A method and device for calibrating depth of well logging curves based on activity and variance transformation

Abstract

The present disclosure relates to a method and device for calibrating the depth of a well logging curve based on activity and variance transformation, which includes the following steps: obtaining a well logging curve and performing sampling interval uniformization processing on the well logging curve; obtaining an activity curve of a natural gamma ray curve and selecting a calibration well section on the activity curve; selecting a comparison well section on the gamma curve of a pre-cased open hole well; sliding the calibration well section on the comparison well section by a first predetermined length and calculating the Euclidean distance of the overlapping parts of the two; selecting the minimum Euclidean distance among all Euclidean distances to obtain the optimal calibration depth value of the curve; and calibrating the isotope tracer curve and the well temperature curve using the reference magnetic positioning curve. This method solves the problem that in the past, when calibrating the depth of a curve, it was necessary to manually find the peak position of the gamma curve by the naked eye and compare it with the gamma curve of the pre-cased open hole well to determine the calibration depth. The curve was manually calibrated, relying on the calibration personnel's own experience, and was greatly affected by human factors, making it difficult to ensure consistency and standardization of the calibration results.

Description

Technical Field

[0001] The present disclosure relates to the technical field of well logging curve correction, and in particular to a well logging curve depth correction method and device based on activity and variance transformation. Background Art

[0002] During production logging, various factors, including cable tension, geological conditions, instrument performance, and manual operation, can cause errors between logged depth and actual depth, impacting the accuracy of log interpretation. Log depth calibration can reduce or eliminate the impact of these errors, providing accurate logging results for oil and gas field development. Log depth calibration is essential for production logging interpretation and evaluation. Traditionally, production logging can be calibrated using gamma curves or magnetic positioning curves. Over the years, log depth calibration has evolved from manual measurement and calculation of depth errors using a steel ruler to manual computer-based calibration. This has significantly improved calibration accuracy and efficiency. However, computer-assisted manual calibration still requires interpreters to compare the peak position of the natural gamma curve in the actual logging with the peak position of the gamma curve in pre-casing openhole logging to determine the calibration depth, and manually operate the logging interpretation software to perform the calibration. Magnetic positioning curve calibration also requires manual calibration based on the depth and position of tools, such as couplings, between the actual logging curve and the reference curve, and manually operate the logging interpretation software to perform the calibration. It can be seen that the current computer-assisted manual curve depth calibration method has complex operating procedures, deviations when the interpreter manually clicks the extreme value position of the curve amplitude using the mouse, and the depth calibration results are greatly affected by human factors. It is difficult to ensure the consistency and standardization of the depth calibration results.

[0003] Traditional depth calibration methods rely on visually identifying curve peaks or locations with dramatic morphological changes as depth comparison intervals between the two curves. Aligning the comparison curve with the reference curve inevitably results in errors in visually determining the calibration position and depth. A calibration method is needed to replace manual identification of calibration comparison locations and address the issue of depth calibration relying on the interpreter's experience, which can lead to individual differences in calibration results. Summary of the Invention

[0004] The present disclosure proposes a method and device technical solution for logging curve depth calibration based on activity and variance transformation, so as to solve the problem that in the past, when calibrating the curve depth, it was necessary to manually find the peak position of the gamma curve by the naked eye and compare it with the gamma curve of the open hole well before casing to determine the calibration depth. The curve was manually calibrated, relying on the experience of the calibration personnel themselves, and was greatly affected by human factors, making it difficult to ensure the consistency and standardization of the calibration results.

[0005] According to one aspect of the present disclosure, a method for calibrating well logging curve depth based on activity and variance transformation is provided, comprising the steps of:

[0006] Obtaining a pre-casing open hole well gamma curve, a natural gamma ray background curve, an isotope tracer curve, and a well temperature curve, and performing sampling interval unification processing on the pre-casing open hole well gamma curve and the natural gamma ray background curve;

[0007] Obtaining an activity curve containing a natural gamma ray curve in the natural gamma ray background curve, and taking the first predetermined depths above and below the predetermined number of depth positions with the maximum activity on the activity curve as the calibration depth well section;

[0008] The second predetermined depths above and below the depth position corresponding to the predetermined number of depth positions with the maximum activity on the pre-casing open hole well gamma curve are used as comparison well sections;

[0009] Slide the depth calibration section on the comparison section by a first predetermined length, and calculate the Euclidean distance of the overlapping parts of the two sections each time a sampling interval is slid;

[0010] Select the minimum Euclidean distance among all Euclidean distances, and subtract the minimum depth value of the calibration depth section from the minimum depth value of the comparison well section corresponding to the minimum Euclidean distance to obtain the calibration depth value of the curve;

[0011] Calculate the curve calibration depth value corresponding to each calibration well section respectively, select the optimal calibration depth value among all the curve calibration depth values, and calibrate the depth of all curves included in the natural gamma ray background curve using the optimal calibration depth value;

[0012] The magnetic positioning curve contained in the natural gamma ray background curve after depth calibration is selected as the reference magnetic positioning curve, and the isotope tracing curve and the well temperature curve are calibrated by variance transformation using the reference magnetic positioning curve.

[0013] Preferably, the sampling spacing uniformity processing of the pre-casing open hole gamma curve and the natural gamma background curve includes:

[0014] The pre-casing open hole gamma ray curve is compared with the natural gamma ray background curve. The curve with the relatively smaller sampling interval is taken as the standard, and the curve with the relatively larger sampling interval is resampled to make the sampling intervals of the two curves consistent.

[0015] Preferably, the method of sliding the depth calibration section on the comparison section by a first predetermined length and calculating the Euclidean distance of the overlapping portions of the two sections each time a sampling interval is slid comprises:

[0016] Aligning the minimum depth position of the calibration well section with the minimum depth position of the comparison well section;

[0017] After the positions are aligned, the Euclidean distance of the overlapping part of the calibration well section and the comparison well section is calculated. Then, every time the calibration well section slides down one sampling interval, the Euclidean distance of the overlapping part of the pre-casing open hole gamma curve and the comparison well section is calculated until the maximum depth position of the calibration well section is aligned with the maximum depth position of the comparison well section.

[0018] Preferably, the method of selecting the optimal calibration depth value from all curve calibration depth values ​​includes:

[0019] Use the curve depth correction value to calibrate the natural gamma curve to obtain the depth-corrected curve;

[0020] Calculate the standard deviation of the difference curve between the overlapping part of each depth-calibrated curve and the gamma-ray curve of the open-hole well before casing;

[0021] The curve calibration depth value corresponding to the minimum standard deviation among all standard deviations is the optimal calibration depth value.

[0022] Preferably, the method of calibrating the isotope tracer curve and the well temperature curve by variance transformation using the reference magnetic positioning curve includes:

[0023] The magnetic positioning curve included in the isotope tracing curve and the well temperature curve is used as a comparative depth calibration magnetic positioning curve, and the reference magnetic positioning curve and the comparative depth calibration magnetic positioning curve are normalized;

[0024] The standardized reference magnetic positioning curve and the comparison depth calibration magnetic positioning curve are calculated with a standard deviation every second predetermined number of sampling points to obtain a standard deviation curve of the reference magnetic positioning curve, which is the reference curve, and a standard deviation curve of the comparison depth calibration magnetic positioning curve, which is the comparison curve;

[0025] Subtracting predetermined depths from the minimum depth and the maximum depth of the comparison curve respectively, and calculating the Pearson correlation coefficient between the comparison curve and the reference curve each time the comparison curve after subtracting the predetermined depth slides downward by one sampling interval, until the comparison curve slides downward by a second predetermined length;

[0026] The maximum coefficient among all Pearson correlation coefficients is selected, and the distance that the comparison curve slides downward corresponding to the maximum coefficient is the final correction value;

[0027] All curves included in the isotope tracing curve are corrected using the final correction value obtained from the magnetic positioning curve of the isotope tracing curve, and all curves included in the well temperature curve are corrected using the final correction value obtained from the magnetic positioning curve of the well temperature curve.

[0028] According to one aspect of the present disclosure, a well logging curve depth calibration device based on activity and variance transformation is provided, including the well logging curve depth calibration method based on activity and variance transformation as described above, comprising:

[0029] An acquisition unit is used to obtain the pre-casing open hole gamma curve, natural gamma background curve, isotope tracer curve and well temperature curve;

[0030] The depth calibration unit is used to obtain the activity curve of the natural gamma ray background curve containing the natural gamma ray curve, and use the first predetermined depths above and below the predetermined number of depth positions with the maximum activity on the activity curve as the depth calibration section; use the second predetermined depths above and below the depth position corresponding to the predetermined number of depth positions with the maximum activity on the pre-casing open hole gamma curve as the comparison section; slide the depth calibration section on the comparison section by a first predetermined length, and calculate the Euclidean distance of the overlapping parts of the two each time a sampling interval is slid; select the minimum Euclidean distance among all Euclidean distances, The minimum depth value of the comparison well section corresponding to the minimum Euclidean distance is subtracted from the minimum depth value of the calibration well section to obtain the curve calibration depth value; the curve calibration depth value corresponding to each calibration well section is calculated respectively, the optimal calibration depth value among all the curve calibration depth values ​​is selected, and all curves included in the natural gamma ray background curve are calibrated using the optimal calibration depth value; and the magnetic positioning curve included in the calibrated natural gamma ray background curve is selected as the reference magnetic positioning curve; the isotope tracing curve and the well temperature curve are calibrated using the reference magnetic positioning curve.

[0031] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

[0032] Further features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings herein are incorporated into and constitute a part of the specification. These drawings illustrate embodiments consistent with the present disclosure and, together with the specification, are used to explain the technical solutions of the present disclosure.

[0034] Figure 1 A flow chart of a method for calibrating well logging curve depth based on activity and variance transformation according to an embodiment of the present disclosure is shown.

[0035] Figure 2 The natural gamma curve (GRA) and its corresponding activity curve (GRAHD) according to an embodiment of the present disclosure are shown.

[0036] Figure 3 A comparison diagram of the natural gamma ray curve (GRA) before and after depth calibration and the gamma ray curve (GR) of the open hole before casing according to an embodiment of the present disclosure is shown.

[0037] Figure 4 The reference magnetic positioning curve (GRACCL) and the well temperature magnetic positioning curve (JWCCL) and their standard deviation curves (STDGRACCL, STDJWCCL) according to an embodiment of the present disclosure are shown.

[0038] Figure 5 A comparison diagram of the well temperature magnetic positioning curve (JWCCL) after depth calibration and the reference magnetic positioning curve (GRACCL) according to an embodiment of the present disclosure is shown.

[0039] Figure 6 The overall depth-calibrated curves of the natural gamma ray curve (GRA), the reference magnetic positioning curve (GRACCL) and the well temperature magnetic positioning curve (JWCCL) in the embodiment of the present disclosure are shown. DETAILED DESCRIPTION

[0040] Various exemplary embodiments, features, and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0041] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0042] The term "and / or" herein simply describes an association relationship between associated objects, indicating that three relationships can exist. For example, "A and / or B" can represent the existence of three situations: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" herein refers to any combination of at least two of any one or more of a plurality of items. For example, "at least one of A, B, and C" can represent any one or more elements selected from the set consisting of A, B, and C.

[0043] In addition, numerous specific details are provided in the following detailed description to better illustrate the present disclosure. Those skilled in the art will appreciate that the present disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art are not described in detail in order to highlight the main points of the present disclosure.

[0044] Figure 1 The flowchart of a method for calibrating the depth of a well logging curve based on activity and variance transformation according to an embodiment of the present disclosure is shown. Figure 1As shown, a logging curve depth calibration method based on activity and variance transformation includes the following steps: Step 1: obtaining a gamma curve, a natural gamma background curve, an isotope tracer curve and a well temperature curve of a pre-cased open hole well, and performing sampling interval consistency processing on the gamma curve of the pre-cased open hole well and the natural gamma background curve; Step 2: obtaining an activity curve containing a natural gamma curve in the natural gamma background curve, and taking the first predetermined depths above and below the depth positions of the predetermined number of depth positions with the maximum activity on the activity curve as the calibration well section; Step 3: taking the second predetermined depths above and below the depth positions corresponding to the predetermined number of depth positions with the maximum activity on the gamma curve of the pre-cased open hole well as the comparison well section; Step 4: sliding the calibration well section with a first predetermined length. Well section, each time a sampling interval is slid, the Euclidean distance of the overlapping parts of the two is calculated; Step 5: Select the minimum Euclidean distance among all Euclidean distances, and subtract the minimum depth value of the calibration well section from the minimum depth value of the comparison well section corresponding to the minimum Euclidean distance to obtain the curve calibration depth value; Step 6: Calculate the curve calibration depth value corresponding to each calibration well section respectively, select the optimal calibration depth value among all curve calibration depth values, and calibrate all curves contained in the natural gamma ray background curve by the optimal calibration depth value; Step 7: Select the magnetic positioning curve contained in the calibrated natural gamma ray background curve as the reference magnetic positioning curve, and use the reference magnetic positioning curve to calibrate the isotope tracer curve and the well temperature curve through variance transformation. This solves the problems of complex operation process of production logging curve calibration, low calibration efficiency and poor consistency of calibration results. The calibration method of the present invention can realize batch calibration processing of multiple well logging curves, reduce curve calibration time, and improve the quality and work efficiency of curve calibration.

[0045] The pre-casing openhole gamma ray curve (GR) is the log obtained before casing is run. The natural gamma ray background curve, isotope tracer curve, and well temperature curve are logs obtained after casing is run. The pre-casing openhole gamma ray curve is the baseline curve for depth correction of the post-casing logging curve and is downloaded from the pre-casing openhole logging curve database.

[0046] Step 1: Obtain the pre-casing openhole gamma curve, natural gamma ray background curve, isotope tracer curve, and well temperature curve, and perform sampling spacing consistency processing on the pre-casing openhole gamma curve and natural gamma ray background curve.

[0047] In the present invention, the sampling interval unification processing of the pre-casing open hole gamma curve and the natural gamma background curve includes: comparing the pre-casing open hole gamma curve with the natural gamma background curve, taking the relatively smaller sampling interval as the standard, and resampling the curve with the relatively larger sampling interval to make the sampling intervals of the two consistent.

[0048] In an embodiment of the present invention, before performing sampling interval uniformization processing, it is necessary to check and correct all acquired curve formats, flip the reversed curves, delete the first abnormal value section of the curve, and ensure that the curve meets the depth calibration processing standard.

[0049] The natural gamma ray background curve contains a natural gamma ray curve. Therefore, the sampling intervals of the natural gamma ray (GRA) curve or the pre-casing openhole gamma ray (GR) curve need to be unified. The curve with the larger sampling interval should be resampled at a smaller sampling interval to ensure consistency between the two. For example, if the sampling interval of the natural gamma ray curve is 0.025m, and the sampling interval of the pre-casing openhole gamma ray curve is 0.05m, then the pre-casing openhole gamma ray curve should be resampled at a sampling interval of 0.025m.

[0050] Step 2: Obtain the activity curve containing the natural gamma ray curve in the natural gamma ray background curve, and use the first predetermined depths above and below the predetermined number of depth positions with the maximum activity on the activity curve as the calibration depth section.

[0051] In the embodiment of the present invention, the activity curve (GRAHD) is obtained by the existing method. The position with the maximum activity on the activity curve is the peak position of the curve. By obtaining the activity curve, the mutation section of the natural gamma curve is magnified, which is convenient for the subsequent selection of the depth calibration section. The natural gamma curve (GRA) and its corresponding activity curve (GRAHD) are as follows: Figure 2 shown.

[0052] In this embodiment of the present invention, the predetermined number is 15, and the first predetermined depth is 5 meters. After obtaining the activity curve (GRAHD), the first 15 depth positions with the highest activity on the activity curve are selected. The 5 meters above and below each depth position are used as the calibration depth section A. For example, if the maximum depth position on the activity curve is 100 meters, the 5 meters above and below the 100-meter depth, that is, 95 to 105 meters, are used as the calibration depth section. These 15 depth positions correspond to 15 calibration depth sections.

[0053] Step 3: taking the second predetermined depths above and below the depth positions corresponding to the predetermined number of depth positions with the maximum activity on the pre-casing open hole well gamma curve as comparison well sections.

[0054] In this embodiment of the present invention, the second predetermined depth is 10 meters. On the pre-casing openhole gamma curve, the 10 meters above and below the 100-meter depth position on the activity curve are used as the calibration depth section B. That is, on the pre-casing openhole gamma curve, the 10 meters above and below the 100-meter depth position, i.e., 90 to 110 meters, are used as the comparison section. Fifteen calibration depth sections correspond to 15 comparison sections.

[0055] The reason for choosing a 10-meter calibration depth section and a 20-meter comparison section is that, by default, the depth error between the natural gamma ray curve and the pre-casing openhole gamma ray curve during actual logging (logging after casing) should not exceed 15 meters. Therefore, making the comparison section longer and the calibration depth section shorter allows the calibration depth section to slide across the comparison curve, thereby finding the depth correction value with the smallest error. The section length can be adjusted based on actual conditions. Currently, 10-meter and 20-meter calibration depths are selected for high accuracy and meet the requirements.

[0056] Step 4: On the comparison well section, slide the depth calibration well section by a first predetermined length, and calculate the Euclidean distance of the overlapping parts of the two sections each time a sampling interval is slid.

[0057] In the present invention, the method of sliding the depth calibration section on the comparison well section by a first predetermined length and calculating the Euclidean distance of the overlapping parts of the two each time a sampling interval is slid includes: aligning the minimum depth position of the depth calibration section with the minimum depth position of the comparison well section; after the positions are aligned, calculating the Euclidean distance of the overlapping parts of the depth calibration section and the comparison well section, and then calculating the Euclidean distance of the overlapping parts of the pre-casing open hole gamma curve and the comparison well section each time the depth calibration section slides downward by a sampling interval, until the maximum depth position of the depth calibration section is aligned with the maximum depth position of the comparison well section.

[0058] In an embodiment of the present invention, the first predetermined length is from the minimum depth position of the comparison well section to the maximum depth position of the comparison well section. First, the minimum depth position of the calibration well section, i.e., the 95-meter depth position, is aligned with the minimum depth position of the comparison well section, i.e., the 95-meter depth position. The overlapping portion between the two is calculated, i.e., the Euclidean distance between the 90-100-meter depth position in the comparison well section and the 95-105-meter depth position in the calibration well section. The calibration well section is then slid downward by one sampling interval, i.e., 0.025 meters, and the Euclidean distance between the two is calculated, i.e., the Euclidean distance between the 90.025-100.025-meter depth position in the comparison well section and the 95-105-meter depth position in the calibration well section. This Euclidean distance is calculated again for each downward sliding sampling interval. When the maximum depth position of the calibration well section overlaps with the maximum depth position of the comparison well section, the Euclidean distance calculation between the 100-110-meter depth position in the comparison well section and the 95-105-meter depth position in the calibration well section is concluded. A total of 400 sampling points were slid down in the calibration well section, thus obtaining 400 Euclidean distances.

[0059] Among them, the Euclidean distance calculation formula is:

[0060] Where: d is the Euclidean distance; x i is the amplitude value at depth i of the comparison well section; y i is the amplitude value at depth i in the calibration well section, and N is the number of sampling points in the curve comparison well section.

[0061] Step 5: Select the minimum Euclidean distance among all Euclidean distances, and subtract the minimum depth value of the calibration well section from the minimum depth value of the comparison well section corresponding to the minimum Euclidean distance to obtain the curve calibration depth value.

[0062] In this embodiment of the present invention, the minimum value among the 400 Euclidean distances is selected. The minimum depth of the comparison well section corresponding to the minimum Euclidean distance is subtracted from the minimum depth of the calibration well section to obtain the curve calibration depth value. For example, if the comparison well section corresponding to the minimum Euclidean distance is 96.5 meters to 106.5 meters deep, the calibration well section 95 meters is subtracted from the minimum depth of the comparison well section 96.5 meters to obtain the curve calibration depth value of 1.5 meters.

[0063] According to the above process, the minimum Euclidean distance between the calibration depth section and the corresponding comparison section corresponding to the 15 depth positions with the maximum activity on the activity curve is calculated respectively, and finally 15 curve calibration depth values ​​corresponding to the 15 depth positions are obtained.

[0064] Step 6: Calculate the curve calibration depth value corresponding to each calibration well section respectively, select the optimal calibration depth value among all the curve calibration depth values, and calibrate the depth of all curves included in the natural gamma ray background curve using the optimal calibration depth value.

[0065] In the present invention, the method for selecting the optimal calibration depth value among all curve calibration values ​​includes: using the curve calibration depth value to calibrate the natural gamma curve to obtain a calibrated curve; calculating the standard deviation of the difference curve of the overlapping part of each calibrated curve and the pre-casing open hole gamma curve; the curve calibration depth value corresponding to the minimum standard deviation among all standard deviations is the optimal calibration depth value.

[0066] In this embodiment of the present invention, depth calibration is performed at 15 depth locations with maximum activity on the activity curve. A calibration value is obtained for each depth location. Each calibration value is added to the natural gamma curve to generate a calibrated depth curve, resulting in 15 calibrated depth curves. These 15 calibrated depth curves represent the results of calibrating the curve using 15 local feature segments.

[0067] In order to determine which depth-calibrated curve is the best, the standard deviation group is introduced as an evaluation criterion. This criterion can effectively evaluate the overall difference between the 15 depth-calibrated curves and the gamma curves of the open-hole wells before casing. That is, the standard deviation of the difference curve between each depth-calibrated curve and the gamma curve of the open-hole wells before casing is calculated. The curve calibration value corresponding to the minimum standard deviation is the optimal calibration value. By calibrating all the curves included in the natural gamma ray background curve using the optimal calibration value, the calibration of the natural gamma ray background curve is completed. Comparison of the natural gamma curve (GRA) before and after calibration and the gamma curve (GR) of the open-hole wells before casing Figure 3 shown.

[0068] The difference curve is the curve obtained by subtracting the value at the same depth position on the depth-calibrated curve from the gamma curve of the open hole before casing.

[0069] The standard deviation calculation formula is:

[0070] Where: N is the number of sampling points in the comparison well section; x i is the amplitude of the difference curve at depth i; μ is the average amplitude of the difference curve in the comparison section.

[0071] Step 7: Select the magnetic positioning curve contained in the natural gamma ray background curve after depth calibration as the reference magnetic positioning curve, and use the reference magnetic positioning curve to calibrate the isotope tracer curve and the well temperature curve through variance transformation.

[0072] In the present invention, the method for calibrating the depth of the isotope tracing curve and the well temperature curve by using the reference magnetic positioning curve and variance transformation includes: step 11: using the magnetic positioning curve contained in the isotope tracing curve and the well temperature curve as a comparative depth calibration magnetic positioning curve, and standardizing the reference magnetic positioning curve and the comparative depth calibration magnetic positioning curve; step 12: calculating a standard deviation of the standardized reference magnetic positioning curve and the comparative depth calibration magnetic positioning curve every second predetermined number of sampling points to obtain a standard deviation curve of the reference magnetic positioning curve, which is the reference curve, and a standard deviation curve of the comparative depth calibration magnetic positioning curve, which is the comparative curve; step 13: using the comparative curve The minimum depth and maximum depth of the line are respectively subtracted from the predetermined depth, and the Pearson correlation coefficient between the comparison curve and the baseline curve after the predetermined depth is subtracted is calculated each time the comparison curve and the baseline curve slide downward by one sampling interval until the comparison curve slides downward by a second predetermined length; Step 14: Select the maximum coefficient among all Pearson correlation coefficients, and the distance that the comparison curve corresponding to the maximum coefficient slides downward is the final correction value; Step 15: Correct all curves included in the isotope tracer curve by the final correction value obtained by the magnetic positioning curve of the isotope tracer curve, and correct all curves included in the well temperature curve by the final correction value obtained by the magnetic positioning curve of the well temperature curve.

[0073] In an embodiment of the present invention, the correction of the natural gamma background curve can be performed by comparing the natural gamma curve contained therein with the pre-casing open hole gamma curve. In the case where the isotope tracer curve and the well temperature curve do not have a natural gamma curve, correction needs to be performed using the magnetic positioning curve (CCL) contained therein. The natural gamma background curve contains a magnetic positioning curve. After the natural gamma background curve is corrected using the above method, the magnetic positioning curve contained therein is also corrected. The magnetic positioning curve of the corrected natural gamma background curve is used as the reference magnetic positioning curve (GRACCL). The reference magnetic positioning curve is used to correct the magnetic positioning curves contained in the isotope tracer curve and the well temperature curve, respectively, to obtain their respective final correction values.

[0074] Step 11: Use the isotope tracing curve and the magnetic positioning curve included in the well temperature curve as a comparative depth calibration magnetic positioning curve, and standardize the reference magnetic positioning curve and the comparative depth calibration magnetic positioning curve.

[0075] In an embodiment of the present invention, the correction method of the isotope tracer curve and the well temperature curve is the same. The magnetic positioning curve (GRBCCL) contained in the isotope tracer curve and the magnetic positioning curve (JWCCL) contained in the well temperature curve are respectively used as comparative depth calibration magnetic positioning curves. The reference magnetic positioning curve and the comparative depth calibration magnetic positioning curve are standardized so that curves of different units can be uniformly compared and processed. The standardization method used here is standard deviation standardization, also called Z-score standardization.

[0076] Among them, the standardized formula is:

[0077] For the sequence x1, x2, ..., x n Perform the transformation:

[0078] here

[0079] Then the new sequence y1, y2, ..., y n has a mean of 0 and a variance of 1 and is dimensionless.

[0080] Where: is the mean of the amplitude values ​​of all sampling points; s is the variance of all sampling points; n is the number of sampling points; y i is the standardized value.

[0081] Step 12: Calculate a standard deviation of the standardized reference magnetic positioning curve and the comparison depth magnetic positioning curve every second predetermined number of sampling points to obtain the standard deviation curve of the reference magnetic positioning curve, which is the reference curve, and the standard deviation curve of the comparison depth magnetic positioning curve, which is the comparison curve.

[0082] In an embodiment of the present invention, the second predetermined number is: 120; the standardized reference magnetic positioning curve and the comparative calibration magnetic positioning curve calculate a standard deviation for every 120 sampling points, that is, a standard deviation is calculated every 3 meters to obtain the standard deviation curve of the reference magnetic positioning curve, that is, the reference curve (STDJWCCL), and the standard deviation curve of the comparative calibration magnetic positioning curve, that is, the comparison curve (STDGRACCL).

[0083] The reference magnetic positioning curve (GRACCL) and the well temperature magnetic positioning curve (JWCCL) and their standard deviation curves (STDGRACCL, STDJWCCL) are as follows: Figure 4 shown.

[0084] Step 13: Subtract a predetermined depth from the minimum depth and the maximum depth of the comparison curve respectively, and calculate the Pearson correlation coefficient between the comparison curve and the reference curve each time the comparison curve after subtracting the predetermined depth slides down one sampling interval until the comparison curve slides down a second predetermined length.

[0085] In the embodiment of the present invention, the error between the comparison curve and the reference curve is assumed to be no greater than 10 meters, so the predetermined depth is 10 meters. If the depths of the comparison curve and the reference curve are between 0 and 100 meters, then after subtracting the predetermined depth of 10 meters from the comparison curve, the depth of the comparison curve is between -10 and 90 meters.

[0086] Calculate the Pearson correlation coefficient of the common part between the depth of 0-100 meters of the baseline curve and the depth of -10-90 meters of the comparison curve, that is, the common part is the depth of 0-90 meters. Then calculate the Pearson correlation coefficient of the comparison curve and the baseline curve every time they slide down one sampling interval. That is, the depth of the comparison curve after sliding down one sampling interval is -9.975 to 90.025 meters, and the depth of the baseline curve after sliding down one sampling interval is 0.025 to 100.025 meters. Calculate the Pearson correlation coefficient between the two.

[0087] The calculation is stopped when the comparison curve slides down a second predetermined length, wherein the second predetermined length is 20 meters, that is, the calculation is stopped when the comparison curve slides down from -10 meters to 90 meters to 10 meters to 110 meters.

[0088] Step 14: Select the maximum coefficient among all Pearson correlation coefficients. The distance that the comparison curve slides downward corresponding to the maximum coefficient is the final correction value.

[0089] In the embodiment of the present invention, a Pearson correlation coefficient is calculated every time a sampling interval is slid down, and the sliding distance of the comparison curve corresponding to the largest Pearson correlation coefficient is the final correction value. For example, the magnetic positioning curve of the isotope logging curve, that is, the comparison curve, has the largest Pearson correlation coefficient with the reference curve when the curve slides down to a depth of 2.5 meters to 102.5 meters. The sliding distance of the comparison curve from the minimum depth of -10 meters to 2.5 meters is 12.5 meters, and the final correction value is 12.5 meters.

[0090] Step 15: Correct all curves included in the isotope tracing curve using the final correction value obtained from the magnetic positioning curve of the isotope tracing curve, and correct all curves included in the well temperature curve using the final correction value obtained from the magnetic positioning curve of the well temperature curve.

[0091] In the embodiment of the present invention, all the logging curves included in the isotope logging curve are corrected by using the final correction value of the isotope logging curve. Similarly, the magnetic positioning curve of the well temperature curve, that is, the final correction value obtained by calculating the Pearson correlation coefficient between the comparison curve and the reference curve, is corrected for all the curves included in the well temperature curve, thus completing the correction of all the logging curves of the target well. The comparison of the well temperature magnetic positioning curve (JWCCL) after depth calibration and the reference magnetic positioning curve (GRACCL) is shown in Figure 2. Figure 5 shown.

[0092] The overall depth calibration curves of the natural gamma ray curve (GRA), the reference magnetic positioning curve (GRACCL) and the well temperature magnetic positioning curve (JWCCL) are as follows: Figure 6 shown.

[0093] The present invention has a reliable principle, a reasonable design, a convenient method, and effectively reduces labor costs. The method of the present invention is used to perform depth calibration on logging curves, and is suitable for promotion and application in production logging projects that measure natural gamma and magnetic positioning curves. The present invention selects depth comparison sections using activity calculation and variance transformation to amplify the location of curve mutations. Compared with manual selection of depth correction positions, the depth comparison sections of the located curves are more accurate, improving the quality and accuracy of curve depth calibration and ensuring that all curves required for the final logging interpretation are at the same depth.

[0094] The execution subject of the well logging curve depth calibration method based on activity and variance transformation may be an information processing device. For example, the well logging curve depth calibration method based on activity and variance transformation may be executed by a terminal device, a server, or other processing device, wherein the terminal device may be a user equipment (UE), a mobile device, a user terminal, a terminal, a cellular phone, a cordless phone, a personal digital assistant (PDA), a handheld device, a computing device, an in-vehicle device, a wearable device, etc. In some possible implementations, the well logging curve depth calibration method based on activity and variance transformation may be implemented by a processor calling computer-readable instructions stored in a memory.

[0095] The present invention also proposes a logging curve depth calibration device based on activity and variance transformation, including the logging curve depth calibration method based on activity and variance transformation as described above, characterized in that it includes: an acquisition unit for acquiring a pre-cased open hole well gamma curve, a natural gamma ray background curve, an isotope tracer curve and a well temperature curve; a depth calibration unit for obtaining an activity curve containing a natural gamma curve in the natural gamma ray background curve, and taking the first predetermined depths above and below the depth positions of the predetermined number of depth positions with the maximum activity on the activity curve as the calibration depth well section; taking the second predetermined depths above and below the depth position corresponding to the predetermined number of depth positions with the maximum activity on the pre-cased open hole well gamma curve as the comparison well section; on the comparison well section, taking the first predetermined depth A fixed-length sliding depth calibration well section is used. Each time a sampling interval is slid, the Euclidean distance of the overlapping parts of the two is calculated; the minimum Euclidean distance among all Euclidean distances is selected, and the minimum depth value of the comparison well section corresponding to the minimum Euclidean distance is subtracted from the minimum depth value of the calibration well section to obtain the curve calibration depth value; the curve calibration depth value corresponding to each calibration well section is calculated respectively, and the optimal calibration depth value among all curve calibration depth values ​​is selected, and all curves included in the natural gamma ray background curve are calibrated by the optimal calibration depth value; and the magnetic positioning curve included in the calibrated natural gamma ray background curve is selected as the reference magnetic positioning curve; the isotope tracing curve and the well temperature curve are calibrated by the reference magnetic positioning curve.

[0096] In some embodiments, the functions or units and modules included in the device provided by the embodiments of the present disclosure can be used to execute the method described in the above method embodiments. The specific implementation can refer to the description of the above method embodiments. For the sake of brevity, it will not be repeated here.

[0097] The present disclosure also provides a computer-readable storage medium having computer program instructions stored thereon, wherein the computer program instructions implement the above method when executed by a processor. The computer-readable storage medium may be a non-volatile computer-readable storage medium.

[0098] The present disclosure also provides an electronic device, comprising: a processor; a memory for storing instructions executable by the processor; wherein the processor is configured to perform the above method. The electronic device can be provided as a terminal, a server, or other device.

[0099] The open-hole gamma ray (GR) curves of all wells are stored in a database. The computer program will load multiple actual well logging data at one time, automatically extract the natural gamma ray (GRA) curves and magnetic location (CCL) curves required for depth calibration, and perform batch depth calibration on the natural gamma ray (GRA) curves obtained from actual well logging and the open-hole gamma ray (GR) and magnetic location (CCL) curves according to the above method. The program returns a comparison chart of the calibrated curves and the baseline curve, as well as the depth correction value, and returns specific anomaly information for wells with anomalies.

[0100] The present invention addresses the current challenges of complex production logging curve depth calibration procedures, low calibration efficiency, and poor calibration result consistency. By acquiring batches of logging curves using a computer and performing calibration using the aforementioned method, the present invention enables batch calibration of logging curves for multiple wells, reducing calibration time and improving calibration quality and efficiency. The entire calibration process can be performed by a preconfigured computer program, eliminating the need for manual intervention and reducing labor costs. The calibration process takes only 40-60 seconds, significantly improving efficiency.

[0101] It can be understood that the above-mentioned various method embodiments mentioned in the present disclosure can be combined with each other to form combined embodiments without violating the principle logic. Due to space limitations, the present disclosure will not elaborate on them.

[0102] Those skilled in the art will understand that in the above-mentioned method of the specific implementation method, the writing order of each step does not mean a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0103] While various embodiments of the present disclosure have been described above, the foregoing description is intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technical improvements to existing technologies, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for calibrating well logging curve depth based on activity and variance transformation, characterized in that: Including steps: Obtaining a pre-casing open hole well gamma curve, a natural gamma ray background curve, an isotope tracer curve, and a well temperature curve, and performing sampling interval unification processing on the pre-casing open hole well gamma curve and the natural gamma ray background curve; Obtaining an activity curve containing a natural gamma ray curve in the natural gamma ray background curve, and taking the first predetermined depths above and below the predetermined number of depth positions with the maximum activity on the activity curve as the calibration depth well section; The second predetermined depths above and below the depth position corresponding to the predetermined number of depth positions with the maximum activity on the pre-casing open hole well gamma curve are used as comparison well sections; Slide the depth calibration section on the comparison section by a first predetermined length, and calculate the Euclidean distance of the overlapping parts of the two sections each time a sampling interval is slid; Select the minimum Euclidean distance among all Euclidean distances, and subtract the minimum depth value of the calibration depth section from the minimum depth value of the comparison well section corresponding to the minimum Euclidean distance to obtain the calibration depth value of the curve; Calculate the curve calibration depth value corresponding to each calibration well section respectively, select the optimal calibration depth value among all the curve calibration depth values, and calibrate the depth of all curves included in the natural gamma ray background curve using the optimal calibration depth value; The magnetic positioning curve contained in the natural gamma ray background curve after depth calibration is selected as the reference magnetic positioning curve, and the isotope tracer curve and the well temperature curve are calibrated by variance transformation using the reference magnetic positioning curve. The method includes: using the magnetic positioning curve contained in the isotope tracer curve and the well temperature curve as the comparative depth calibration magnetic positioning curve, and standardizing the reference magnetic positioning curve and the comparative depth calibration magnetic positioning curve; calculating a standard deviation of the standardized reference magnetic positioning curve and the comparative depth calibration magnetic positioning curve every second predetermined number of sampling points to obtain a standard deviation curve of the reference magnetic positioning curve, namely the reference curve, and the standard deviation curve of the comparative depth calibration magnetic positioning curve. that is, the comparison curve; the minimum depth and the maximum depth of the comparison curve are respectively subtracted from the predetermined depth, and the Pearson correlation coefficient between the comparison curve and the baseline curve is calculated each time the comparison curve after subtracting the predetermined depth slides downward by one sampling interval, until the comparison curve slides downward by a second predetermined length; the maximum coefficient among all Pearson correlation coefficients is selected, and the distance that the comparison curve corresponding to the maximum coefficient slides downward is the final correction value; the final correction value obtained by the magnetic positioning curve of the isotope tracing curve is used to correct all curves included in the isotope tracing curve, and the final correction value obtained by the magnetic positioning curve of the well temperature curve is used to correct all curves included in the well temperature curve.

2. The method for calibrating well logging curve depth based on activity and variance transformation according to claim 1, characterized in that: Performing sampling spacing consistency processing on the pre-casing open hole gamma ray curve and the natural gamma ray background curve, including: The pre-casing open hole gamma ray curve is compared with the natural gamma ray background curve. The curve with the relatively smaller sampling interval is taken as the standard, and the curve with the relatively larger sampling interval is resampled to make the sampling intervals of the two curves consistent.

3. The method for calibrating well logging curve depth based on activity and variance transformation according to claim 1, characterized in that: The method of sliding the depth calibration section on the comparison well section by a first predetermined length and calculating the Euclidean distance of the overlapping parts of the two sections each time a sampling interval is slid comprises: Aligning the minimum depth position of the calibration well section with the minimum depth position of the comparison well section; After the positions are aligned, the Euclidean distance of the overlapping part of the calibration well section and the comparison well section is calculated. Then, every time the calibration well section slides down one sampling interval, the Euclidean distance of the overlapping part of the pre-casing open hole gamma curve and the comparison well section is calculated until the maximum depth position of the calibration well section is aligned with the maximum depth position of the comparison well section.

4. The method for calibrating well logging curve depth based on activity and variance transformation according to claim 1, characterized in that: The method for selecting the optimal calibration depth value from all curve calibration depth values ​​includes: Use the curve depth correction value to calibrate the natural gamma curve to obtain the depth-corrected curve; Calculate the standard deviation of the difference curve between the overlapping part of each depth-calibrated curve and the gamma-ray curve of the open-hole well before casing; The curve calibration depth value corresponding to the minimum standard deviation among all standard deviations is the optimal calibration depth value.

5. A well logging curve depth calibration device based on activity and variance transformation, comprising the well logging curve depth calibration method based on activity and variance transformation according to any one of claims 1 to 4, characterized in that: include: An acquisition unit is used to obtain the pre-casing open hole gamma curve, natural gamma background curve, isotope tracer curve and well temperature curve; The depth calibration unit is used to obtain the activity curve of the natural gamma ray background curve containing the natural gamma ray curve, and use the first predetermined depths above and below the predetermined number of depth positions with the maximum activity on the activity curve as the depth calibration section; use the second predetermined depths above and below the depth position corresponding to the predetermined number of depth positions with the maximum activity on the pre-casing open hole gamma curve as the comparison section; slide the depth calibration section on the comparison section with a first predetermined length, and calculate the Euclidean distance of the overlapping parts of the two each time a sampling interval is slid; select the minimum Euclidean distance among all the Euclidean distances and use the minimum Euclidean distance as the comparison section. The minimum depth value of the comparison well section corresponding to the small Euclidean distance is subtracted from the minimum depth value of the calibration well section to obtain the curve calibration depth value; the curve calibration depth value corresponding to each calibration well section is calculated respectively, the optimal calibration depth value among all the curve calibration depth values ​​is selected, and all curves included in the natural gamma ray background curve are calibrated by the optimal calibration depth value; and the magnetic positioning curve included in the calibrated natural gamma ray background curve is selected as the reference magnetic positioning curve; the isotope tracer curve and the well temperature curve are calibrated by the reference magnetic positioning curve, and the method comprises: The isotope tracing curve and the well temperature curve include a magnetic positioning curve as a comparison depth calibration magnetic positioning curve, and the baseline magnetic positioning curve and the comparison depth calibration magnetic positioning curve are standardized; a standard deviation is calculated for the standardized baseline magnetic positioning curve and the comparison depth calibration magnetic positioning curve every second predetermined number of sampling points to obtain a standard deviation curve of the baseline magnetic positioning curve, which is the baseline curve, and a standard deviation curve of the comparison depth calibration magnetic positioning curve, which is the comparison curve; the minimum depth and maximum depth of the comparison curve are respectively subtracted from the predetermined depth, and the Pearson correlation coefficient of the comparison curve and the baseline curve is calculated each time the comparison curve after subtracting the predetermined depth slides down one sampling interval until the comparison curve slides down a second predetermined length; the maximum coefficient of all Pearson correlation coefficients is selected, and the distance the comparison curve corresponding to the maximum coefficient slides down is the final correction value; all curves included in the isotope tracing curve are corrected by the final correction value obtained by the magnetic positioning curve of the isotope tracing curve, and all curves included in the well temperature curve are corrected by the final correction value obtained by the magnetic positioning curve of the well temperature curve.

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