An electrode-solution method core resistivity imaging device

Abstract

The application provides an electrode-solution method core resistance imaging device, a mechanical part of which comprises: a water tank for storing electrolyte; a base for clamping a core; a core side resistance plate for measurement, which is closed by an automatic locking device; a circular ring-shaped return electrode; and an automatic walking machine for controlling the up-and-down movement of the plate. A circuit module comprises: a signal generator for generating alternating voltage; a sampling resistance connected with a button electrode; a switch switching module for transmitting the voltage on the sampling resistance; and a data acquisition module for collecting data to a computer terminal. The automatic locking device clamps the plate, so that the plate is tightly attached to the core and moves. The automatic locking device enables the plate to move without damaging the core itself, and the resistance of each point on the circumference of the core is quickly measured. The plate collects the resistance of the core at different positions, and the data of the electrodes on the plate are transmitted to the data acquisition system in real time. The data are converted into the image of the tested core by using an imaging algorithm, and the surface features of the core are imaged.

Description

Technical Field

[0001] The present invention belongs to the technical field of geophysical exploration, and in particular relates to a core resistance imaging device and a core resistance measurement imaging method. Background Art

[0002] A core is a cylindrical rock sample taken from a hole using an annular core drill bit and other coring tools according to the needs of geological exploration or engineering.

[0003] Measuring core electrical resistance is the primary method for describing reservoir properties. Changes in resistance reflect changes in reservoir porosity and structure. Traditional core resistance measurement methods use the quadrupole method, which involves direct electrical contact with the core. This method requires contact with the sample, uses electrodes to input current, and measures the voltage between the two electrodes in the rock sample to calculate the core resistance. This method has poor adaptability and cannot perform rapid non-destructive testing. Furthermore, due to the size of the four electrodes, it cannot simultaneously measure both fine structural defects and large-scale defects in the core. In addition to the quadrupole method, radio frequency testing is also used to measure core resistance, using the electric field of an induction coil to measure the core resistance. This method does not contact the core, but cannot truly reflect the core resistance in an underground environment and cannot measure and image the surface defect characteristics of the core. Summary of the Invention

[0004] In response to the above-mentioned technical problems, the present invention aims to provide a core resistance imaging device, which can measure the resistance of the core in a simulated underground logging environment and perform imaging processing on the measured core data.

[0005] According to the present invention, an electrode-solution core resistance imaging device is provided, comprising: a water tank, an electrolyte, a core clamping device, a plate, a return electrode, a robotic arm, a motor, a circuit module, an imaging system, and a sampling resistor. The core clamping device is located in the water tank and is used to clamp and fix the core. The core is cylindrical, and the plate includes a shielding electrode and a button electrode. The shielding electrode is a hollow barrel-shaped structure, and one or more circles of button electrodes are arranged around the inner wall of the barrel-shaped structure. The button electrode and the shielding electrode are isolated by insulating material. The return electrode is a ring-shaped structure. The plate is fixed to the end of the robotic arm, and the return electrode is fixed to the middle of the robotic arm. The axes of the core, plate, and return electrode coincide, so that the plate and the core to be measured can be effectively connected while avoiding direct contact with each other. The motor drives the robotic arm to move the plate and return electrode up and down along the axis. The electrolyte is located in the water tank and submerges the return electrode. The circuit module is directly connected to the shielding electrode, and then connected to the sampling resistor and then to the button electrode. The imaging system images the core according to the voltage of the sampling resistor.

[0006] The imaging method of the imaging device is as follows:

[0007] A circuit module is used to generate a sinusoidal AC voltage, which is transmitted to the button electrode and the shield electrode respectively. The current flows through the sampling resistor and the button electrode into the core and forms a loop through the return electrode.

[0008] The motor controls the robotic arm to move in steps of a certain length, pausing for a period of time after each step to collect data in the following ways:

[0009] Establish (X, Z) coordinate axes, where the X axis represents the data of different button electrodes at the same depth point m, and the Z axis represents the data of different depth points of the same button electrode i;

[0010] X(i) = πD / N*i, where i is the corresponding button electrode, i∈(0, N-1), D is the diameter of the core, N is the number of button electrodes, and X(i) represents the X-axis position of the i-th button electrode;

[0011] Z(m)=H0+h*m, where m is the corresponding depth point, m∈(0,p-1), H0 is the starting measurement position, the test distance is H=h*p, p is the number of steps, h is the step size, and Z(m) is the Z-axis position at the depth point m;

[0012] Where V is the output voltage of the signal generator, v(X, Z) is the voltage value of the button electrode on the sampling resistor corresponding to the horizontal position X and depth Z, R is the resistance value of the sampling resistor, and R(X, Z) represents the core surface resistance value at the position (X, Z);

[0013] The core is imaged using R(X,Z), and the image is exported in the form of coordinates (X,Z).

[0014] Furthermore, when the button electrodes are multiple circles, adjacent circles of button electrodes are staggered.

[0015] Furthermore, the diameter of the core is D mm, the diameter of the electrode plate is D+b mm, b=0.1-3.0 mm, and the diameter of the button electrode is 0.2 mm-10 mm.

[0016] Furthermore, the circuit module and other components are connected by shielded wires.

[0017] Furthermore, a switching module is provided in the circuit module to group all the button electrodes and collect the voltages of the sampling resistors in groups; in each group, the voltages of the sampling resistors corresponding to each button electrode are collected one by one in sequence through the switching module.

[0018] This invention designs a core resistance imaging test device that can simulate well logging environments. Its core test results can be compared with downhole measurements. By employing plates equipped with elastic locking mechanisms and a removable return electrode, the device rapidly measures the resistance of various points along the core's circumference without damaging the plate button electrodes or the core. Using an automatic stepping motor in conjunction with a data acquisition circuit, the device enables continuous, automated measurement of the core and rapid imaging of its resistance distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram showing a core resistance measuring device according to the present invention is shown;

[0020] Figure 2 shows a schematic diagram of an imaging system according to the present invention;

[0021] Figure 3 A schematic diagram showing an embodiment of signal generation and acquisition according to the present invention is shown;

[0022] Figure 4 A schematic diagram showing an embodiment of a single-row arrangement of electrode plates according to the present invention;

[0023] Figure 5 A schematic diagram showing an embodiment of a multi-row arrangement of electrode plates according to the present invention.

[0024] Figure 6 An imaging diagram in a test example according to the present invention is shown.

[0025] In the figure: 1. water tank; 2. electrolyte; 3. core clamping device; 4. core; 5. electrode plate; 6. return electrode; 7. motor manipulator; 8. motor operating console; 9. computer control terminal and imaging system; 10. circuit module; 11. signal generator; 12. electrode plate clamping device; 13. switch circuit switching module; 14. signal processing module; 15. data acquisition module; 16. sampling resistor; 17. insulator; 18. shielding electrode; 19. button electrode. DETAILED DESCRIPTION

[0026] An electrode-solution core resistance imaging device includes: a water tank, an electrolyte, a core clamping device, a plate, a return electrode, a robotic arm, a motor, a circuit module, an imaging system, and a sampling resistor. The core clamping device is located in the water tank and is used to clamp and fix the core. The core is cylindrical. The plate includes a shielding electrode and a button electrode. The shielding electrode is a hollow barrel-shaped structure. One or more circles of button electrodes are arranged around the inner wall of the barrel-shaped structure. The button electrode and the shielding electrode are isolated by insulating material. The return electrode is a ring structure. The plate is fixed to the end of the robotic arm, and the return electrode is fixed to the In the center, the axes of the core, electrode plate, and return electrode coincide, ensuring effective electrical connection between the electrode plate and the core being measured while avoiding direct contact. A motor drives a robotic arm, moving the electrode plate and return electrode up and down along the axis. The electrolyte is contained in a water tank, submerging the return electrode. The circuit module is directly connected to the shielding electrode, which is then connected to the sampling resistor and then to the button electrode. The button electrode on the electrode plate of the core resistance imaging device can be designed in two ways, including but not limited to single-turn and multi-turn button electrodes. The multi-turn button electrode design can improve electrode plate coverage and calibrate data at the same depth point. An automatic locking device is used to close the electrode plate to ensure effective electrical contact with the core.

[0027] The shielded wire is used to transmit the test signal and avoid interference of the AC signal between the electrodes. The shielding electrode is a conductive plate embedded with a button electrode, and the shielding electrode and the button electrode are insulated by an insulator; the core clamping device uses a rigid spring to apply external force to the electrode plate to keep it locked, and its size is determined by the diameter D of the standard core.

[0028] The transmitting voltage is provided by the circuit module, and the output voltage amplitude V (0.1-10V) and frequency K (100-20kHz) are adjustable.

[0029] The sampling resistor, with a variable resistance R (1Ω-1KΩ), is located between the transmitting circuit and the button electrode. The voltage V across the sampling resistor is detected by a differential switching circuit, filtered and amplified by a differential amplifier circuit capable of amplifying tiny signals, and then sent to the data acquisition system. The return electrode (ring) is located directly above or below the plate, and its vertical distance from the plate is adjustable.

[0030] The core resistance imaging device has N button electrodes arranged in an array along the inner side of the electrode plate, and the diameter of the button electrodes is d (0.2 mm to 10 mm).

[0031] The plate locking device of the core resistance imaging device applies force to the plate through an elastic element, so that the plate closes and forms a circular shape inside, thereby ensuring effective conduction between the plate and the core to be measured while avoiding direct contact with each other.

[0032] The electrode plate of the core resistance imaging device is connected to the control motor, and the computer sets the parameters of the control motor, including the number of steps p and the dwell time t of a single depth point, to perform automatic measurement of the core.

[0033] The core electrical resistance imaging device uses software designed for the imaging device to generate images from stored data using a pre-programmed algorithm. Images are exported as (X, Z) coordinates, where the X-axis represents data from different button electrodes at the same depth m, and the Z-axis represents data from different depths for the same button electrode i. Coordinates are determined using the following formula:

[0034] X(i) = πD / N*i, where i is the corresponding button electrode, i∈(0, N-1), D is the diameter of the core, and N is the number of button electrodes;

[0035] Z(m)=H0+h*m, where m is the corresponding depth point, m∈(0, P-1), H0 is the starting measurement position, the test distance is H=h*p, and h is the step size;

[0036] Where V is the output voltage of the signal generator, v(X, Z) is the voltage value of the button electrode on the sampling resistor corresponding to the horizontal position X and depth Z, R is the resistance value of the sampling resistor, and R(X, Z) is the surface resistance value of the core;

[0037] The core resistance imaging device uses equalization processing, error correction and other algorithms to process the image during imaging.

[0038] According to the present invention, a core resistance measurement method is also provided, which uses the core resistance measurement device provided by the present invention, including the following steps:

[0039] Select the appropriate core clamping device and electrode plate based on the core size being measured. Connect the electrode plate to the control motor and secure the test core to the base, ensuring the core is vertical. Prepare the electrolyte, ensuring the electrolyte level is above the return electrode of the electrode plate.

[0040] A signal generator is used to generate a ±2.5V 2Khz sinusoidal AC voltage, which is transmitted to the plate button electrode and the shielding electrode respectively. The current flows through the sampling resistor and the button electrode into the core and forms a loop through the return electrode.

[0041] The switching module collects the voltage value on the sampling resistor corresponding to each button electrode in turn, and after amplification, it is collected by the data acquisition system in the form of differential voltage and transmitted to the computer for storage.

[0042] After the imaging processing program processes the raw data to obtain the corresponding (X, Z, R) coordinate related imaging data, it generates a characteristic image corresponding to the core surface through algorithms such as equalization and error processing.

[0043] The present invention will be described below with reference to the accompanying drawings.

[0044] Figure 1 FIG. 1 shows the structure of a core resistance measuring device 100 according to the present invention. Figure 1 and Figure 2 As shown, a core resistance measuring device includes a water tank 1, an electrolyte 2, a core clamping device 3, a core, a plate 5, a return electrode 6, a motor manipulator 7, a motor operating table 8, a computer control terminal and imaging system 9, a circuit module 10, and a plate clamping device 11; Figure 3 As shown, the circuit module 10 is electrically connected to the sampling resistor 12, shield electrode 13, and button electrode 15 via wires. Multiple button electrodes 15 are densely distributed on the shield electrode 13 and separated by insulating rings 14 to form an electric field shield. After flowing through the core, the output current is grounded through the return electrode 6 to form a loop. The circuit module 10 controls the electrical switching of the sampling resistor 12 corresponding to each button electrode 15. The control motor console 8 can manually operate the control motor arm 7, or it can be automatically controlled by the computer control terminal 9.

[0045] According to a specific embodiment of the present invention, the core resistance measuring device includes two electrode plate clamping devices 12 of different sizes, such as Figure 4 、 5 As shown, the 105mm electrode plate 5 is a single-row array button electrode 15, which can measure the core with a core diameter of 105mm+1mm, and the 65mm electrode plate 5 is a double-row array button electrode 15, which can measure the core with a diameter of 65mm+1mm.

[0046] According to the present invention, a core resistance measurement method is also provided. The method uses the core resistance measurement device provided by the present invention and includes the following steps.

[0047] A 65mm electrode plate 5 is selected according to the core size, and a plate clamping device of corresponding size is selected to fix the electrode plate. A salt solution with a sodium chloride to water mass ratio of 3:100 is prepared in the water tank 8. The core is fixed with the core clamping device 1 so that the core maintains close contact with the electrode plate and is perpendicular to the bottom of the water tank. The computer control terminal 9 controls the circuit module 10 to output an AC signal to the electrode plate 5.

[0048] The circuit module 10 is used to control the sampling resistor 12 channels corresponding to each button electrode to open and close in a cycle in sequence, and multiple circumferential points at the same depth of the core are measured in sequence. When powered on, an AC voltage of the same phase is output to each button electrode 15 at the same time, and at the same time, an AC voltage consistent with that of each button electrode is output to the shielding electrode 13. The button electrode 15 has the same potential as the shielding electrode 13, and the current can flow through the core to the return electrode 6. The resistance distribution of the core is uneven, and its resistance change is mapped by the voltage change on the sampling resistor 12. The circuit module 10 collects and stores the voltage signal on each sampling resistor 12 in turn, and obtains the electrical signals of all button electrodes 15 at one depth point at a time. The circuit module 10 differentially amplifies the changing electrical signal on the sampling resistor 12, and sends it to the computer control terminal 9 after processing, and displays it on the computer control terminal 9 in the form of curves, tables, etc. The computer control terminal 9 controls the motor manipulator 6 to move the electrode plate 5 along the core 4 at a constant speed, while collecting data at each depth point. The imaging system 9 performs imaging processing on the collected data to obtain a surface feature map of the core.

[0049] In this embodiment, the AC frequency of the AC power is variable to achieve fixed-point frequency-variable scanning of the core, and then the resistance measurement data of the core surface is collected and stored through the circuit module 10 .

[0050] In one embodiment, after the resistance measurement data is saved, it is transmitted to the prepared imaging software 7, the measurement parameters paired with it are set, and the test file is imported to obtain the surface imaging map of the measured core, such as Figure 6 shown.

Claims

1. An electrode-solution core electrical resistance imaging device, comprising: A water tank, an electrolyte, a core clamping device, a plate, a return electrode, a robotic arm, a motor, a circuit module, an imaging system, and a sampling resistor. The core clamping device is located in the water tank and is used to clamp and fix the core. The core is cylindrical. The plate includes a shielding electrode and a button electrode. The shielding electrode is a hollow barrel-shaped structure. One or more circles of button electrodes are arranged around the inner wall of the barrel-shaped structure. The button electrode and the shielding electrode are isolated by insulating material. The return electrode is a ring-shaped structure. The plate is fixed to the end of the robotic arm, and the return electrode is fixed to the middle of the robotic arm. The axes of the core, plate, and return electrode coincide. The plate and the core to be tested can be effectively connected while avoiding direct contact with each other. The motor drives the robotic arm to move the plate and return electrode up and down along the axis. The electrolyte is located in the water tank and submerges the return electrode. The circuit module is directly connected to the shielding electrode, and then connected to the sampling resistor and then to the button electrode; the imaging system images the core according to the voltage of the sampling resistor; The imaging method of the imaging device is as follows: A circuit module is used to generate a sinusoidal AC voltage, which is transmitted to the button electrode and the shield electrode respectively. The current flows through the sampling resistor and the button electrode into the core and forms a loop through the return electrode. The motor controls the robotic arm to move in steps of a certain length, pausing for a period of time after each step to collect data in the following ways: Establish (X, Z) coordinate axes, where the X axis represents the data of different button electrodes at the same depth point m, and the Z axis represents the data of different depth points of the same button electrode i; X(i) = πD / N*i, where i is the corresponding button electrode, i∈(0, N-1), D is the diameter of the core, N is the number of button electrodes, and X(i) represents the X-axis position of the i-th button electrode; Z(m)=H0+h*m, where m is the corresponding depth point, m∈(0,p-1), H0 is the starting measurement position, the test distance is H=h*p, p is the number of steps, h is the step size, and Z(m) is the Z-axis position at the depth point m; Where V is the output voltage of the signal generator, v(X, Z) is the voltage value of the button electrode on the sampling resistor corresponding to the horizontal position X and depth Z, R is the resistance value of the sampling resistor, and R(X, Z) represents the core surface resistance value at the position (X, Z); The core is imaged using R(X,Z), and the image is exported in the form of coordinates (X,Z).

2. The electrode-solution core electrical resistance imaging device according to claim 1, characterized in that: When the button electrodes are multiple circles, adjacent circles of button electrodes are arranged in a staggered manner.

3. The electrode-solution core electrical resistance imaging device according to claim 1, characterized in that: The diameter of the core is D mm, the diameter of the electrode plate is D+b mm, b=0.1-3.0 mm, and the diameter of the button electrode is 0.2 mm-10 mm.

4. The electrode-solution core electrical resistance imaging device according to claim 1, characterized in that: The circuit module and other components are connected by shielded wires.

5. The electrode-solution core electrical resistance imaging device according to claim 1, characterized in that: A switching switch module is set in the circuit module to group all the button electrodes and collect the voltages of the sampling resistors in groups; in each group, the voltages of the sampling resistors corresponding to each button electrode are collected one by one in sequence through the switch module.

Images