A method for correcting well logging curves in inclined wells and its application

Abstract

The present invention discloses a method for correcting well logging curves of a deviated well, comprising the following steps: analyzing and interpreting seismic profiles to obtain structural interpretation data; drilling and measuring relevant geological parameters to obtain original data of the deviated well and performing analysis and comparison to obtain well point layering data; establishing a structural framework model and performing three-dimensional grid division to obtain a three-dimensional structural model; importing the well logging curves that need to be corrected into the three-dimensional structural model; uniformly interpolating under the constraints of the three-dimensional structural model; establishing an equivalent virtual vertical well, extracting parameters of the geological parameter model to the equivalent virtual vertical well, and obtaining corrected well logging curves. The present invention also discloses an application of a method for correcting well logging curves of a deviated well. The present invention realizes the description of the three-dimensional spatial distribution characteristics of the well logging data of the deviated well by means of three-dimensional modeling, and creates an equivalent virtual vertical well to sample the logging data in the three-dimensional space to the equivalent virtual vertical well, thereby realizing the correction of the well logging curves of the deviated well.

Description

Technical Field

[0001] The present invention relates to the technical field of well logging curve correction, and more particularly to a well logging curve correction method for a deviated well and application thereof. Background Art

[0002] Due to the limited reach of wellhead platforms, offshore oilfield development mostly utilizes directional wells. Some onshore oilfields, constrained by topography and geological conditions, also employ directional wells to develop oil and gas reservoirs. Furthermore, some exploratory wells with poor target formation high overlap are drilled using directional wells. However, the formation thickness encountered by deviated wells deviates from the true formation thickness due to factors such as formation dip, well inclination, and azimuth, and the degree of deviation varies in different situations. Mud logs obtained from deviated wells exhibit varying degrees of distortion compared to those from vertical wells. Directly applying deviated well logs and lithologic information for formation correlation can significantly deviate from the actual results due to the influence of well trajectories. This impacts the accuracy of interwell sand body comparisons and reservoir distribution analysis, making it inadequate for precise water injection and remaining oil prediction in oilfields. Furthermore, significant variations in apparent and vertical thicknesses from deviated wells with different trajectories make it difficult to accurately determine the true thickness of the subsurface reservoir, hindering the assessment of oil and gas field reserves and remaining development potential.

[0003] A method for correcting directional well logging data belongs to the technical field of oil and gas exploration and development. This invention fully considers the influence of formation dip. Based on the intersecting positional relationship between the directional well trajectory and the formation, it uses formation dip and directional well inclination data to correct the deviated well depth from the logging data to the virtual vertical well depth through trigonometric functions and differential thinking. This method enables comparative studies of deviated and vertical wells across the entire region under the same standard, providing important guidance for the study of sedimentary reservoir distribution in the exploration area.

[0004] However, the above scheme uses formation dip and directional well inclination data to correct the inclined well depth of the logging data to the virtual vertical well depth through trigonometric functions and differential thinking. This scheme is only applicable to situations where the formation dip is stable. In complex situations where the formation dip changes greatly and the top and bottom of the formation structure are not parallel, the correction error is large. In addition, the calculation process needs to distinguish the relationship between the drilling direction of the directional well and the formation dip, which is relatively complicated. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of existing directional well logging data correction methods, which have limited applicability, complex calculations, and large correction errors for complex stratigraphic structures. The present invention provides a method for correcting deviated well logging curves. This method uses three-dimensional modeling to describe the three-dimensional spatial distribution characteristics of deviated well logging data. It also creates an equivalent virtual vertical well to sample the logging data in three dimensions onto the equivalent virtual vertical well, thereby correcting deviated well logging curves. The method has a wide range of applicability, minimizes correction errors, and is easy to use.

[0006] The purpose of the present invention can be achieved by adopting the following technical solutions:

[0007] A method for correcting well logging curves in a deviated well comprises the following steps:

[0008] S1: Analyze and interpret the underground seismic profile at the location where drilling operations are required to obtain structural interpretation data;

[0009] S2: Conduct drilling operations and measure relevant geological parameters to obtain original data of the inclined well, including various logging curves. Analyze and compare the original data of the inclined well to obtain well point stratification data.

[0010] S3: Determine the horizontal boundary of the structural model based on the horizontal projection range of the inclined well trajectory, and perform horizontal grid division within the boundary range. Build a structural framework model describing the relationship between the inclined well trajectory and the stratum based on the structural interpretation data and well point stratification data. Then, perform vertical grid division on the structural framework model to obtain a three-dimensional structural model.

[0011] S4: importing the logging curves that need to be corrected in the original data into the 3D structural model;

[0012] S5: Under the constraints of the 3D grid of the 3D structural model, uniform interpolation is performed to obtain a geological parameter model;

[0013] S6: Determine the plane position of the equivalent virtual vertical well according to the coordinates of the intersection of the inclined well and the geological layer in the geological parameter model, establish an equivalent virtual vertical well, extract the parameters in the geological parameter model to the equivalent virtual vertical well, and obtain the corrected well logging curve.

[0014] A deviated well is a well with a certain inclination angle. Due to drilling site limitations, offshore and some onshore oil fields use directional wells with a certain inclination angle to drill underground targets. During drilling, deviated wells use rotary steering technology to drill in a specific direction until the underground target is reached. Raw data from deviated wells includes logging data such as natural gamma, resistivity, natural potential, acoustic waves, density, and neutrons obtained through geological logging, as well as logging data such as gas logging and lithology data obtained through geological logging. These various data are all functions of depth and are various logging curves. These logging curves include well logging curves and logging curves. Well logging curves are obtained through geological logging, and logging curves are obtained through geological logging. However, due to factors such as well inclination, formation dip, and azimuth, the drilled inclined well is not in the ideal shape as planned. Therefore, the various logging curves in the original data collected by inclined well drilling will usually have different degrees of deformation compared with the logging curves of vertical wells, and the degree of deformation of different wells is also different. Therefore, it is difficult to directly use the data of inclined wells to analyze the true state of underground geological bodies, which affects the evaluation of underground oil and gas reserves, development methods, development potential, etc., resulting in the inability to accurately analyze the development and utilization effects of underground oil and gas resources, and it is difficult to guide the effective development of underground oil and gas resources.

[0015] The present invention uses structural interpretation data and well point layering data to establish a structural framework model, then performs a three-dimensional grid division on the established structural framework model to obtain a three-dimensional structural model. The well logging curves that require correction are then imported into the grid of the three-dimensional structural model. After importing the well logging curves, only the grids intersecting the deviated well trajectory in the three-dimensional structural model have parameter values. To ensure that the entire three-dimensional structural model has values, or to ensure that at least the grids intersecting the three-dimensional structural model with an equivalent virtual vertical well have parameter values, the three-dimensional structural model must be uniformly interpolated within the constraints of the three-dimensional grid to obtain a geological parameter model. An equivalent virtual vertical well is established at the midpoint between the top interface of the three-dimensional structural model and the bottom interface where the deviated well enters and exits the model, representing a vertical simulated ideal well. After extracting parameters from the geological parameter model from the established equivalent virtual vertical well, the correction of the well logging curves is completed. These parameters eliminate the problem of inaccurate information such as formation thickness due to the influence of factors such as the trajectory on the deviated well depth, resulting in a more realistic correspondence between each depth and each parameter. The above process can be computer-assisted.

[0016] Furthermore, in step S1, seismic information is collected from the underground geological body to obtain a seismic profile, and the seismic profile is analyzed and interpreted to obtain structural interpretation data.

[0017] Before mining operations, a preliminary investigation of the area to be operated is required. The seismic information of the underground geological body can be collected from previous generations. If there is no data collected by previous generations, seismic information can be collected by yourself and then analyzed and interpreted.

[0018] Furthermore, in step S2, based on the regional sedimentary background, combined with the cyclic characteristics of the logging curve in the original data of the inclined well and the rhythmic characteristic information of the logging lithology, the specific depth position data of different layers on the inclined well are determined, and the well point stratification data are obtained through stratigraphic comparison analysis.

[0019] According to the depth value of the well point layer data, the corresponding inclined well trajectory data at the depth position is searched to determine the spatial position X, Y, and Z coordinates of the well point layer position.

[0020] Furthermore, in step S3, after determining the horizontal boundary of the structural model according to the horizontal projection range of the inclined well trajectory, two mutually perpendicular directions are selected within the boundary range, and appropriate intervals are respectively delineated in these two directions to perform grid division on the horizontal plane, and the structural interpretation data is corrected according to the well point stratification data, so that the structural interpretation data near the well point position matches the well point stratification data, and the top geological layer and the bottom geological layer of the geological body are obtained, and the topological relationship of the data points of the top geological layer and the bottom geological layer of the geological body after correction is analyzed to obtain a structural framework model, set the number of grids in the vertical direction for the structural framework model, and further vertically subdivide the interior of the geological body within the spatial range defined between the top geological layer and the bottom geological layer of the geological body to obtain a three-dimensional structural model.

[0021] When dividing the structural frame model into grids in the vertical direction, the value per unit corresponding to the vertical grid can be determined according to the sampling rate of the original data, and then the vertical grid is divided by setting an appropriate spacing according to the sampling rate in the vertical direction to obtain a three-dimensional grid model.

[0022] Furthermore, in step S4, the depth data of the well logging curve is matched with the depth data of the three-dimensional structural model, and the corresponding relationship between the two depths is found for matching, so that the well logging parameters represented by the well logging curve are assigned to the grid of the three-dimensional structural model, completing the import of the well logging parameters.

[0023] Since the well logging curve is a function of depth, when the well logging curve is imported into the 3D structural model, after matching the depth, the parameter value corresponding to the depth on the well logging curve can be assigned to the 3D structural model.

[0024] Furthermore, in step S6, the coordinate value of the midpoint of the two intersection points is calculated based on the X and Y coordinates of the two intersection points of the inclined well and the top and bottom surfaces of the target layer, and the X and Y values ​​of the midpoint are used as the plane position parameters of the equivalent virtual vertical well. Vertically, 0m is used as the starting point of the Z value of the equivalent virtual vertical well trajectory, and the maximum Z value of the grid at this plane position is used as the maximum Z value of the trajectory.

[0025] In this scheme, the midpoint between the inclined well and the top and bottom geological layers of the geological body is taken as the point of the equivalent virtual vertical well. The equivalent virtual vertical well is a vertical well. It is only necessary to determine the point of the equivalent virtual well on the plane where the X-axis and Y-axis are located to establish the equivalent virtual vertical well.

[0026] Furthermore, in step S6, the coordinate data on the equivalent virtual vertical well trajectory is matched with the spatial position of the geological parameter model, and the corresponding position on the equivalent virtual vertical well is assigned according to the interpolation result in the geological parameter model to obtain the well logging parameters on the equivalent virtual vertical well, thereby completing the correction of the well logging curve.

[0027] After the geological parameter model is interpolated, the intersection of the geological parameter model and the equivalent virtual vertical well trajectory has been assigned a value. At this time, according to the correspondence between the depth of the equivalent virtual vertical well and the depth of the geological parameter model, the well logging parameters corresponding to each depth of the equivalent virtual vertical well can be obtained. The functional relationship between the depth of the equivalent virtual well and the well logging parameters is the corrected well logging parameters.

[0028] An application of a method for correcting well logging curves in a deviated well includes the method for correcting well logging curves in a deviated well as described above, and further includes the following steps:

[0029] S7: Repeat steps S4-S6 for the multiple well logging curves of each deviated well to obtain multiple corrected well logging curves;

[0030] S8: Conduct fine sand body comparison between adjacent inclined wells and between inclined wells and vertical wells.

[0031] Fine sand body comparison between adjacent deviated wells, and between adjacent deviated and vertical wells, is a crucial basis for guiding fine waterflooding operations in oilfields. The results can also be used to guide remaining oil prediction. However, without correcting well logging curves, fine sand body comparison results can deviate significantly from the actual situation, affecting the accuracy of inter-well sand body comparison and reservoir distribution analysis. This leads to inconsistent evaluations of operational effectiveness, hindering accurate assessments of oil and gas resource development outcomes and making it difficult to effectively guide subsequent development of subsurface oil and gas resources.

[0032] Furthermore, in step S7, for each deviated well, at least the natural gamma curve, resistivity curve and lithology curve in the original data of the deviated well need to be corrected respectively to obtain at least three logging curves.

[0033] The most basic parameters required for sand body comparison are natural gamma curve, resistivity curve, and lithology. Other types of parameters can also be added in some cases to improve the accuracy of the comparison results.

[0034] Furthermore, in step S8, each inclined well measures the corresponding thickness of sandstone and mudstone in each section according to the corrected logging curve, and then calculates the formation thickness and depth of each layer, so as to compare adjacent inclined wells and inclined wells with vertical wells.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] Through 3D modeling, the 3D spatial distribution of deviated well logging data is described. By creating an equivalent virtual vertical well, the logging data in 3D space is sampled onto the equivalent virtual vertical well, thereby correcting the deviated well logging curve. This approach has a wide range of applications, low correction error, and is easy to use. Furthermore, the corrected logging curves can be used for detailed sand body comparison, making the comparison results closer to reality and better guiding production operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the changes in formation thickness and logging curves of inclined wells under different conditions of monocline formations in the present invention;

[0038] Figure 2 This is a schematic diagram of a stratum with varying inclination angles when a slanted well is drilled through the stratum according to the present invention;

[0039] Figure 3 Schematic diagram of the three-dimensional structural model of the present invention;

[0040] Figure 4 This is a schematic diagram of importing the natural gamma ray logging curve into a three-dimensional structural model according to the present invention;

[0041] Figure 5 A schematic diagram showing the spatial interpolation results of the natural gamma ray logging curve and the creation of an equivalent virtual vertical well according to the present invention;

[0042] Figure 6 Schematic diagram for comparison of fine sand bodies of the present invention. DETAILED DESCRIPTION

[0043] The present invention is further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only and are schematic, not actual, representations. They should not be construed as limiting this patent. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted from the drawings.

[0044] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0045] Example 1

[0046] A method for correcting well logging curves in a deviated well comprises the following steps:

[0047] S1: Analyze and interpret the underground seismic profile at the location where drilling operations are required to obtain structural interpretation data;

[0048] S2: Conduct drilling operations and measure relevant geological parameters to obtain original data of the inclined well, including various logging curves. Analyze and compare the original data of the inclined well to obtain well point stratification data.

[0049] S3: Determine the horizontal boundary of the structural model based on the horizontal projection range of the inclined well trajectory, and perform horizontal grid division within the boundary range. Build a structural framework model describing the relationship between the inclined well trajectory and the stratum based on the structural interpretation data and well point stratification data. Then, perform vertical grid division on the structural framework model to obtain a three-dimensional structural model.

[0050] S4: importing the logging curves that need to be corrected in the original data into the 3D structural model;

[0051] S5: Under the constraints of the 3D grid of the 3D structural model, uniform interpolation is performed to obtain a geological parameter model;

[0052] S6: Determine the plane position of the equivalent virtual vertical well according to the coordinates of the intersection of the inclined well and the geological layer in the geological parameter model, establish an equivalent virtual vertical well, extract the parameters in the geological parameter model to the equivalent virtual vertical well, and obtain the corrected well logging curve.

[0053] A deviated well is a well with a certain inclination angle. Due to drilling site limitations, offshore and some onshore oil fields use directional wells with a certain inclination angle to drill underground targets. During drilling, deviated wells use rotary steering technology to drill in a specific direction until the underground target is reached. Raw data from deviated wells includes logging data such as natural gamma, resistivity, natural potential, acoustic waves, density, and neutrons obtained through geological logging, as well as logging data such as gas logging and lithology data obtained through geological logging. These various data are all functions of depth and are various logging curves. These logging curves include well logging curves and logging curves. Well logging curves are obtained through geological logging, and logging curves are obtained through geological logging. However, due to factors such as well inclination, formation dip, and azimuth, the drilled inclined well is not in the ideal shape as planned. Therefore, the various logging curves in the original data collected by inclined well drilling will usually have different degrees of deformation compared with the logging curves of vertical wells, and the degree of deformation of different wells is also different. Therefore, it is difficult to directly use the data of inclined wells to analyze the true state of underground geological bodies, which affects the evaluation of underground oil and gas reserves, development methods, development potential, etc., resulting in the inability to accurately analyze the development and utilization effects of underground oil and gas resources, and it is difficult to guide the effective development of underground oil and gas resources.

[0054] The present invention uses structural interpretation data and wellpoint layering data to establish a structural framework model, then performs a three-dimensional grid division on the established structural framework model to obtain a three-dimensional structural model. The well logging curves that require correction are imported into the grid of the three-dimensional structural model. After importing the well logging curves, only the grids intersecting the deviated well trajectory in the three-dimensional structural model have parameter values. To ensure that the entire three-dimensional structural model has values, or to ensure that at least the grids intersecting the three-dimensional structural model with the equivalent virtual vertical well have parameter values, the three-dimensional structural model must be uniformly interpolated within the constraints of the three-dimensional grid to obtain a geological parameter model. The equivalent virtual vertical well is established at the midpoint between the top interface of the three-dimensional structural model and the bottom interface where the deviated well enters and exits the three-dimensional structural model, representing a vertical simulated ideal well. After extracting parameters from the geological parameter model from the established equivalent virtual vertical well, the correction of the well logging curves is completed. These parameters eliminate the problem of inaccurate information such as formation thickness caused by the influence of factors such as the trajectory on the deviated well depth, and more closely match the actual correspondence between each depth and each parameter. The above process can be computer-assisted.

[0055] Furthermore, in step S1, seismic information is collected from the underground geological body to obtain a seismic profile, and the seismic profile is analyzed and interpreted to obtain structural interpretation data.

[0056] Before mining operations, a preliminary investigation of the area to be operated is required. The seismic information of the underground geological body can be collected from previous generations. If there is no data collected by previous generations, seismic information can be collected by yourself and then analyzed and interpreted.

[0057] Furthermore, in step S2, based on the regional sedimentary background, combined with the cyclic characteristics of the logging curve in the original data of the inclined well and the rhythmic characteristic information of the logging lithology, the specific depth position data of different layers on the inclined well are determined, and the well point stratification data are obtained through stratigraphic comparison analysis.

[0058] According to the depth value of the well point layer data, the corresponding inclined well trajectory data at the depth position is searched to determine the spatial position X, Y, and Z coordinates of the well point layer position.

[0059] Furthermore, in step S3, after determining the horizontal boundary of the structural model according to the horizontal projection range of the inclined well trajectory, two mutually perpendicular directions are selected within the boundary range, and appropriate intervals are respectively delineated in these two directions to perform grid division on the horizontal plane, and the structural interpretation data is corrected according to the well point stratification data so that the structural interpretation data near the well point position matches the well point stratification data to obtain the top geological layer and the bottom geological layer of the geological body, and the topological relationship of the data points of the top geological layer and the bottom geological layer of the geological body after correction is analyzed to obtain a structural framework model, set the number of grids in the vertical direction for the structural framework model, and further vertically subdivide the interior of the geological body within the spatial range defined between the top geological layer and the bottom geological layer of the geological body to obtain a three-dimensional structural model.

[0060] In this embodiment, the specific steps of dividing the construction framework model into grids are as follows:

[0061] The boundaries for 3D gridding are determined based on the horizontal projection range of the inclined well trajectory. In this embodiment, two mutually perpendicular directions, the X-axis and the Y-axis, are selected, and horizontal gridding is performed at an appropriate grid spacing. For example, a rectangular plane boundary is defined based on the plane projection range of the inclined well trajectory and expanded outward by 200 meters. Planar grids are then created along the long and short sides of the rectangle at 10-meter intervals. The number of vertical grid divisions is estimated based on the maximum vertical spacing between the top and bottom geological layers of the geological body. The number of vertical grid divisions is equal to the maximum vertical spacing between the top and bottom surfaces (in meters) divided by the minimum vertical resolution of the well logging data (generally 0.125 meters), rounded down to the integer obtained so that the vertical grid spacing is less than or equal to the minimum vertical resolution of the well logging data. For example, if the top and bottom surface structural data at the same plane location are subtracted, the maximum vertical spacing is 60.1 meters, and the minimum vertical resolution of the well logging data is 0.125 meters, then the number of vertical grids is 481. The number of vertical grid divisions is set for the structural framework model, and the interior of the geological body is further vertically subdivided according to the determined vertical grid number within the spatial range defined between the top geological layer and the bottom geological layer of the geological body to obtain a three-dimensional structural model.

[0062] Furthermore, in step S4, the depth data of the well logging curve is matched with the depth data of the three-dimensional structural model, and the corresponding relationship between the two depths is found for matching, so that the well logging parameters represented by the well logging curve are assigned to the grid of the three-dimensional structural model, completing the import of the well logging parameters.

[0063] Since well logging curves are functions of depth, when importing well logging curves into a 3D structural model, the depths are matched and the parameter values ​​corresponding to those depths on the well logging curves can be assigned to the 3D structural model. The assignment process is as follows: Based on the spatial coordinate positions of the well trajectory and the spatial coordinate positions in the 3D structural model, the well logging curve data at different depths on the deviated well trajectory is matched to the 3D grid in the 3D structural model. An arithmetic average algorithm is then used to average the parameter values ​​at the same depth on the corresponding well logging curves in the 3D grid. This average value is used to represent the parameter value on the 3D grid at the corresponding location. The parameter values ​​on the well logging curves are then assigned to the corresponding grids in the 3D grid model, completing the import of the parameter values ​​on the well logging curves.

[0064] Furthermore, in step S6, the coordinate value of the midpoint of the two intersection points is calculated based on the X and Y coordinates of the two intersection points of the inclined well and the top and bottom surfaces of the target layer, and the X and Y values ​​of the midpoint are used as the plane position parameters of the equivalent virtual vertical well. Vertically, 0m is used as the starting point of the Z value of the equivalent virtual vertical well trajectory, and the maximum Z value of the grid at this plane position is used as the maximum Z value of the trajectory.

[0065] In this scheme, the midpoint between the inclined well and the top and bottom geological layers of the geological body is taken as the point of the equivalent virtual vertical well. The equivalent virtual vertical well is a vertical well. It is only necessary to determine the position of the equivalent virtual well on the plane where the X-axis and Y-axis are located and the maximum vertical depth of the well trajectory to establish the equivalent virtual vertical well.

[0066] Furthermore, in step S6, the coordinate data on the equivalent virtual vertical well trajectory is matched with the spatial position of the geological parameter model, and the corresponding position on the equivalent virtual vertical well is assigned according to the interpolation result in the geological parameter model to obtain the well logging parameters on the equivalent virtual vertical well, thereby completing the correction of the well logging curve.

[0067] After the geological parameter model is interpolated, the intersection of the geological parameter model and the equivalent virtual vertical well trajectory has been assigned a value. At this time, according to the correspondence between the depth of the equivalent virtual vertical well and the depth of the geological parameter model, the well logging parameters corresponding to each depth of the equivalent virtual vertical well can be obtained. The functional relationship between the depth of the equivalent virtual well and the well logging parameters is the corrected well logging parameters.

[0068] Example 2

[0069] This embodiment uses the correction method described in Example 1 to correct the natural gamma ray logging curve of the deviated well. Figure 1 This is a schematic diagram of the changes in formation thickness and logging curves of inclined wells under different conditions in monoclinal formations. It can be seen that the logging curves measured in formations under different conditions and inclined wells under different conditions will have different degrees of deviation. The present invention can correct formations and inclined wells under various conditions through modeling. Figure 2 Schematic diagram of formation with changing dip angle in order to drill through the formation with increasing inclination according to a certain dogleg degree. Figure 3 This is a schematic diagram of the three-dimensional structural model after the grid is created and divided in step S3. Figure 4 This is a schematic diagram of importing the natural gamma ray logging curve into the three-dimensional structural model in step S4. Figure 5 Create a schematic diagram for the spatial interpolation result of the natural gamma ray logging curve in step S5 and the equivalent virtual vertical well in step S6. Figure 4 and Figure 5 As shown, the interpolated geological parameter model has an expanded range of values, so that the positions passed by the trajectory in the equivalent virtual vertical well also have values.

[0070] Example 3

[0071] An application of a method for correcting well logging curves in a deviated well includes the method for correcting well logging curves in a deviated well as described in Example 1, further comprising the following steps:

[0072] S7: Repeat steps S4-S6 for the multiple well logging curves of each deviated well to obtain multiple corrected well logging curves;

[0073] S8: Conduct fine sand body comparison between adjacent inclined wells and between inclined wells and vertical wells.

[0074] Fine sand body comparisons between adjacent deviated wells, and between deviated and vertical wells, are crucial for guiding fine waterflooding operations in oilfields. These comparisons can also be used to guide remaining oil predictions. However, without correcting well logging curves, fine sand body comparisons can significantly deviate from actual results, impacting the accuracy of interwell sand body comparisons and reservoir distribution analysis, resulting in actual production outputs falling short of expectations.

[0075] In step S7, each deviated well needs to at least calibrate the natural gamma curve, resistivity curve and lithology curve in the original data of the deviated well to obtain at least three logging curves.

[0076] The most basic parameters required for sand body comparison are natural gamma curve, resistivity curve, and lithology. Other types of parameters can also be added in some cases to improve the accuracy of the comparison results.

[0077] In step S8, the thickness of sandstone and mudstone in each section of each inclined well is measured according to the corrected well logging curve, and then the formation thickness and depth of each layer are counted, so as to compare adjacent inclined wells and inclined wells with vertical wells.

[0078] like Figure 6 The figure shows a detailed sandbody comparison. After correction, the depth, position, and thickness of each sandbody in the three deviated wells have changed compared to before correction. In particular, sandbodies previously thought to be the same in the three deviated wells are now clearly distinct, such as sandbodies ③ and ⑤ in injection well A and production well B. Alternatively, sandbodies previously thought to be two disconnected, isolated sandbodies are now clearly interconnected, such as sandbody ① in production well B and injection well C. These changes in understanding before and after correction can significantly impact actual operations.

[0079] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for correcting mud logging curves in a deviated well, characterized in that: The steps include: S1: Analyze and interpret the underground seismic profile at the location where drilling operations are required to obtain structural interpretation data; S2: Conduct drilling operations and measure relevant geological parameters to obtain original data of the inclined well, including various logging curves. Analyze and compare the original data of the inclined well to obtain well point stratification data. S3: Determine the horizontal boundary of the structural model based on the horizontal projection range of the inclined well trajectory, and perform horizontal grid division within the boundary range. Build a structural framework model describing the relationship between the inclined well trajectory and the stratum based on the structural interpretation data and well point stratification data. Then, perform vertical grid division on the structural framework model to obtain a three-dimensional structural model. S4: importing the logging curves that need to be corrected in the original data into the 3D structural model; S5: Under the constraints of the 3D grid of the 3D structural model, uniform interpolation is performed to obtain a geological parameter model; S6: Determine the plane position of the equivalent virtual vertical well according to the coordinates of the intersection of the inclined well and the geological layer in the geological parameter model, establish an equivalent virtual vertical well, extract the parameters in the geological parameter model to the equivalent virtual vertical well, and obtain the corrected well logging curve.

2. The method for correcting mud logging curves in a deviated well according to claim 1, wherein: In step S1, seismic information is collected from the underground geological body to obtain a seismic profile, and the seismic profile is analyzed and interpreted to obtain structural interpretation data.

3. The method for correcting well logging curves of a deviated well according to claim 1, characterized in that: In step S2, based on the regional sedimentary background, combined with the cyclic characteristics of the logging curve in the original data of the inclined well and the rhythmic characteristics of the logging lithology, the specific depth position data of different layers in the inclined well are determined, and the well point stratification data are obtained through stratigraphic comparison analysis.

4. The method for correcting well logging curves in a deviated well according to claim 1, wherein: In step S3, after determining the horizontal boundary of the structural model according to the horizontal projection range of the inclined well trajectory, two mutually perpendicular directions are selected within the boundary range, and appropriate intervals are respectively delineated in these two directions to perform grid division on the horizontal plane, and the structural interpretation data is corrected according to the well point stratification data so that the structural interpretation data near the well point position matches the well point stratification data to obtain the top geological layer and the bottom geological layer of the geological body, and the topological relationship of the data points of the top geological layer and the bottom geological layer of the geological body after correction is analyzed to obtain a structural framework model, set the number of grids in the vertical direction for the structural framework model, and further vertically subdivide the interior of the geological body within the spatial range defined between the top geological layer and the bottom geological layer of the geological body to obtain a three-dimensional structural model.

5. The method for correcting mud logging curves in a deviated well according to claim 1, wherein: In step S4, the depth data of the well logging curve is matched with the depth data of the three-dimensional structural model, and the corresponding relationship between the two depths is found for matching, so that the well logging parameters represented by the well logging curve are assigned to the grid of the three-dimensional structural model, completing the import of the well logging parameters.

6. The method for correcting mud logging curves in a deviated well according to claim 1, wherein: In step S6, the coordinate value of the midpoint of the two intersection points is calculated based on the X and Y marks of the two intersection points of the inclined well and the top and bottom surfaces of the target layer. The X and Y values ​​of the midpoint are used as the plane position parameters of the equivalent virtual vertical well. Vertically, 0m is used as the starting point of the Z value of the equivalent virtual vertical well trajectory, and the maximum Z value of the grid at this plane position is used as the maximum Z value of the trajectory.

7. The method for correcting mud logging curves in a deviated well according to claim 6, wherein: In step S6, the coordinate data on the equivalent virtual vertical well trajectory is matched with the spatial position of the geological parameter model, and the corresponding position on the equivalent virtual vertical well is assigned a value based on the interpolation result in the geological parameter model to obtain the well logging parameters on the equivalent virtual vertical well, thereby completing the correction of the well logging curve.

8. A method for correcting mud logging curves in a deviated well, characterized in that: The method for correcting well logging curves of a deviated well according to any one of claims 1 to 7 further comprises the following steps: S7: Repeat steps S4-S6 for the multiple well logging curves of each deviated well to obtain multiple corrected well logging curves; S8: Conduct fine sand body comparison between adjacent inclined wells and between inclined wells and vertical wells.

9. The method for correcting mud logging curves in a deviated well according to claim 8, characterized in that: In step S7, each deviated well needs to at least calibrate the natural gamma curve, resistivity curve and lithology curve in the original data of the deviated well to obtain at least three logging curves.

10. The method for correcting mud logging curves in a deviated well according to claim 8, wherein: In step S8, the thickness of sandstone and mudstone in each section of each inclined well is measured according to the corrected well logging curve, and then the formation thickness and depth of each layer are counted, so as to compare adjacent inclined wells and inclined wells with vertical wells.

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