A rock resistivity measuring device and a rock resistivity measuring method

Abstract

The present invention provides a rock resistivity measuring device, which comprises a reaction shell with a reaction tank, a shell cover for sealing the reaction tank is detachably connected to the reaction shell, and the reaction shell and the shell cover are both made of electrical insulating materials; two opposite sides of the reaction tank are respectively provided with a liquid inlet and a liquid outlet connected to the outlet of a delivery pump and the inlet of a detection box, a water quality detector is arranged in the detection box, and the delivery pump is connected to the liquid supply system; a support net is arranged on the outer surface of the reaction shell, and a resistivity measuring device and a control device are arranged on the support net, a cable groove is arranged at the open end of the reaction shell, and the detection cable of the resistivity measuring device passes through the cable groove to measure the resistance value at both ends of the rock sample; the resistance measuring device, the delivery pump, the liquid supply system, and the water quality detector are all connected to the control device. The invention solves the problem that there is no rock resistivity measuring device for measuring different types of cracks in the prior art, and the influence of cracks on rock resistivity cannot be quantified.

Description

Technical Field

[0001] The present invention relates to the technical field of rock resistivity measuring devices, and in particular to a rock resistivity measuring device and a resistivity measuring method thereof. Background Art

[0002] Fractures (fracture structures in which rocks are broken after being stressed and there is no significant displacement along the fracture surface) are spaces for underground fluid storage and one of the channels for migration. The degree of development of fractures will greatly affect the reserves and migration rate of groundwater. When conducting groundwater exploration, resistivity (a physical quantity that characterizes the electrical conductivity of a substance, measured in ohm-meters. Generally, the higher the mineralization of various salt solutions, the better their electrical conductivity) is an important method. By measuring the electrical conductivity of the formation, it is possible to determine whether there is formation water in the formation within a certain depth range underground and to determine the level of formation water. However, the mineralization of formation water (referring to the amount of a certain ion contained in a unit volume of solution, generally expressed in mg / L), the type of fracture and its degree of development will affect the resistivity measurement results. However, the prior art lacks a rock resistivity measurement device for measuring different types of fractures. Summary of the invention

[0003] In view of the above problems in the prior art, the present invention provides a rock resistivity measuring device and a resistivity measuring method thereof, which solves the problem that there is no rock resistivity measuring device for measuring different types of cracks in the prior art and the influence of cracks on rock resistivity cannot be quantified.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0005] In a first aspect, a rock resistivity measuring device is provided, which comprises a reaction shell having a reaction tank, a shell cover for sealing the reaction tank being detachably connected to the reaction shell, and the reaction shell and the shell cover are both made of electrical insulating materials;

[0006] The two opposite sides of the reaction tank are respectively provided with a liquid inlet and a liquid outlet connected with the outlet of the delivery pump and the inlet of the detection box. A water quality detector is arranged in the detection box, and the delivery pump is connected with the liquid supply system.

[0007] A support net is provided on the outer surface of the reaction shell, and a resistivity measuring device and a control device are provided on the support net. A cable groove is provided at the open end of the reaction shell, and a detection cable of the resistivity measuring device passes through the cable groove to measure the resistance value at both ends of the rock sample.

[0008] The resistance measuring device, the delivery pump, the liquid supply system, and the water quality detector are all connected to the control device.

[0009] Furthermore, an electric valve switch is provided between the detection box and the reaction housing, and the electric valve switch is connected to the control device. When the concentration of the reaction solution does not change, the electric valve switch can prevent the reaction solution from flowing out of the reaction tank all the time, causing waste of the reaction solution.

[0010] Furthermore, an insulating tube with a hollow structure is provided between the side of the reaction tank where the liquid inlet and the liquid outlet are located and the rock sample, and the head of the detection cable of the resistivity measuring device is located in the insulating tube.

[0011] Furthermore, a sealing strip is provided on the open end face of the reaction shell, and the sealing strip is provided with a sealing protrusion embedded in the cable groove, and the reaction shell and the shell cover are both made of plastic. The reaction area surrounded by the reaction tank and the bottom surface of the shell is completely closed by the sealing strip, so the reaction solution delivered by the delivery pump can enter the detection box along the path of "liquid inlet of the reaction tank-rock sample-liquid outlet of the reaction tank", the purpose of which is to make the solution concentration in the rock sample reach the predetermined requirement, and at the same time avoid the reaction solution being outside the rock sample, so as to avoid the resistance value measured by the resistivity measuring device not being at both ends of the rock sample.

[0012] Furthermore, the volume of the reaction area enclosed by the reaction tank and the bottom surface of the shell cover is 1 to 1.3 times the volume of the rock sample. The purpose is to make the rock sample act as a hollow pipe, so that the reaction solution can all pass through the rock sample, so that the measured resistance value is the resistance value at both ends of the rock sample, and the resistivity of the rock sample is highly accurate.

[0013] Furthermore, the liquid supply system includes a plurality of raw liquid cylinders, each of which is provided with a liquid outlet pipe, all of which are connected to the liquid supply main pipe, an electric valve switch connected to the control device is provided between the liquid outlet pipe and the liquid supply main pipe, and the liquid supply main pipe is connected to the inlet of the delivery pump. The control device controls the closing of different electric valve switches to allow reaction solutions of different concentrations in the raw liquid cylinder to enter the reaction tank to change the resistance value of the solution, and then measure the resistivity of the rock sample.

[0014] Furthermore, the control device includes a computing terminal and a display, and the display is connected to the computing terminal. The display can display the current concentration of the reaction solution, the condition of the rock sample and the current resistivity in real time. The concentration of the reaction solution is automatically changed by the computing terminal, and the resistivity formula is obtained according to the first resistivity value range, the second resistivity value range and the third resistivity value range, revealing the influence of the reaction solution concentration, the number of cracks and the width of the cracks on the resistivity of the rock sample.

[0015] Furthermore, the resistance measuring device includes a 1000 Hz digital bridge, which measures the resistance value of the reaction solution at both ends of the rock sample, and then calculates the resistivity of the rock sample.

[0016] In a second aspect, a resistivity measurement method is provided, which specifically comprises the following steps:

[0017] S1. Pump a reaction solution of concentration A into the reaction tank until the reaction solution appears in the detection box;

[0018] S2. At a predetermined temperature, the resistance value r of the reaction solution is measured, and the electrode coefficient K of the reaction shell is calculated;

[0019] S3, placing a rock sample with a crack width of b1, a crack number of d1 and a crack shape of M into a reaction tank;

[0020] S4, pumping a reaction solution of concentration A into the reaction tank, and detecting whether the concentration value of the reaction solution in the detection box is a predetermined concentration, if so, continue to pump the reaction solution until it reaches the predetermined concentration and then enter step S5, otherwise, stop pumping and then enter step S5;

[0021] S5, collecting the resistance value of the reaction solution, and calculating the resistivity of the rock sample according to the electrode coefficient K;

[0022] S6, proceed to steps S7, S9, and S11 respectively;

[0023] S7, judging whether the number of calculated resistivities reaches a predetermined number, if so, proceeding to S8, otherwise returning to set b1=b1+k1, and continuing steps S3-S5 and S7 in sequence, wherein k1 is the crack width growth value;

[0024] S8, recording the current resistivity, and using all resistivities to form the first resistivity range of the rock sample, and then entering S13;

[0025] S9, judging whether the number of resistivities calculated has reached a predetermined number, if so, proceeding to S10, otherwise returning to set A=A+A1, and continuing steps S4-S5 and S9 in sequence, wherein A1 is the growth value of the reaction solution;

[0026] S10, recording the current resistivity, and using all resistivities to form a second resistivity range of the rock sample, and then entering S13;

[0027] S11, judging whether the number of calculated resistivities reaches a predetermined number, if so, proceeding to S12, otherwise returning to set d1=d1+k2, and sequentially continuing steps S3-S5 and S11, wherein k2 is the growth value of the number of cracks;

[0028] S12, recording the current resistivity, and using all resistivities to form a third resistivity range of the rock sample, and then entering S13;

[0029] S13, obtaining a structure index according to the first resistivity range and the second resistivity range, obtaining a concentration index according to the third resistivity range, and calculating a resistivity formula according to the structure index and the concentration index:

[0030]

[0031] Among them, R is the resistivity, p is the fracture angle, m is the structural index, A is the formation water concentration, and n is the concentration index.

[0032] Further, the crack shape M is any one of the following: straight split cracks, angle cracks and mesh cracks. The mesh cracks are formed by alternating straight split cracks and horizontal cracks.

[0033] Furthermore, the electrode coefficient K=r*0.1.

[0034] The beneficial effects of the present invention are as follows: the present solution can automatically pump reaction solutions of different concentrations into the reaction tank by controlling the delivery pump and the liquid supply system through the control device, and decide when to stop pumping the reaction solution according to the data detected by the water quality detector, so as to achieve the effect of the reaction concentration on the rock sample by making the rock sample have reaction solutions of different concentrations. The reaction shell and the shell cover are made of electrically insulating materials in order to reduce the controllable factors in measuring the resistivity of the rock sample and improve the accuracy of the measurement results. Through the cable groove, the detection cable can be arranged to the correct position without affecting the sealing of the reaction shell and the shell cover.

[0035] The rock samples produced by the resistivity measuring device combined with 3D printing technology can have cracks of different shapes, widths and numbers, and the width of the cracks can be made small enough, for example, at the level of 0.1 cm. By changing the shape, width and number of cracks, the influence of the number and width of cracks and the concentration of the reflected solution (equivalent to the mineralization of the actual liquid) on the resistivity of the rock is revealed, and then the resistivity of different rocks can be calculated according to the resistivity formula. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a cross-sectional schematic diagram of a rock resistivity measuring device.

[0037] Figure 2 This is a rear view of a rock resistivity measurement device.

[0038] Figure 3 Schematic diagram of a rock sample with a vertical fracture.

[0039] Figure 4 Schematic diagram of a rock sample with a crack.

[0040] Figure 5 Schematic diagram of a rock specimen with an angle crack.

[0041] Among them, 1. reaction shell; 2. shell cover; 3. delivery pump; 4. detection box; 5. support net; 6. digital bridge; 7. water quality detector; 8. rock sample. DETAILED DESCRIPTION

[0042] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0043] like Figure 1 and 2 As shown, the present solution provides a rock resistivity measuring device, which includes a reaction shell 1 having a reaction tank, a shell cover 2 for sealing the reaction tank being detachably connected to the reaction shell 1, and both the reaction shell 1 and the shell cover 2 are made of plastic material. A sealing strip is provided on the end surface of the opening end of the reaction shell 1, and a sealing groove embedded in the cable groove is provided on the sealing strip to ensure the sealing between the reaction shell 1 and the shell cover 2.

[0044] The two opposite sides of the reaction tank are respectively provided with a liquid inlet and a liquid outlet connected with the outlet of the delivery pump 3 and the inlet of the detection box 4. The detection box 4 is provided with a water quality detector 7, and the delivery pump 3 is connected to the liquid supply system.

[0045] Furthermore, an electric valve switch is provided between the detection box 4 and the reaction shell 1, and the electric valve switch is connected to the control device. The liquid supply system includes a plurality of stock liquid cylinders, each of which is provided with a liquid outlet pipe, all of which are connected to the liquid supply main pipe, an electric valve switch connected to the control device is provided between the liquid outlet pipe and the liquid supply main pipe, and the liquid supply main pipe is connected to the inlet of the delivery pump 3. The delivery pump 3 can adopt a micro water pump with a power of 30W. The electric valve switch can adopt a one-way valve to prevent the reaction solution from flowing back into the reaction tank.

[0046] A support net 5 is provided on the outer surface of the reaction shell 1, and a resistivity measuring device and a control device are provided on the support net 5. A cable groove is provided at the open end of the reaction shell 1, and a detection cable of the resistivity measuring device passes through the cable groove to measure the resistance value at both ends of the rock sample;

[0047] The resistance measuring device, the delivery pump, the liquid supply system, and the water quality detector 7 are all connected to the control device. The resistance measuring device includes a 1000Hz digital bridge 6, and the control device includes a computing terminal and a display, and the display is connected to the computing terminal. The computing terminal can be a single-chip microcomputer, and the display can be a liquid crystal display. In this embodiment, the reaction solution can be a sodium chloride solution.

[0048] Furthermore, the volume of the reaction area enclosed by the reaction tank and the bottom surface of the shell cover 2 is 1.1 times the volume of the rock sample 8, in order to allow a gap between the rock sample and the reaction tank for installing an insulating tube. An insulating tube with a hollow structure is provided between the side of the reaction tank where the liquid inlet and the liquid outlet are located and the rock sample, and the head of the detection cable of the resistivity measuring device is located in the insulating tube. Specifically, a through hole for the head of the detection cable to enter is provided on the side of the insulating tube, or a groove is provided on the end surface of the insulating tube for the detection cable to enter. When in use, the head of the detection cable faces the liquid outlet and the liquid inlet of the reaction tank.

[0049] This solution also provides a resistivity measurement method, which specifically includes the following steps:

[0050] S1, pumping a reaction solution of concentration A into the reaction tank until a reaction solution appears in the detection box 4;

[0051] S2. At a predetermined temperature, the resistance value r of the reaction solution is measured, and the electrode coefficient K of the reaction shell 1 is calculated;

[0052] S3, placing a rock sample 8 with a crack width of b1, a crack number of d1 and a crack shape of M into a reaction tank;

[0053] S4, pumping a reaction solution of concentration A into the reaction tank, and detecting whether the concentration value of the reaction solution in the detection box 4 is a predetermined concentration, if so, continue to pump the reaction solution until it reaches the predetermined concentration and then enter step S5, otherwise, stop pumping and then enter step S5;

[0054] S5, collecting the resistance value of the reaction solution, and calculating the resistivity of the rock sample according to the electrode coefficient K;

[0055] S6, proceed to steps S7, S9, and S11 respectively;

[0056] S7, judging whether the number of calculated resistivities reaches a predetermined number, if so, proceeding to S8, otherwise returning to set b1=b1+k1, and continuing steps S3-S5 and S7 in sequence, wherein k1 is the crack width growth value;

[0057] S8, recording the current resistivity, and using all resistivities to form the first resistivity range of the rock sample, and then entering S13;

[0058] S9, judging whether the number of resistivities calculated has reached a predetermined number, if so, proceeding to S10, otherwise returning to set A=A+A1, and continuing steps S4-S5 and S9 in sequence, wherein A1 is the growth value of the reaction solution;

[0059] S10, recording the current resistivity, and using all resistivities to form a second resistivity range of the rock sample, and then entering S13;

[0060] S11, judging whether the number of calculated resistivities reaches a predetermined number, if so, proceeding to S12, otherwise returning to set d1=d1+k2, and sequentially continuing steps S3-S5 and S11, wherein k2 is the growth value of the number of cracks;

[0061] S12, recording the current resistivity, and using all resistivities to form a third resistivity range of the rock sample, and then entering S13;

[0062] S13, obtaining a structure index according to the first resistivity range and the second resistivity range, obtaining a concentration index according to the third resistivity range, and calculating a resistivity formula according to the structure index and the concentration index:

[0063]

[0064] Among them, R is the resistivity, p is the fracture angle, m is the structural index, A is the formation water concentration, and n is the concentration index.

[0065] The process of obtaining the structural index is as follows: based on the first resistivity value range and the second resistivity value range, two coordinate systems (d1-R and b1-R) are drawn with resistivity as the ordinate axis and crack width or crack number as the abscissa axis, and the d1-R straight line equation and b1-R straight line equation are obtained according to the d1-R coordinate system and the b1-R coordinate system, respectively. At the same time, the points far away from the d1-R straight line and the b1-R straight line are discarded, and the first slope value and the second slope value are obtained according to the d1-R straight line equation and the b1-R straight line equation, respectively, and the average value of the first slope value and the second slope value is used as the structural index.

[0066] The process of obtaining the concentration index is as follows: based on the second resistivity value range, an AR coordinate system is drawn with resistivity as the vertical axis and formation water concentration (the concentration of the reaction solution in this application) as the horizontal axis, and the AR straight line equation is obtained according to the AR coordinate system. At the same time, the points far away from the AR straight line are discarded, and the third slope value is obtained according to the AR straight line equation, and the third slope value is used as the concentration index.

[0067] Furthermore, if Figure 3-5 As shown, the crack shape M is any one of the following: straight cracks, angle cracks and mesh cracks.

[0068] Furthermore, the electrode coefficient K=r*0.1.

Claims

1. A rock resistivity measuring device, characterized in that: It comprises a reaction housing (1) having a reaction groove, the reaction housing (1) being detachably connected to a housing cover (2) for sealing the reaction groove, and the reaction housing (1) and the housing cover (2) are both made of electrically insulating materials; Two opposite sides of the reaction tank are respectively provided with a liquid inlet and a liquid outlet which are connected to the outlet of the delivery pump (3) and the inlet of the detection box (4); a water quality detector (7) is provided in the detection box (4); and the delivery pump (3) is connected to a liquid supply system; The outer surface of the reaction shell (1) is provided with a support net (5), and the support net (5) is provided with a resistivity measuring device and a control device, and the open end of the reaction shell (1) is provided with a cable groove, and the detection cable of the resistivity measuring device passes through the cable groove to measure the resistance value at both ends of the rock sample; The resistivity measuring device, the delivery pump, the liquid supply system, and the water quality detector (7) are all connected to the control device; The resistivity measurement method of the device comprises the following steps: S1, pumping a reaction solution of concentration A into the reaction tank until the reaction solution appears in the detection box (4); S2. At a predetermined temperature, measuring the resistance value r of the reaction solution and calculating the electrode coefficient K of the reaction shell (1); S3, the crack width is The number of cracks is The rock sample with the fracture shape M is placed in the reaction tank; S4, pumping a reaction solution of concentration A into the reaction tank, and detecting whether the concentration of the reaction solution in the detection box (4) is a predetermined concentration. If so, stop pumping and then proceed to step S5. Otherwise, continue pumping the reaction solution until it reaches the predetermined concentration and then proceed to step S5. S5, collecting the resistance value of the reaction solution, and calculating the resistivity of the rock sample according to the electrode coefficient K; S6, proceed to steps S7, S9, and S11 respectively; S7, determine whether the number of resistivity calculated reaches the predetermined number, if so, enter S8, otherwise return to the command , and then proceed to steps S3-S5 and S7, wherein, is the crack width growth value; S8, recording the current resistivity, and using all resistivities to form the first resistivity range of the rock sample, and then entering S13; S9, determine whether the number of resistivity calculated reaches the predetermined number, if so, enter S10, otherwise return to the command , and then proceed to steps S4-S5 and S9, wherein is the growth value of the reaction solution; S10, recording the current resistivity, and using all resistivities to form a second resistivity range of the rock sample, and then entering S13; S11, determine whether the number of resistivity calculated reaches the predetermined number, if so, enter S12, otherwise return to command , and then proceed to steps S3-S5 and S11, wherein, is the crack quantity growth value; S12, recording the current resistivity, and using all resistivities to form a third resistivity range of the rock sample, and then entering S13; S13, obtaining a structure index according to the first resistivity range and the second resistivity range, obtaining a concentration index according to the third resistivity range, and calculating a resistivity formula according to the structure index and the concentration index: Among them, R is the resistivity, p is the fracture angle, m is the structural index, A is the formation water concentration, and n is the concentration index.

2. The rock resistivity measuring device according to claim 1, characterized in that: An electric valve switch is provided between the detection box (4) and the reaction housing (1), and the electric valve switch is connected to the control device.

3. The rock resistivity measuring device according to claim 1, characterized in that: An insulating tube with a hollow structure is provided between the side of the reaction tank where the liquid inlet and the liquid outlet are located and the rock sample, and the head of the detection cable of the resistivity measuring device is located in the insulating tube.

4. The rock resistivity measuring device according to claim 1, characterized in that: The open end surface of the reaction shell (1) is provided with a sealing rubber strip, and the sealing rubber strip is provided with a sealing protrusion embedded in the cable groove. The reaction shell (1) and the shell cover (2) are both made of plastic.

5. The rock resistivity measuring device according to claim 1, characterized in that: The volume of the reaction area enclosed by the reaction tank and the bottom surface of the shell cover (2) is 1 to 1.3 times the volume of the rock sample.

6. The rock resistivity measuring device according to any one of claims 1 to 5, characterized in that: The liquid supply system comprises a plurality of raw liquid cylinders, each of which is provided with a liquid outlet pipe, all of which are connected to a liquid supply main pipe, an electric valve switch connected to a control device is provided between the liquid outlet pipe and the liquid supply main pipe, and the liquid supply main pipe is connected to an inlet of the delivery pump (3).

7. The rock resistivity measuring device according to claim 6, characterized in that: The resistance measuring device comprises a 1000 Hz digital bridge (6).

8. The rock resistivity measuring device according to claim 1, characterized in that: The crack shape M is a straight crack, an angle crack or a mesh crack.

9. The rock resistivity measuring device according to claim 1, characterized in that: The electrode coefficient K=r*0.1.

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