seismic trace is obtained by performing bilinear interpolation on the position of each actual reference seismic trace and the depth information of the corresponding constraint layer.

7. The method for determining a seismic profile along a well trajectory according to claim 1 or 2, characterized in that: The virtual control points are set at equal intervals.

8. The method for determining a seismic profile along a well trajectory according to claim 3, characterized in that: The method of depth correction for the original data of the actual reference seismic trace is: The difference between the depth value of the constraint layer of the preset virtual control point and the depth value of the constraint layer in a certain actual reference seismic trace is used as the depth correction value of the actual reference seismic trace. The original data of the actual reference seismic trace is subjected to static correction processing using the depth correction value to obtain the actual reference seismic trace after depth correction.

9. The method for determining a seismic profile along a well trajectory according to claim 2, characterized in that: The weight coefficient is calculated as follows: d n =1 / d a,b +1 / d a,b+1 +1 / d a+1,b+1 +1 / d a+1,b Among them, d a,b ,d a,b+1 ,d a+1,b+1 ,d a,b+1 are the horizontal distances between the virtual control points and their corresponding actual reference seismic traces; d n is d a,b ,d a,b+1 ,d a+1,b+1 and d a,b+1 The sum of the reciprocals of a,b 、w a,b+1 、w a+1,b+1 、w a,b+1 are the weight coefficients corresponding to the actual reference seismic traces.

10. The method for determining a seismic profile along a well trajectory according to claim 2, characterized in that: The method of performing weighted average calculation on each actual reference seismic trace to obtain the synthetic seismic trace at the virtual control point is: p n,m =w a,b *c a,b,m +w a,b+1 *c a,b+1,m +w a+1,b+1 *c a+1,b+1,m +w a+1,b *c a+1,b,m Where M is the number of sampling points of a single channel of seismic records, 1≤m≤M; p n,m is the virtual control point P n The sample point amplitude value of the synthetic seismic trace corresponding to the sampling point m; a,b,m 、c a,b+1,m 、c a+1,b+1,m 、c a,b+1,m are respectively the sample point amplitude values ​​of each actual reference seismic trace corresponding to the sampling point m.

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