An induction logging iterative borehole correction method and apparatus
By using iterative wellbore correction methods and spline interpolation, induction logging calculations are simplified, solving the problems of excessive calculations and wellbore mud effects in existing technologies, and achieving more efficient wellbore correction results.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PETROCHINA CO LTD
- Filing Date
- 2024-11-28
- Publication Date
- 2026-05-29
Smart Images
Figure CN122106580A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of induction logging data processing technology, specifically relating to an induction logging iterative wellbore correction method and device. Background Technology
[0002] For induction logging, the apparent conductivity after skin effect correction is a combined response of wellbore mud conductivity and formation conductivity. Typically, under oil-based mud conditions, wellbore mud conductivity contributes little to the skin-corrected apparent conductivity. However, under water-based mud conditions, wellbore mud conductivity contributes significantly to the skin-corrected apparent conductivity, necessitating wellbore correction of the skin-corrected apparent conductivity value from induction logging.
[0003] The most commonly used wellbore correction method for induction logging is the adaptive wellbore correction method. This method first constructs a forward model with wellbore mud conductivity, well diameter, instrument eccentricity, and formation conductivity as independent variables and performs forward modeling. Then, based on a large number of forward modeling results, a nonlinear fast response model is established using the least squares technique. Finally, from the established nonlinear response model, the formation conductivity is solved by back-interpreting the logging response values and corresponding logging conditions (known wellbore mud conductivity, well diameter, instrument eccentricity, etc.).
[0004] The resulting formation conductivity value is considered to have undergone "adaptive" wellbore correction. As can be seen from the above steps, the formation conductivity calculated from the established model is a nonlinear calculation, which is unsuitable for inversion of induction logging data; furthermore, this wellbore correction method involves an inversion process, resulting in excessive computational steps.
[0005] Chinese Patent Publication No. CN106837299B, entitled "A System and Method for Wellbore Correction," describes a method that includes receiving array induction measurement signals and performing preliminary processing for skin effect correction to obtain skin effect corrected measurement data; performing resolution matching processing on the skin effect corrected measurement data to obtain resolution matching processed data; calculating wellbore environment data corresponding to the array based on the resolution matching processed data; and calculating wellbore corrected data based on the wellbore environment data corresponding to the array. This patent application fails to address the issue of the applicability of the wellbore correction method in induction logging data inversion. Summary of the Invention
[0006] To overcome the problems existing in the prior art, the present invention aims to provide an iterative wellbore correction method and apparatus for induction logging, which employs an iterative wellbore correction method different from existing induction logging wellbore correction methods. This method is applicable to induction logging data inversion without a reversal process, thus simplifying calculations.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides an iterative wellbore correction method for induction logging, comprising the following steps: Obtain the apparent conductivity response values of n subarrays; Calculate the first ratio of mud conductivity to formation conductivity for n subarrays under different wellbore conditions. Calculate the wellbore impact factor corresponding to the first ratio. ; For n subarrays under different well diameter conditions and wellbore influence factors The data was fitted to determine the eye influence factors of n subarrays under different well diameter conditions. The first formula of the first ratio The coefficients a, b, and c in the text; where For the formation electrical conductivity, The electrical conductivity of the wellbore mud; Given an initial apparent conductivity value of the formation The wellbore impact factor is calculated using the first formula. ; wellbore impact factors Substitute into the second formula Calculated formation apparent conductivity ,in, The apparent conductivity is the result of induction logging correction. The electrical conductivity of the wellbore mud; the apparent electrical conductivity of the formation. The wellbore influence factor is calculated by substituting it into the first formula. Then, the result is substituted into the second formula for iterative calculation to obtain the formation conductivity response value that is not affected by well mud.
[0008] Optionally, the apparent conductivity response value is the apparent conductivity response value after skin effect correction.
[0009] Optionally, the apparent conductivity response values of the n subarrays can be obtained by calculation using an instrument model or by actual instrument measurement.
[0010] Optionally, the initial apparent conductivity value of the formation Less than the conductivity of wellbore mud .
[0011] Optionally, spline interpolation can be used to calculate the required coil system and the coefficients of a, b, and c under the corresponding well diameter based on the calculated coefficients a, b, and c.
[0012] Optionally, through the definition of the wellbore impact factor Calculate the wellbore influence factor corresponding to the first ratio. ;in, The electrical conductivity of the formation outside the wellbore. For the electrical conductivity of wellbore mud, The apparent conductivity of induction logging after skin effect correction. The electrical conductivity of the formation outside the wellbore.
[0013] Secondly, the present invention provides an iterative wellbore correction system for induction logging, comprising: The data acquisition module is used to acquire the apparent conductivity response values of the n subarrays; The first calculation module is used to calculate the first ratio of mud conductivity to formation conductivity for n subarrays under different well conditions. Calculate the wellbore impact factor corresponding to the first ratio. ; The second calculation module is used to calculate the relationship between the n subarrays and the wellbore influence factor under different well diameter conditions. The data was fitted to determine the eye influence factors of n subarrays under different well diameter conditions. The first formula of the first ratio The coefficients a, b, and c in the text; where For the formation electrical conductivity, The electrical conductivity of the wellbore mud; The third calculation module is used to provide an initial apparent conductivity value for the formation. The wellbore impact factor is calculated using the first formula. ; wellbore impact factors Substitute into the second formula Calculated formation apparent conductivity ,in, The apparent conductivity is the result of induction logging correction. The electrical conductivity of the wellbore mud; the apparent electrical conductivity of the formation. The wellbore influence factor is calculated by substituting it into the first formula. Then, the result is substituted into the second formula for iterative calculation to obtain the formation conductivity response value that is not affected by well mud.
[0014] Thirdly, the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the induction logging iterative wellbore correction method.
[0015] Fourthly, the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the induction logging iterative wellbore correction method.
[0016] Fifthly, the present invention provides a computer program product including a computer-readable medium, wherein the computer-readable medium contains computer-readable program code, the program code executing the induction logging iterative wellbore correction method.
[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention provides an iterative wellbore correction method and apparatus for induction logging, proposing an iterative wellbore correction method for induction logging. This invention uses a first formula and a second formula for iterative calculation to obtain the formation conductivity response value unaffected by wellbore mud. This invention is applicable to induction logging data inversion without the need for an inversion process, simplifying calculations.
[0018] Furthermore, the present invention employs spline interpolation, which enables the interpolation of the required coil system and corresponding well diameter coefficients when the actual well diameter data lacks the corresponding well diameter data or the required coil system data. Attached Figure Description
[0019] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way.
[0020] In the attached diagram: Figure 1 The wellbore a influence factor under different well diameter conditions of the No. 3 coil of the 1515HDIL array induction logging in Embodiment 2 of the present invention. The ratio of formation conductivity to mud conductivity Relationship diagram. Figure 1a shows the wellbore influence factor for the 1515HDIL array induction logging coil No. 3 (6-inch borehole diameter). A graph showing the relationship between formation electrical conductivity and mud electrical conductivity. Figure 1 b represents the wellbore influence factor for the 1515HDIL array induction logging No. 3 coil with an 8-inch borehole diameter. The ratio of formation conductivity to mud conductivity Relationship diagram Figure 1 c represents the wellbore influence factor for the 1515HDIL array induction logging coil No. 3 with a 10-inch well diameter. The ratio of formation conductivity to mud conductivity Relationship diagram Figure 1 d represents the wellbore influence factor for the 1515HDIL array induction logging coil No. 3 with a 12-inch borehole diameter. The ratio of formation conductivity to mud conductivity Relationship diagram; Figure 2This is a cross-plot of the ratio of formation conductivity to mud conductivity of the 1515HDIL array induction logging coil No. 3 under different well diameters (6in, 8in, 10in, 12in) in Embodiment 2 of the present invention, showing the relative error between apparent conductivity after skin effect correction and true formation conductivity. Figure 3 This is a cross-plot of the ratio of formation conductivity to mud conductivity - the relative error between apparent conductivity after wellbore correction and true formation conductivity under different well diameters (6in, 8in, 10in, 12in) of the No. 3 coil of the 1515HDIL array induction logging in Embodiment 2 of the present invention. Figure 4 This is a cross-plot of the formation true conductivity and the apparent conductivity after wellbore correction under different well diameters (6in, 8in, 10in, 12in) of the No. 3 coil of the 1515HDIL array induction logging in Embodiment 2 of the present invention. Detailed Implementation
[0021] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.
[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0023] It should be noted that any reference signs placed between parentheses in the claims should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. This application can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified. The present invention will now be described in detail with reference to the accompanying drawings.
[0024] An iterative wellbore correction method for induction logging includes the following steps: Input the apparent conductivity response values of n subarrays; Calculate the first ratio of mud conductivity to formation conductivity for n subarrays under different wellbore conditions. Calculate the wellbore impact factor corresponding to the first ratio. ; For n subarrays under different well diameter conditions and wellbore influence factors The data was fitted to determine the eye influence factors of n subarrays under different well diameter conditions. The first formula of the first ratio The coefficients a, b, and c in the text; where For the formation electrical conductivity, The electrical conductivity of the wellbore mud; Given an initial apparent conductivity value of the formation The wellbore impact factor is calculated using the first formula. ; wellbore impact factors Substitute into the second formula Calculated formation apparent conductivity ,in, The apparent conductivity is the result of induction logging correction. The electrical conductivity of the wellbore mud; the apparent electrical conductivity of the formation. The wellbore influence factor is calculated by substituting it into the first formula. Then, the result is substituted into the second formula for iterative calculation to obtain the formation conductivity response value that is not affected by well mud.
[0025] The apparent conductivity response value is the apparent conductivity response value after skin effect correction.
[0026] The apparent conductivity response values of the n subarrays are obtained through instrument model calculation or actual instrument measurement.
[0027] The initial apparent conductivity value of the formation Less than the conductivity of wellbore mud .
[0028] When the actual well diameter data lacks the corresponding well diameter data or the required coil system data, interpolation is used based on the calculated coefficients a, b, and c to obtain the coefficients a, b, and c for the required coil system and the corresponding well diameter.
[0029] Based on the definition of wellbore impact factors Calculate the wellbore influence factor corresponding to the first ratio. ;in, The electrical conductivity of the formation outside the wellbore. For the electrical conductivity of wellbore mud, The apparent conductivity of induction logging after skin effect correction. The electrical conductivity of the formation outside the wellbore.
[0030] The wellbore correction method of the present invention is applicable not only to the 1515HDIL array induction logging tool, but also to other induction logging tools.
[0031] Example 1 The apparent conductivity of induction logging after skin effect correction is a combined response of the wellbore mud conductivity and the formation conductivity outside the well. Therefore, the apparent conductivity of induction logging after skin effect correction under instrument centering conditions can be expressed as:
[0032] In the formula: The apparent conductivity of induction logging after skin effect correction. For the electrical conductivity of wellbore mud, The electrical conductivity of the formation outside the wellbore. For wellbore influencing factors. It is the well diameter and the electrical conductivity of the formation outside the well. Slurry conductivity The function.
[0033] Borehole Influence Factors of a Single Induction Logging Three-Coil Subarray Under Different Borehole Conditions The ratio of formation conductivity to mud conductivity Relationship such as Figure 1 As shown.
[0034] For a given subarray, under given wellbore diameter conditions, the wellbore influence factor is... and There is a monotonically increasing relationship. Therefore, for different subarrays and under different well diameter conditions, a set of wellbore influence factors can be fitted. and The relational expression, in the form of which is: Borehole Influence Factors of Different Subarrays under Different Borehole Diameter Conditions and The coefficients a, b, and c of the relation are different.
[0035] Determining the influencing factors of different coils and wellbore diameters and After establishing the relationship, wellbore correction is performed using an iterative method to calculate the formation conductivity response excluding the influence of wellbore mud.
[0036] 1) Wellbore Influence Factors Determining the coefficients of the calculation formula Through instrument model calculations or actual instrument measurements, the electrical conductivity of different subarrays at different well diameters and mud conductivity levels was obtained. Different strata conductivity Apparent conductivity response under the condition .
[0037] Calculate the ratio of mud conductivity to formation conductivity. At the same time, according to the definition of wellbore impact factor Calculations were performed on different subarrays at different well diameters and mud conductivity. Different strata conductivity Wellbore influencing factors under certain conditions A set of one-to-one ratios of mud conductivity to formation conductivity were obtained for different subarrays under different well diameter conditions. Wellbore impact factor G data.
[0038] According to the formula The ratio of mud conductivity to formation conductivity for different subarrays under different well diameter conditions By fitting the data with the wellbore influence factor G, the wellbore influence factor of different subarrays under different well diameter conditions can be determined. and The coefficients a, b, and c of the relational expression.
[0039] 2) Iterative wellbore correction For a given subarray, the wellbore influence factor for the corresponding coil system and wellbore diameter is calculated by interpolation based on the actual wellbore diameter data. and The coefficients a, b, and c of the relation.
[0040] Given an initial apparent conductivity value of the formation According to the formula Calculate wellbore impact factors .
[0041] Optionally, .
[0042] Calculated wellbore impact factors Substitution Calculate the apparent conductivity of the formation ,Will Substitute into the formula Calculate a new wellbore impact factor Perform iterative calculations until... and The iteration stops when the error is lower than the set value. This is how the... This refers to the formation conductivity response unaffected by wellbore mud.
[0043] Example 2 In this embodiment, the input is the apparent conductivity response value of n subarrays (n=7 in this embodiment) calculated by the forward modeling of the 1515HDIL array induction logging tool, after skin effect correction, under different well diameters, different mud conductivity, and different formation conductivity conditions.
[0044] Calculate the ratio of mud conductivity to formation conductivity for n subarrays under different well conditions. At the same time, according to the definition of wellbore impact factor Calculation of mud conductivity to formation conductivity ratio One-to-one wellbore influence factors .
[0045] in, The electrical conductivity of the formation outside the wellbore. For the electrical conductivity of wellbore mud, The apparent conductivity of induction logging after skin effect correction. The electrical conductivity of the formation outside the wellbore.
[0046] According to the formula The form represents the ratio of mud conductivity to formation conductivity under different well diameter conditions for n subarrays. By fitting the wellbore impact factor G data, the wellbore impact factors of n subarrays under different well diameter conditions are determined. Ratio of mud conductivity to formation conductivity relational formula Using the coefficients a, b, and c, we obtain the model for the first formula.
[0047] Specifically, based on the actual well diameter data, if the required well diameter data or the required coil system data is missing, interpolation is used based on the calculated coefficients a, b, and c to obtain the coefficients a, b, and c for the corresponding coil system and the corresponding well diameter.
[0048] Given an initial apparent conductivity value of the formation and make According to the formula Calculate wellbore impact factors .
[0049] Calculated wellbore impact factors Substitution Calculate the apparent conductivity of the formation ,Will Substitute into the formula Calculate a new wellbore impact factor Perform iterative calculations until... and When the error meets the preset target, the iteration stops, and the formation conductivity response value unaffected by well mud is obtained.
[0050] Repeat the steps until all subarrays have been processed.
[0051] The results are as follows Figure 1 As shown, Figure 1 The horizontal axis represents the ratio of formation conductivity to mud conductivity, and the vertical axis represents the natural logarithm of the wellbore influence factor. Figure 1 It can be seen that the wellbore impact factor and There is a monotonically increasing relationship, as shown by the formula. This is used to express the relationship between the wellbore influence factor and the ratio of formation conductivity to mud conductivity.
[0052] Table 1 shows the coefficients relating the wellbore influence factor of different subarrays of the 1515HDIL array to the ratio of formation conductivity to mud conductivity under different well diameter conditions.
[0053] Table 1
[0054] Figure 2 This is a cross-plot showing the relative error between the ratio of formation conductivity to mud conductivity, skin effect corrected apparent conductivity, and formation true conductivity under different well diameters (6in, 8in, 10in, 12in) of the No. 3 coil in the 1515HDIL array induction logging. Figure 2 The horizontal axis represents the ratio of formation conductivity to mud conductivity, and the vertical axis represents the relative error between the apparent conductivity after skin effect correction and the true conductivity of the formation, calculated by the forward modeling of the 1515HDIL array induction logging instrument model.
[0055] Depend on Figure 2It can be seen that when the ratio of formation true conductivity to mud conductivity is greater than 1 (oil-based mud), the relative error of apparent conductivity after skin effect correction relative to true conductivity is less than 10%. When the ratio of formation true conductivity to mud conductivity is less than 1 (water-based mud), as the ratio of formation true conductivity to mud conductivity decreases (i.e., the ratio of formation resistivity to mud resistivity increases), the relative error of apparent conductivity after skin effect correction relative to true conductivity increases rapidly. Moreover, the larger the well diameter, the greater the relative error of apparent conductivity after skin effect correction relative to true conductivity.
[0056] Figure 3 This is a cross-plot showing the ratio of formation conductivity to mud conductivity of the 1515HDIL array induction logging coil No. 3 under different well diameters (6in, 8in, 10in, 12in) - the relative error between the apparent conductivity after wellbore correction and the true conductivity of the formation. Figure 3 The horizontal axis represents the ratio of formation conductivity to mud conductivity, and the vertical axis represents the relative error between the apparent conductivity after wellbore correction and the true formation conductivity of the 1515HDIL array induction logging coil No. 3. As shown in the figure, when the ratio of formation conductivity to mud conductivity is greater than 0.005 (i.e., the ratio of formation resistivity to mud resistivity is less than 200), the relative error between the apparent conductivity after wellbore correction and the true formation conductivity is below 10%, meeting the instrument measurement requirements.
[0057] Figure 4 This is a cross-plot of the apparent conductivity and true conductivity of the seven subarrays of the 1515HDIL array induction logging tool after tandem skin effect correction. The horizontal axis represents the formation true conductivity, and the vertical axis represents the apparent conductivity after wellbore correction. Figure 4 As can be seen, on the cross plot of apparent conductivity and true conductivity after wellbore correction, the data points all fall on the diagonal line. This indicates that for formations with conductivity less than 1 S / m, the difference between the apparent conductivity and true conductivity after wellbore correction is very small.
[0058] contrast Figure 2 and Figure 3 It can be seen that when the well diameter is less than 10 inches, the ratio of formation conductivity to mud conductivity is greater than 0.005. After wellbore correction, the relative error between apparent conductivity and true conductivity is less than 10%, which is significantly less than the relative error between apparent conductivity and true conductivity before wellbore correction.
[0059] Depend on Figure 4 As can be seen, on the cross-plot of apparent conductivity and true conductivity after wellbore correction, the data points all fall on the diagonal line. This indicates that for formations with conductivity less than 1 S / m, the difference between the wellbore-corrected apparent conductivity and the true conductivity is very small. Therefore, the relative error between the apparent conductivity and the true conductivity of the formation after correction by the induction logging iterative wellbore correction method is mostly below 10%, meeting the requirements of instrument measurement.
[0060] Example 3 Based on the iterative wellbore correction method for induction logging in Example 1, an iterative wellbore correction system for induction logging is disclosed, comprising: The data acquisition module is used to acquire the apparent conductivity response values of the n subarrays; The first calculation module is used to calculate the first ratio of mud conductivity to formation conductivity for n subarrays under different well conditions. Calculate the wellbore impact factor corresponding to the first ratio. ; The second calculation module is used to calculate the relationship between the n subarrays and the wellbore influence factor under different well diameter conditions. The data was fitted to determine the eye influence factors of n subarrays under different well diameter conditions. The first formula of the first ratio The coefficients a, b, and c in the text; where For the formation electrical conductivity, The electrical conductivity of the wellbore mud; The third calculation module is used to provide an initial apparent conductivity value for the formation. The wellbore impact factor is calculated using the first formula. ; wellbore impact factors Substitute into the second formula Calculated formation apparent conductivity ,in, The apparent conductivity is the result of induction logging correction. The electrical conductivity of the wellbore mud; the apparent electrical conductivity of the formation. The wellbore influence factor is calculated by substituting it into the first formula. Then, the result is substituted into the second formula for iterative calculation to obtain the formation conductivity response value that is not affected by well mud.
[0061] Example 4 The purpose of this embodiment is to provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the induction logging iterative wellbore correction method.
[0062] Example 5 The purpose of this embodiment is to provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the induction logging iterative wellbore correction method.
[0063] Example 6 The purpose of this embodiment is to provide a computer program product including a computer-readable medium, wherein the computer-readable medium contains computer-readable program code that executes the induction logging iterative wellbore correction method.
[0064] The steps and methods involved in the apparatuses of the above embodiments 3, 4, 5 and 6 correspond to those in embodiment 1. For specific implementation details, please refer to the relevant description section of embodiment 1.
[0065] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes. These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0066] Unless otherwise specified, the working methods or control methods involved in the above embodiments are conventional working methods or control methods in the art.
[0067] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.
Claims
1. A method for iterative wellbore correction in induction logging, characterized in that, Includes the following steps: Obtain the apparent conductivity response values of n subarrays; Calculate the first ratio of mud conductivity to formation conductivity for n subarrays under different wellbore conditions. Calculate the wellbore impact factor corresponding to the first ratio. ; For n subarrays under different well diameter conditions and wellbore influence factors The data was fitted to determine the eye influence factors of n subarrays under different well diameter conditions. The first formula of the first ratio The coefficients a, b, and c in the text; where For the formation electrical conductivity, The electrical conductivity of the wellbore mud; Given an initial apparent conductivity value of the formation The wellbore impact factor is calculated using the first formula. ; wellbore impact factors Substitute into the second formula Calculated formation apparent conductivity ,in, The apparent conductivity is the result of induction logging correction. The electrical conductivity of the wellbore mud; the apparent electrical conductivity of the formation. The wellbore influence factor is calculated by substituting it into the first formula. Then, the result is substituted into the second formula for iterative calculation to obtain the formation conductivity response value that is not affected by well mud.
2. The iterative wellbore correction method for induction logging according to claim 1, characterized in that, The apparent conductivity response value is the apparent conductivity response value after skin effect correction.
3. The iterative wellbore correction method for induction logging according to claim 1, characterized in that, The apparent conductivity response values of the n subarrays are obtained through instrument model calculation or actual instrument measurement.
4. The iterative wellbore correction method for induction logging according to claim 1, characterized in that, The initial apparent conductivity value of the formation Less than the conductivity of wellbore mud .
5. The iterative wellbore correction method for induction logging according to claim 1, characterized in that, Based on the calculated coefficients a, b, and c, spline interpolation is used to calculate the required coil system and the coefficients a, b, and c under the corresponding well diameter.
6. The iterative wellbore correction method for induction logging according to claim 1, characterized in that, Based on the definition of wellbore impact factors Calculate the wellbore influence factor corresponding to the first ratio. ;in, The electrical conductivity of the formation outside the wellbore. For the electrical conductivity of wellbore mud, The apparent conductivity of induction logging after skin effect correction. The electrical conductivity of the formation outside the wellbore.
7. An iterative wellbore correction system for induction logging, characterized in that, include: The data acquisition module is used to acquire the apparent conductivity response values of the n subarrays; The first calculation module is used to calculate the first ratio of mud conductivity to formation conductivity for n subarrays under different well conditions. Calculate the wellbore impact factor corresponding to the first ratio. ; The second calculation module is used to calculate the relationship between the n subarrays and the wellbore influence factor under different well diameter conditions. The data was fitted to determine the eye influence factors of n subarrays under different well diameter conditions. The first formula of the first ratio The coefficients a, b, and c in the text; where For the formation electrical conductivity, The electrical conductivity of the wellbore mud; The third calculation module is used to provide an initial apparent conductivity value for the formation. The wellbore impact factor is calculated using the first formula. ; wellbore impact factors Substitute into the second formula Calculated formation apparent conductivity ,in, The apparent conductivity is the result of induction logging correction. The electrical conductivity of the wellbore mud; the apparent electrical conductivity of the formation. The wellbore influence factor is calculated by substituting it into the first formula. Then, the result is substituted into the second formula for iterative calculation to obtain the formation conductivity response value that is not affected by well mud.
8. An electronic device, characterized in that, The method includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the induction logging iterative wellbore correction method according to any one of claims 1-6.
9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the induction logging iterative wellbore correction method according to any one of claims 1-6.
10. A computer program product comprising a computer-readable medium, characterized in that, The computer-readable medium contains computer-readable program code that performs the induction logging iterative wellbore correction method according to any one of claims 1-6.