Resistivity imaging method based on core surface resistivity measurement and electronic device

Abstract

This application provides a resistivity imaging method and electronic device based on core surface resistivity measurement, belonging to the field of rock electric field detection technology. The method includes: calculating the resistivity conversion value of each button electrode based on the measured voltage of each button electrode; calculating the apparent resistivity of the calibrated core sample surface based on the resistivity conversion value and the resistivity of the electrolyte; calculating the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates based on the apparent resistivity; calculating the equalized resistivity of the core sample surface based on the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates; and performing imaging processing using an imaging algorithm based on the resistivity of the core sample surface to obtain a core surface resistivity image. This application's solution can improve the accuracy of resistivity imaging.

Description

Technical Field

[0001] This application relates to the field of rock electric field detection technology, specifically to a resistivity imaging method and electronic equipment based on core surface resistivity measurement. Background Technology

[0002] Currently, in multi-scale evaluation of downhole formations, although meter-level wellbore microresistivity scanning imaging logging technology and micro-nano-level core CT (Computed Tomography) scanning technology are available, centimeter-level physical signal acquisition technology is still lacking, which limits geophysicists' understanding and assessment of reservoir details.

[0003] In existing technologies, the commonly used method is to calibrate microresistivity imaging logging using core samples drilled downhole. The entire wellbore is cylindrical, and the drilled core is also cylindrical. However, because the core casing has a certain thickness, the wellbore measured by imaging logging does not match the side of the cylindrical core. Therefore, when the lithology, porosity, or structure of the formation varies horizontally, the core cannot be used to calibrate the downhole microresistivity image.

[0004] In existing technologies, resistivity imaging has certain limitations and relatively low accuracy. Therefore, improving the accuracy of resistivity imaging remains an unsolved problem. Summary of the Invention

[0005] The purpose of this application is to provide a resistivity imaging method based on core surface resistivity measurement, which can solve the problems of the limitations and low accuracy of resistivity imaging in the prior art.

[0006] In a first aspect, embodiments of this application provide a resistivity imaging method based on core surface resistivity measurement, implemented using a core surface resistivity measuring device, the method comprising: Based on the measured voltage of each button electrode, the resistivity conversion value of each button electrode is calculated. Based on the resistivity conversion value and the resistivity of the electrolyte, the apparent resistivity of the core sample surface after calibration is calculated. Based on the apparent resistivity, the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates are calculated. The resistivity of the core sample surface after equalization was calculated based on the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates. Based on the resistivity of the core sample surface, an imaging processing algorithm is used to obtain a resistivity image of the core surface.

[0007] In one possible implementation of the first aspect, the resistivity conversion value of each button electrode is calculated based on the measured voltage of each button electrode, including: The resistivity conversion values ​​of each button electrode are calculated using the following formula:

[0008] in, This represents the converted resistivity value. l This indicates the height and position number of the button electrode on the core sample. i Indicates the number of the metal electrode plate. j This indicates the number of the button electrode on the metal plate. This represents the voltage generated on each button electrode under the influence of an alternating current signal. This represents the voltage gain value of each metal plate at each height position. This represents the voltage gain value of all metal plates at each height position.

[0009] In one possible implementation of the first aspect, the apparent resistivity of the calibrated core sample surface is calculated based on the resistivity conversion value and the resistivity of the electrolyte, including: The apparent resistivity of the calibrated core sample surface is calculated using the following formula:

[0010] in, This represents the apparent resistivity of the core sample surface. This indicates the resistivity of the electrolyte. A , B It is a constant.

[0011] In one possible implementation of the first aspect, the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates are calculated based on the apparent resistivity, including: The standard deviation of each button electrode is calculated using the following formula:

[0012] in, This indicates the standard deviation of each button electrode. Indicates the first i The first metal electrode plate j The average apparent resistivity of each button electrode at all height locations. N Indicates the number of height positions; The total standard deviation of all button electrodes on all metal plates is calculated using the following formula:

[0013] in, Q This represents the total standard deviation of all button electrodes on all metal plates. This represents the average apparent resistivity of all button electrodes on all metal plates at all height locations. Represents the first position of all height locations i The first metal electrode plate j Average apparent resistivity of each button electrode M = N × Total number of button electrodes.

[0014] In one possible implementation of the first aspect, the resistivity of the equalized core sample surface is calculated based on the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates, including: The resistivity of the homogenized core sample surface is calculated using the following formula:

[0015] in, This indicates the resistivity of the core sample surface.

[0016] In one possible implementation of the first aspect, different color levels represent different resistivity values, wherein the expression for the mapping relationship between the resistivity magnitude and the chromaticity pixels is as follows:

[0017]

[0018] in, S Indicates pixel scale factor. This represents the maximum resistivity at all coordinate locations. This represents the minimum resistivity at all coordinate locations. This represents the resistivity value measured at each coordinate position. This represents the converted pixel value.

[0019] In one possible implementation of the first aspect, the device includes: A computing device, connected to a signal acquisition device, a power module, and an electric displacement stage, is used to control the signal acquisition device and the electric displacement stage; The signal acquisition device is also connected to the electrode holder for outputting AC signals to the button electrodes and receiving AC signals output by the electrode holder. The power module is also connected to the signal acquisition equipment and the electric displacement stage, and is used to output AC voltage; Sample cell, used to hold core samples and electrolyte; Electrode holder, used for moving on core samples; The electric displacement stage is also connected to the electrode holder, which is used to control the electrode holder to move on the core sample at a preset step size.

[0020] In one possible implementation of the first aspect, the signal acquisition device includes: a signal input device and a signal output device; the signal output device is used to output an AC signal to the button electrode, and the signal input device receives the AC signal output by the electrode holder.

[0021] In one possible implementation of the first aspect, the electrolyte comprises a sodium chloride solution, and the electric displacement stage comprises a stepper motor.

[0022] In one possible implementation of the first aspect, the electrode holder includes: a coaxial annular button electrode array, a shielding electrode, an insulating rubber bushing, a retaining pin, a fixing device, a line channel, and a return electrode.

[0023] In one possible implementation of the first aspect, the electrode holder includes: a semi-circular metal plate with an inner arc surface, and an array of button electrodes arranged in the middle of the semi-circular metal plate; the upper and lower rows of button electrodes are staggered, and each button electrode is wrapped with an insulating rubber bushing.

[0024] In one possible implementation of the first aspect, the apparatus further includes a core fixing device for fixing a core sample.

[0025] Secondly, embodiments of this application provide a resistivity imaging device based on core surface resistivity measurement, the device comprising: The first calculation unit is used to calculate the resistivity conversion value of each button electrode based on the measured voltage of each button electrode. The second calculation unit is used to calculate the apparent resistivity of the core sample surface after calibration based on the resistivity conversion value and the resistivity of the electrolyte. The third calculation unit is used to calculate the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates based on the apparent resistivity. The fourth calculation unit is used to calculate the resistivity of the equalized core sample surface based on the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates. The imaging unit is used to perform imaging based on the resistivity of the core sample surface using an imaging processing algorithm to obtain a resistivity imaging map of the core surface.

[0026] Thirdly, embodiments of this application provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the resistivity imaging method based on core surface resistivity measurement as described in any of the first aspects above.

[0027] Fourthly, embodiments of this application provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the resistivity imaging method based on core surface resistivity measurement as described in any of the first aspects above.

[0028] Fifthly, embodiments of this application provide a computer program product that, when run on an electronic device, causes the electronic device to execute the resistivity imaging method based on core surface resistivity measurement as described in any of the first aspects above.

[0029] The proposed method first calculates the resistivity conversion value of each button electrode based on its voltage. Then, it calculates the apparent resistivity of the core sample surface based on the resistivity conversion value and the resistivity of the electrolyte. Next, it calculates the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates based on the apparent resistivity. Then, it calculates the resistivity of the core sample surface based on the individual standard deviations and the total standard deviations. Finally, it obtains a resistivity imaging map of the core sample surface based on the resistivity of the core sample surface.

[0030] The proposed solution calculates resistivity based on the resistivity conversion value, apparent resistivity, individual standard deviation, and total standard deviation, and performs imaging based on the calculated resistivity. This improves the accuracy of resistivity imaging, offers flexibility, and demonstrates strong ease of use and practicality.

[0031] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the steps of the resistivity imaging method based on core surface resistivity measurement provided in the embodiments of this application; Figure 2 This is a schematic diagram of the core surface resistivity measuring device provided in the embodiments of this application; Figure 3This is a schematic diagram of the structure of the electrode holder provided in the embodiments of this application; Figure 4 This is a schematic diagram of core surface resistivity imaging provided in an embodiment of this application; Figure 5 This is a schematic diagram of the resistivity imaging device based on core surface resistivity measurement provided in the embodiments of this application; Figure 6 This is a schematic diagram of the electronic device provided in the embodiments of this application. Detailed Implementation

[0034] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0035] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or photovoltaic modules, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, photovoltaic modules and / or combinations thereof.

[0036] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0037] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0038] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [the described condition or event] is detected," or "in response to detection of [the described condition or event]."

[0039] Furthermore, in the description of this application, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0040] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in some other embodiments," "in other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0041] With the development of the oil and gas industry, large-scale integrated oil and gas reservoirs are becoming increasingly rare. Domestic and foreign energy companies are paying more and more attention to the exploration of low-porosity, low-permeability oil and gas reservoirs, and the research focus is gradually shifting to unconventional oil and gas resources, including deep carbonate rocks, tight sandstone, and shale. Microscopic petrophysical characterization techniques for these complex reservoirs face challenges, such as diverse lithology, complex pore structure, and strong heterogeneity. Real and effective testing can help geologists identify dominant reservoirs.

[0042] Fractures and cavities serve as storage spaces and flow channels for oil and gas resources, which are crucial for the effective development of these resources. Their internal characteristics and geometric distribution affect the process of comprehensive geological assessment and provide a scientific basis for the selection of oil and gas extraction areas. Drilling cores from wells is an essential step in accurately characterizing fracture and cavity features.

[0043] While meter-scale wellbore microresistivity scanning imaging logging and nanometer-scale core CT scanning technologies exist for multi-scale downhole formation assessment, centimeter-scale physical signal acquisition technologies are still lacking. This limits geophysicists' understanding and assessment of reservoir details. Therefore, developing new downhole centimeter-scale physical signal acquisition technologies will significantly improve the understanding of complex reservoirs based on in-well physical signals, thereby promoting the effective development of oil and gas resources.

[0044] In situations where core samples exhibit rich geological features, peri-well resistivity scanning imaging logging is the primary detection method. Establishing reservoir effectiveness evaluation technology centered on vertical wells and conducting imaging logging interpretation are important technological development directions for the exploration and development of complex oil and gas reservoirs. Taking the carbonate strata of the Sichuan Basin as an example, their complex and variable lithology, diverse micropore types, and the differences in conductivity of different mud systems lead to multiple interpretations in microresistivity imaging logging.

[0045] Therefore, the most common technical method currently used by oil and gas technical service companies is to calibrate microresistivity imaging logging using core samples drilled downhole. The entire wellbore is cylindrical, and the drilled core is also cylindrical. Because the core sleeve has a certain thickness, the well wall measured by imaging logging is not the same as the side of the cylindrical core. When the lithology, porosity, or structure of the formation changes horizontally, the downhole microresistivity image cannot be calibrated using the core.

[0046] To solve this technical challenge, it is urgent to develop an experimental device capable of measuring the electric field characteristics of the side surface of a core cylinder. Furthermore, based on the summary and analysis of core experimental data, a resistivity image library representing different rock characteristics such as lithology and pore type should be formed to further improve the reliability and accuracy of geological inversion based on microresistivity imaging logging.

[0047] In the field of rock electric field detection technology, the vast majority of resistivity measurements are performed on planar rocks. The method of inducing current on the outer surface of columnar cores is unique, and the research on this device can provide new research methods for detecting composite materials of different shapes. Furthermore, by comparing core analysis with electrical imaging logging results, and combining this with electric field distribution characteristic maps, reservoirs can be identified and evaluated more accurately. This is of great significance for oil and gas field development planning and production decisions, and helps improve development efficiency and economic benefits.

[0048] To address the aforementioned deficiencies, this application provides a resistivity imaging method based on core surface resistivity measurement. First, the resistivity conversion value is calculated based on the voltage of each button electrode. Second, the apparent resistivity of the core sample surface is calculated based on the resistivity conversion value and the resistivity of the electrolyte. Third, the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates are calculated based on the apparent resistivity. Then, the resistivity of the core sample surface is calculated based on the individual standard deviations and the total standard deviation. Finally, a core surface resistivity imaging map is obtained based on the resistivity of the core sample surface.

[0049] The proposed solution calculates resistivity based on the resistivity conversion value, apparent resistivity, individual standard deviation, and total standard deviation, and performs imaging based on the calculated resistivity. This improves the accuracy of resistivity imaging, offers flexibility, and demonstrates strong ease of use and practicality.

[0050] The specific process implemented in this application is described below through specific embodiments.

[0051] Please see Figure 1 , Figure 1 This is a schematic diagram illustrating the steps of the resistivity imaging method based on core surface resistivity measurement provided in an embodiment of this application. For example... Figure 1 As shown, the method may include the following steps: S101, based on the measured voltage of each button electrode, calculate the resistivity conversion value of each button electrode.

[0052] According to one embodiment of this application, the resistivity conversion value of each button electrode is calculated based on the measured voltage of each button electrode, including: The resistivity conversion values ​​of each button electrode are calculated using the following formula:

[0053] in, This represents the converted resistivity value. l This indicates the height and position number of the button electrode on the core sample. i Indicates the number of the metal electrode plate. j This indicates the number of the button electrode on the metal plate. This represents the voltage generated on each button electrode under the influence of an alternating current signal. This represents the voltage gain value of each metal plate at each height position. This represents the voltage gain value of all metal plates at each height position.

[0054] S102, based on the resistivity conversion value and the resistivity of the electrolyte, the apparent resistivity of the calibrated core sample surface is calculated.

[0055] According to one embodiment of this application, the apparent resistivity of the calibrated core sample surface is calculated based on the resistivity conversion value and the resistivity of the electrolyte, including: The apparent resistivity of the calibrated core sample surface is calculated using the following formula:

[0056] in, This represents the apparent resistivity of the core sample surface. This indicates the resistivity of the electrolyte. A , B It is a constant.

[0057] S103, based on the apparent resistivity, calculates the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates.

[0058] According to one embodiment of this application, the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates are calculated based on the apparent resistivity, including: The standard deviation of each button electrode is calculated using the following formula:

[0059] in, This indicates the standard deviation of each button electrode. Indicates the first i The first metal electrode plate j The average apparent resistivity of each button electrode at all height locations. N Indicates the number of height positions; The total standard deviation of all button electrodes on all metal plates is calculated using the following formula:

[0060] in, Q This represents the total standard deviation of all button electrodes on all metal plates. This represents the average apparent resistivity of all button electrodes on all metal plates at all height locations. Represents the first position of all height locations i The first metal electrode plate j Average apparent resistivity of each button electrode M = N × Total number of button electrodes.

[0061] S104. Based on the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates, the resistivity of the homogenized core sample surface is calculated.

[0062] According to one embodiment of this application, the resistivity of the equalized core sample surface is calculated based on the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates, including: The resistivity of the homogenized core sample surface is calculated using the following formula:

[0063] in, This indicates the resistivity of the core sample surface.

[0064] S105. Based on the resistivity of the core sample surface, an imaging processing algorithm is used to obtain a resistivity imaging map of the core surface.

[0065] According to one embodiment of this application, different color grades represent different resistivity levels, wherein the expression for the mapping relationship between the resistivity magnitude and the chromaticity pixels is as follows:

[0066]

[0067] in, S Indicates pixel scale factor. This represents the maximum resistivity at all coordinate locations. This represents the minimum resistivity at all coordinate locations. This represents the resistivity value measured at each coordinate position. This represents the converted pixel value.

[0068] According to one embodiment of this application, the core surface resistivity measuring device includes: a computing device, a signal acquisition device, a power supply module, a sample cell, an electrode holder, and an electric displacement stage.

[0069] The computing device, connected to the signal acquisition device, power supply module, and electric displacement stage, is used to control the signal acquisition device and the electric displacement stage. The signal acquisition device is also connected to the electrode holder, used to output AC signals to the button electrodes and receive AC signals output from the electrode holder.

[0070] The power module, also connected to the signal acquisition equipment and the electric displacement stage, outputs AC voltage. The sample holder holds the core sample and electrolyte. The electrode holder moves the electrode on the core sample. The electric displacement stage, also connected to the electrode holder, controls the electrode holder to move on the core sample in preset steps.

[0071] According to one embodiment of this application, the signal acquisition device includes a signal input device and a signal output device. The signal output device is used to output an AC signal to the button electrode, and the signal input device receives the AC signal output by the electrode holder.

[0072] According to one embodiment of this application, the electrolyte includes a sodium chloride solution, and the electric displacement stage includes a stepper motor.

[0073] According to one embodiment of this application, the electrode holder includes: a coaxial annular button electrode array, a shielding electrode, an insulating rubber bushing, a fixing pin, a fixing device, a circuit channel, and a return electrode.

[0074] According to one embodiment of this application, the electrode holder includes: a semi-circular metal electrode plate with an inner arc surface, and an array of button electrodes arranged in the middle of the semi-circular metal electrode plate. The upper and lower rows of button electrodes are staggered, and each button electrode is wrapped with an insulating rubber bushing.

[0075] According to one embodiment of this application, the core surface resistivity measuring device further includes a core fixing device for fixing the core sample.

[0076] According to one embodiment of this application, the technical parameters for resistivity measurement include: rock sample length of 100–500 mm, rock sample diameter of 65–102 mm, and temperature of 24°C. In one embodiment, a rock sample with a length of 200 mm and a diameter of 65 mm is selected as the measurement object to specifically illustrate the solution of this application.

[0077] Please see Figure 2 , Figure 2 This is a schematic diagram of the core surface resistivity measuring device provided in an embodiment of this application. Figure 2 As shown, the device includes: a computer 1, a signal acquisition system 2, a power supply 3, an electric displacement stage 4, a sample cell 5, an electrode holder 6, a core sample 7, a core fixing device 8, and an electrolyte 9 in the sample cell.

[0078] In some embodiments, computer 1 connects to and controls signal acquisition system 2 and electric displacement stage 4. Electrode holder 6 has an inner arc surface of semi-circular metal plate and a button electrode array arranged in the middle of the semi-circular metal plate. Signal acquisition system 2 includes an electrical signal output device and an electrical signal receiving device. The electrical signal output device is connected to the button electrode array, and the electrical signal receiving device is connected to the return electrode of electrode holder 6. Both signal acquisition system 2 and electric displacement stage 4 are connected to power supply 3 for power.

[0079] An electric displacement stage 4 is provided on the side of the sample cell 5. The bottom of the electric displacement stage 4 is fixed on the frame of the sample cell 5 and is connected to the electrode holder 6 by a metal rod.

[0080] Please see Figure 3 , Figure 3 This is a schematic diagram of the electrode holder provided in an embodiment of this application. Figure 3 As shown, the electrode holder 6 is provided with a coaxial annular button electrode array (not shown in the figure), a fixing pin 6.1, a fixing device 6.2, a line channel 6.3 and a return electrode 6.4.

[0081] In some embodiments, the power supply 3 controls the output of a 5V AC voltage to transmit current to the signal acquisition system 2. The computer 1 connects the signal acquisition system 2 and the electric displacement stage 4, and controls the electric displacement stage 4 through integrated software to drive the electrode holder 6 to move vertically. In some embodiments, an appropriate amount of electrolyte 9 is injected into the sample cell 5. The electrolyte 9 is generally a sodium chloride solution. The signal acquisition system 2 integrates electrical signal output and electrical signal reception, and is connected to the button electrode and the reflux electrode respectively, converting and transmitting the received signal to the computer 1.

[0082] In some embodiments, the electric displacement stage 4 is controlled by a stepper motor to move the electrode holder 6 by a stepping step, with a movement range of 0~500mm and a minimum accuracy of 0.01mm for the stepping step. The electric displacement stage 4 must be zeroed and its initial position determined before use.

[0083] In some embodiments, an annular button electrode array, a shielding electrode, an insulating rubber bushing, and a return electrode are coaxially arranged from bottom to top inside the electrode holder 6. The shielding electrode surrounds the annular button electrode array, which is in direct contact with the rock surface.

[0084] In some embodiments, the annular button electrode array consists of two semi-circular metal plates with a total of 88 circular button electrodes on the two plates. Each plate has two rows of 44 button electrodes, and the upper and lower rows of button electrodes are staggered. Each electrode is wrapped with an insulating rubber bushing.

[0085] In some embodiments, the core sample is fixed in the sample slot by a fixing device 8, which is a hollow disc with three equally spaced block-shaped buckles on the upper part, so that the core sample is locked or released vertically at 90 degrees, ensuring the stability of the core when the electrode holder is in operation.

[0086] In some embodiments, the electric displacement stage 4 is located on the side of the sample chamber and is horizontally connected to the fixed position 6.2 of the electrode holder 6 via a metal rod. The moving step size and movement mode of the button array are precisely controlled by a stepper motor, driving the electrode holder 6 to move vertically until the measurement is completed. The upper part of the electrode holder 6 has a return electrode 6.4, so that the current emitted by the button electrode during measurement flows into the return electrode 6.4 to form a circuit.

[0087] In some embodiments, a computer connects to and controls a signal acquisition system and a stepper motor. The computer software allows users to click "measure," automatically recording the current position (y) and the button electrode array test results. After the measurement is completed, the stepper motor controls and moves the electrode holder to begin measuring the next point. Once all measurements are finished, all data is saved to a designated directory. Based on imaging processing algorithms, the program plots and presents a core resistivity image, thus achieving automated measurement via the software.

[0088] According to one embodiment of this application, a measurement method using the above-described rock surface resistivity measuring device includes the following steps: 1) After cleaning the cylindrical rock sample, immerse it in a water tank with a saline solution of high mineral content until the rock sample reaches constant weight; 2) After aligning the two electrode holders 6, connect them with the fixing pin 6.1. Then, after passing the rock sample through the return electrode, insert it into the through hole formed after the two electrode holders are aligned. Rotate the fixing pin 6.1 to make the rock sample fit with the circular button electrodes of the two electrode holders 6. The wires connected to each circular button electrode and the wires connected to the semi-circular metal plate extend from the line channel 4 and connect to the signal acquisition system 2. 3) The signal transmitting and receiving device simultaneously outputs an AC signal to the circular button electrodes, forming a circuit with the return electrode on the upper part of the electrode holder; the voltage value formed by each circular button electrode under the action of the AC signal is measured by a sampling resistor. , l Number the height position of the circular button electrode on the rock sample. i This refers to the numbering of the semi-circular metal electrode plates. j The number of the circular button electrode on the semi-circular metal plate; 4) Based on the voltage value measured by the button electrodes Calculate the resistivity conversion value for each circular button electrode. :

[0089] in, The voltage gain value for each semi-circular metal plate at each height position. The voltage gain (plate gain) of the two semi-circular metal plates at each height position.

[0090] Converted from resistivity and the resistivity of salt solutions The apparent resistivity of the calibrated rock sample surface can then be obtained. :

[0091] in, A , B It is a constant; According to apparent resistivity Calculate the standard deviation of each round button electrode:

[0092] in, For the first i The first semi-circular metal electrode plate j The average apparent resistivity of a circular button electrode at all height locations. N This represents the number of height positions.

[0093] According to apparent resistivity Calculate the standard deviation of all circular button electrodes on all semi-circular metal plates:

[0094] in, This represents the average apparent resistivity of all circular button electrodes on all semi-circular metal plates at all height positions. For all height positions i The first semi-circular metal electrode plate j The average apparent resistivity of the circular button electrodes. M for N × The total number of all round button electrodes; Calculate the resistivity of the rock sample surface after equalization. :

[0095] The resistivity values ​​obtained above Different color grades represent different levels of resistivity, thus clearly and intuitively showing the resistivity at various locations in the rock sample. The pixel mapping relationship between resistivity amplitude and color intensity is as follows:

[0096]

[0097] Where S is the pixel scale coefficient. This represents the maximum resistivity at all coordinate locations. This represents the minimum resistivity at all coordinate locations. The resistivity value measured at each coordinate position. These are the converted pixel values.

[0098] Please participate Figure 4 , Figure 4 This is a schematic diagram of core surface resistivity imaging provided in an embodiment of this application, specifically a schematic diagram of the electrical imaging results of the core surface sampled at a spacing of 0.2 mm. The results show that pores of different sizes differ in size in the imaging image, and this measurement result can help analyze the electrical characteristics of the pores in the core.

[0099] Figure 4 The black stripes in the middle correspond to the fractures in the core, which verifies that the electrical characteristics differ under different porosity features. Calculating the porosity can provide guidance for the exploration of actual oil and gas reservoirs.

[0100] Therefore, the electrode layout and imaging method of this application can accurately reflect the formation porosity characteristics and electrical response, improve the effect of underground resource exploration and engineering monitoring, and also improve the quality and efficiency of well logging data interpretation, which has a guiding role in the development of oil and gas reservoirs.

[0101] The resistivity imaging method based on core surface resistivity measurement provided in this application first calculates the resistivity conversion value of each button electrode based on the voltage of each button electrode. Then, it calculates the apparent resistivity of the core sample surface based on the resistivity conversion value and the resistivity of the electrolyte. Next, it calculates the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates based on the apparent resistivity. Then, it calculates the resistivity of the core sample surface based on the individual standard deviations and the total standard deviations. Finally, it obtains a core surface resistivity imaging map based on the resistivity of the core sample surface.

[0102] The proposed solution calculates resistivity based on the resistivity conversion value, apparent resistivity, individual standard deviation, and total standard deviation, and performs imaging based on the calculated resistivity. This improves the accuracy of resistivity imaging, offers flexibility, and demonstrates strong ease of use and practicality.

[0103] This application utilizes a high-precision electric field sensor and image processing algorithm to achieve accurate measurement of the electric field on the rock surface and accurate identification of pore features. It enables uniform movement and precise positioning of the arc-shaped focusing electrode on the rock surface, and, in conjunction with the signal acquisition system, can accurately record electrical parameters at different locations.

[0104] The proposed method can extract the resistivity distribution of rock surfaces, and then analyze the relationship between different lithologies, different pore space types and electric fields, providing important electrical property information for oil and gas exploration.

[0105] The research and development effects of this application are specifically reflected in two aspects: First, by measuring the surface resistivity distribution characteristics of a large number of full-diameter rock samples, a rock surface resistivity image plate library covering various lithologies, micropore types, and rock structures is established, solving the problem of identifying electrical characteristics and rock types; Second, the plate library is used to conduct quality assessment of the interpretation results of downhole microresistivity imaging logging, improving the utilization rate of downhole microresistivity imaging logging data and providing a basis for the rock physical characterization and geological evaluation of high-quality reservoirs.

[0106] This application aims to achieve the following key objectives: (1) High-precision measurement: The designed device will adopt advanced sensing technology and precision machining process to ensure that the measurement accuracy reaches within 0.1 inches, accurately capturing the tiny resistivity changes on the rock surface, thereby accurately reflecting the complex geological structure and pore characteristics.

[0107] (2) Strong adaptability: The electrode clamp will have wide applicability to different rock sizes, rock compositions, structural features and mineralization. It can work stably in a variety of conductive solution environments and meet the measurement needs under different geological conditions.

[0108] (3) Convenient operation and positioning: Through the fine design of the stepper motor, users can easily adjust and fix the electrode device at any height to ensure that the electrode maintains the best contact with the rock surface. At the same time, the integrated control software can indicate the potential distribution of the core surface at the current position in real time, reduce human error and improve work efficiency.

[0109] (4) Comprehensive analysis capability: The supporting software system will integrate data analysis function, which can automatically process measurement data, quickly generate electrical imaging maps of rock surfaces, and combine core rolling scan photos to help researchers to deeply interpret the stratigraphic structure, judge the sedimentary environment and oil and gas potential, and effectively solve the problem of multiple interpretations of electrical imaging logging.

[0110] In summary, this application not only fills the gap in the domestic field of experimental detection of rock surface resistivity, but will also greatly promote the technological progress of geophysical and rock physics research, providing strong technical support for the effective development of complex oil and gas reservoirs.

[0111] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0112] Corresponding to the method in the above embodiments, Figure 5 This is a schematic diagram of the resistivity imaging device based on core surface resistivity measurement provided in an embodiment of this application. For ease of explanation, only the parts relevant to the embodiment of this application are shown.

[0113] Reference Figure 5 The device includes: The first calculation unit 501 is used to calculate the resistivity conversion value of each button electrode based on the measured voltage of each button electrode. The second calculation unit 502 is used to calculate the apparent resistivity of the core sample surface after calibration based on the resistivity conversion value and the resistivity of the electrolyte. The third calculation unit 503 is used to calculate the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates based on the apparent resistivity. The fourth calculation unit 504 is used to calculate the resistivity of the equalized core sample surface based on the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates. Imaging unit 505 is used to perform imaging based on the resistivity of the core sample surface using an imaging processing algorithm to obtain a resistivity imaging map of the core surface.

[0114] It should be noted that the information interaction and execution process between the above-mentioned devices / units are based on the same concept as the method embodiments of this application. For details on their specific functions and technical effects, please refer to the method embodiments section, and they will not be repeated here.

[0115] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0116] Figure 6 This is a schematic diagram of the structure of the electronic device 6 provided in an embodiment of this application. Figure 6 As shown, the electronic device 6 of this embodiment includes: at least one processor 601 ( Figure 6 Only one is shown in the diagram), memory 603, and computer program 602 stored in memory 603 and executable on at least one processor 601, wherein processor 601 executes computer program 602 to implement the steps in the above method embodiments.

[0117] Electronic device 6 can be a computing device such as a desktop computer, laptop, handheld computer, or mobile phone. This electronic device 6 may include, but is not limited to, a processor 601 and a memory 603. Those skilled in the art will understand that... Figure 6 This is merely an example of electronic device 6 and does not constitute a limitation on electronic device 6. It may include more or fewer components than shown, or combine certain components, or different components, such as input / output devices, network access devices, etc.

[0118] The processor 601 may be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware photovoltaic modules, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0119] In some embodiments, memory 603 may be an internal storage unit of electronic device 6, such as a hard disk or memory of electronic device 6. In other embodiments, memory 603 may be an external storage device of electronic device 6, such as a plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, etc., equipped on electronic device 6. Furthermore, memory 603 may include both internal and external storage units of electronic device 6. Memory 603 is used to store operating system, application programs, boot loader, data, and other programs, such as program code of computer programs. Memory 603 may also be used to temporarily store data that has been output or will be output.

[0120] If the integrated units described above are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, when implementing all or part of the processes in the methods of the above embodiments of this application, it can be accomplished by a computer program instructing related hardware. This computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps applied to the method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. A computer-readable storage medium can include at least: any entity or device capable of carrying computer program code to a computing device / electronic device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, such as a USB flash drive, a portable hard drive, a magnetic disk, or an optical disk. In some jurisdictions, according to legislation and patent practice, a computer-readable storage medium cannot be an electrical carrier signal or a telecommunication signal.

[0121] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in the various method embodiments described above.

[0122] This application provides a computer program product that, when run on an electronic device, causes the electronic device to execute the steps described in the various method embodiments above.

[0123] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0124] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0125] In the embodiments provided in this application, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. The device / electronic device embodiments described above are merely illustrative, and the division of modules or units described above is only a logical functional division. In actual implementation, there may be other division methods. For example, multiple units or photovoltaic modules may be combined or integrated into another system, and some features may be ignored. Furthermore, the indirect coupling, direct coupling, or communication connection shown or discussed may be through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0126] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0127] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the above embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A resistivity imaging method based on core surface resistivity measurement, characterized in that, Based on a core surface resistivity measuring device, the method includes: Based on the measured voltage of each button electrode, the resistivity conversion value of each button electrode is calculated. Based on the resistivity conversion value and the resistivity of the electrolyte, the apparent resistivity of the core sample surface after calibration is calculated. Based on the apparent resistivity, the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates are calculated. The resistivity of the core sample surface after equalization was calculated based on the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates. Based on the resistivity of the core sample surface, an imaging processing algorithm is used to obtain a resistivity image of the core surface.

2. The resistivity imaging method based on core surface resistivity measurement according to claim 1, characterized in that, Based on the measured voltage of each button electrode, the resistivity conversion value of each button electrode is calculated, including: The resistivity conversion values ​​of each button electrode are calculated using the following formula: in, This represents the converted resistivity value. l This indicates the height and position number of the button electrode on the core sample. i Indicates the number of the metal electrode plate. j This indicates the number of the button electrode on the metal plate. This represents the voltage generated on each button electrode under the influence of an alternating current signal. This represents the voltage gain value of each metal plate at each height position. This represents the voltage gain value of all metal plates at each height position.

3. The resistivity imaging method based on core surface resistivity measurement according to claim 1, characterized in that, Based on the resistivity conversion value and the resistivity of the electrolyte, the apparent resistivity of the calibrated core sample surface is calculated, including: The apparent resistivity of the calibrated core sample surface is calculated using the following formula: in, This represents the apparent resistivity of the core sample surface. This indicates the resistivity of the electrolyte. A , B It is a constant.

4. The resistivity imaging method based on core surface resistivity measurement according to claim 1, characterized in that, Based on the apparent resistivity, the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates are calculated, including: The standard deviation of each button electrode is calculated using the following formula: in, This indicates the standard deviation of each button electrode. Indicates the first i The first metal electrode plate j The average apparent resistivity of each button electrode at all height locations. N Indicates the number of height positions; The total standard deviation of all button electrodes on all metal plates is calculated using the following formula: in, Q This represents the total standard deviation of all button electrodes on all metal plates. This represents the average apparent resistivity of all button electrodes on all metal plates at all height locations. Represents the first position of all height locations i The first metal electrode plate j Average apparent resistivity of each button electrode M = N × Total number of button electrodes.

5. The resistivity imaging method based on core surface resistivity measurement according to claim 1, characterized in that, Based on the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates, the resistivity of the equalized core sample surface was calculated, including: The resistivity of the homogenized core sample surface is calculated using the following formula: in, This indicates the resistivity of the core sample surface.

6. The resistivity imaging method based on core surface resistivity measurement according to any one of claims 1-5, characterized in that, Different color levels represent different resistivity values. The expression for the mapping relationship between resistivity magnitude and chromaticity pixels is as follows: in, S Indicates pixel scale factor. This represents the maximum resistivity at all coordinate locations. This represents the minimum resistivity at all coordinate locations. This represents the resistivity value measured at each coordinate position. This represents the converted pixel value.

7. The resistivity imaging method based on core surface resistivity measurement according to claim 1, characterized in that, The device includes: A computing device, connected to a signal acquisition device, a power module, and an electric displacement stage, is used to control the signal acquisition device and the electric displacement stage; The signal acquisition device is also connected to the electrode holder for outputting AC signals to the button electrodes and receiving AC signals output by the electrode holder. The power module is also connected to a signal acquisition device and an electric displacement stage, and is used to output AC voltage; Sample cell, used to hold core samples and electrolyte; The electrode holder is used for moving on the core sample; The electric displacement stage is also connected to the electrode holder and is used to control the electrode holder to move on the core sample with a preset movement step size.

8. The resistivity imaging method based on core surface resistivity measurement according to claim 7, characterized in that, The signal acquisition device includes a signal input device and a signal output device; the signal output device is used to output an AC signal to the button electrode, and the signal input device receives the AC signal output by the electrode holder.

9. The resistivity imaging method based on core surface resistivity measurement according to claim 7, characterized in that, The electrolyte includes a sodium chloride solution, and the electric displacement stage includes a stepper motor.

10. The resistivity imaging method based on core surface resistivity measurement according to claim 7, characterized in that, The electrode holder includes: a coaxial annular button electrode array, a shielding electrode, an insulating rubber bushing, a fixing pin, a fixing device, a circuit channel, and a return electrode.

11. The resistivity imaging method based on core surface resistivity measurement according to claim 10, characterized in that, The electrode holder includes: a semi-circular metal plate with an inner arc surface, and an array of button electrodes arranged in the middle of the semi-circular metal plate; the upper and lower rows of button electrodes are staggered, and each button electrode is wrapped with an insulating rubber bushing.

12. The resistivity imaging method based on core surface resistivity measurement according to claim 7, characterized in that, The device also includes a core fixing device for fixing core samples.

13. A resistivity imaging device based on core surface resistivity measurement, characterized in that, The device includes: The first calculation unit is used to calculate the resistivity conversion value of each button electrode based on the measured voltage of each button electrode. The second calculation unit is used to calculate the apparent resistivity of the core sample surface after calibration based on the resistivity conversion value and the resistivity of the electrolyte. The third calculation unit is used to calculate the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates based on the apparent resistivity. The fourth calculation unit is used to calculate the resistivity of the equalized core sample surface based on the standard deviation of each button electrode and the total standard deviation of all button electrodes on all metal plates. The imaging unit is used to perform imaging based on the resistivity of the core sample surface using an imaging processing algorithm to obtain a resistivity imaging map of the core surface.

14. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the resistivity imaging method based on core surface resistivity measurement as described in any one of claims 1-12.

15. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the resistivity imaging method based on core surface resistivity measurement as described in any one of claims 1-12.

16. A computer program product, characterized in that, When the computer program product is run on an electronic device, the electronic device performs the resistivity imaging method based on core surface resistivity measurement as described in any one of claims 1-12.

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