Underground current aggregation and attenuation simulation device and simulation method

Abstract

The invention relates to the technical field of underground resource drilling and production engineering, in particular to an underground current gathering and attenuation simulation device and method, and the device comprises a power supply module which is used for generating alternating current; the mounting seat is provided with a mounting cavity, and the mounting cavity is filled with a conductive first filling material; the test module comprises an accident well sleeve and a rescue well sleeve, the accident well sleeve and the rescue well sleeve are both located in the mounting cavity and inserted in the first filling material, and a plurality of detection assemblies capable of detecting the magnitude of current are arranged on the accident well sleeve; the electrode assembly is connected with the power supply module, the electrode assembly comprises a first electrode and a second electrode, and the first electrode and the second electrode are both arranged in the first filling material and can form a closed loop with the power supply module and the test module. Theoretical support can be provided for field tests, so that an operator can accurately measure and control the relative position of the rescue well and the accident well, and the working efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of underground resource drilling and production engineering, and is an underground current gathering and attenuation simulation device and a simulation method. Background Art

[0002] Rescue well technology is the main technology for solving problems such as blowouts and fires on drilling platforms. How to accurately measure and control the relative position of the rescue well and the accident well has become the core technology of rescue well operations.

[0003] Traditional inclinometers and distance measurement technologies are difficult to meet the requirements of measurement and control accuracy due to the cumulative errors. The ranging error not only increases with the increase of detection depth, but is also affected by the casing of the accident well. The closer to the casing of the accident well, the greater the ranging error.

[0004] In recent years, active magnetic ranging technology based on low-frequency injection current has made significant breakthroughs in rescue wells. This ranging technology avoids cumulative errors and greatly improves ranging accuracy. Among them, ranging systems represented by Wellspot guidance tools have been successfully applied to rescue operations in rescue wells.

[0005] At present, domestic research on this technology has only achieved certain results in theory and algorithm, but has not yet achieved simulation of actual on-site conditions, and cannot conduct comprehensive simulation experiments on different parameters to provide theoretical support for subsequent field tests. Summary of the invention

[0006] The present invention provides an underground current accumulation and attenuation simulation device and simulation method, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problem that the prior art fails to simulate the actual situation on site and cannot conduct comprehensive simulation experiments on different parameters to provide theoretical support for subsequent field tests.

[0007] One of the technical solutions of the present invention is achieved by the following measures: a downhole current accumulation and attenuation simulation device, comprising:

[0008] A power supply module, used for generating an alternating current;

[0009] A mounting seat, the mounting seat having a mounting cavity filled with a first conductive filling material;

[0010] A test module, the test module includes an accident well casing and a rescue well casing, the accident well casing and the rescue well casing are both located in the installation cavity and inserted in the first filling material, and the conductivity of the accident well casing and the rescue well casing is greater than the conductivity of the first filling material, and the accident well casing is provided with a plurality of detection components capable of detecting the magnitude of the current;

[0011] The electrode assembly is connected to the power supply module. The electrode assembly includes a first electrode and a second electrode. The first electrode and the second electrode are both arranged in a first filling material and can form a closed loop with the power supply module and the test module. The alternating current generated by the power supply module diffuses to the first filling material through the first electrode and then gathers on the periphery of the accident well casing.

[0012] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions:

[0013] The above-mentioned detection component can be a non-contact ammeter, and multiple detection components are mounted on the accident well casing and arranged at intervals along the length extension direction of the accident well casing; and / or, the length of the rescue well casing is smaller than the length of the accident well casing, and there is a first preset distance between the rescue well casing and the accident well casing.

[0014] The end face of the above-mentioned first filling material in the installation cavity can be a filling end face, and the ends of the accident well casing and the rescue well casing close to the opening of the mounting seat are flush with the filling end face; and / or, it also includes a first cable, a second cable and a third cable, one end of the first cable is connected to the power supply module, the other end of the first cable is connected to the first electrode through the second cable, and the second electrode is connected to the power supply module through the third cable.

[0015] The utility model may further include a base, the mounting seat is detachably mounted on the base, a roller is arranged on a side of the base away from the mounting seat, and a brake mechanism is arranged on the roller.

[0016] It may also include a blocking module, which includes a blocking protrusion, a handle and a discharge port. The discharge port is arranged on the side wall at the bottom of the mounting seat, the blocking protrusion is installed in the discharge port, and the handle is arranged on the side of the blocking protrusion away from the discharge port.

[0017] The second technical solution of the present invention is achieved by the following measures: A method for simulating downhole current accumulation and attenuation, comprising the following steps:

[0018] Provided is a downhole current gathering and attenuation simulation device, which is the downhole current gathering and attenuation simulation device mentioned above;

[0019] The test module, the first filling material and the electrode assembly are installed in the installation cavity, and the test module, the electrode assembly and the power supply module form a closed loop, and the power supply module is turned on to allow the alternating current generated by the power supply module to diffuse to the first filling material through the first electrode, and then gather on the periphery of the accident well casing;

[0020] Obtain the test value of each test piece, calculate and fit the curve to analyze the data.

[0021] The following is a further optimization and / or improvement of the second technical solution of the above invention:

[0022] The following steps may also be included:

[0023] Keep the relative position of the first electrode and the accident well casing in the horizontal direction unchanged, then move the first electrode longitudinally for multiple times, each moving distance is the second preset distance L1, and obtain the detection value of each detection component, wherein the value range of the second preset distance L1 is 45cm-55cm;

[0024] Alternatively, the distance between the first electrode and the bottom of the mounting base is kept constant, and then the first electrode is moved horizontally for multiple times, and each movement distance is a third preset distance, and the detection value of each detection component is obtained, wherein the value range of the third preset distance L2 is 7.5 cm-90 cm;

[0025] Alternatively, the position of the first electrode remains unchanged, and then the current intensity output by the power supply module is increased or decreased multiple times, and the value of the current intensity increased or decreased each time is a, and the detection value of each detection component is obtained, where the value range of a is 8A-60A.

[0026] Before installing the test module into the installation cavity, a scale line may be drawn on the accident well casing at intervals of a fourth preset distance L3, wherein the value range of the fourth preset distance is 8 cm-12 cm.

[0027] When the test module and the electrode assembly are installed in the installation cavity, the following steps may be specifically included:

[0028] The accident well casing is placed in the installation cavity and placed in a vertical state; a first filling material is filled into the installation cavity, and when the first filling material is filled to the position where the scale line is located, a detection component is set at a corresponding position on the accident well casing;

[0029] Continue to fill the first filling material into the installation cavity. When the first filling material is filled to the first preset position, place the first electrode into the installation cavity, and make the distance between the central axis of the first electrode and the central axis of the accident well casing be a fifth preset distance;

[0030] Continue to fill the first filling material into the installation cavity, and when the first filling material is filled to the second preset position, place the rescue well casing in the installation cavity in a vertical state;

[0031] Continue to fill the first filling material into the installation cavity until the rescue well casing is completely immersed in the first filling material; bury the second electrode in the first filling material.

[0032] After obtaining the experimental data, the distance between the two wells and the magnetic field intensity at each point on the accident well can be calculated using the formula:

[0033]

[0034] in,

[0035]

[0036]

[0037]

[0038] Where: d is the distance from the current dividing point to the scale where the current peak value on the bushing is located; α c is the average well inclination angle of the rescue well section; r e is the radius of the equivalent uniform formation cylinder of the accident well casing; σ e is the formation conductivity; σ c is the casing conductivity; r c is the casing radius; h c is the thickness of the casing wall; H is the magnetic field intensity; μ0 is the vacuum magnetic permeability; z is the distance the current flows downward along the casing of the accident well; I Z is the current flowing downward along the accident well casing at z; r is the distance between the accident well axis and the probe in the rescue well; H z is the current in the casing of the accident well I Z The magnetic field strength generated at the peak current density.

[0039] The downhole current gathering and attenuation simulation device of the present invention can verify the relevant theoretical model of the active magnetic ranging technology based on low-frequency injection current in the rescue well. The setting of the accident well casing and the rescue well casing in the simulation device is proportionally reduced according to the actual size of the accident well and the rescue well at the drilling site to be simulated, and the detection component can automatically detect the current intensity on the accident well casing. The first electrode can be moved horizontally or vertically to change the position of the first electrode relative to the accident well casing. In this way, the change law of the current on the accident well casing can be obtained, the change law of the intensity of the alternating magnetic field can be obtained, and then the change law of the relative position between the accident well casing and the rescue well casing can be obtained. In the actual process of drilling the rescue well, theoretical support can be provided for the field test, so that the operator can accurately measure and control the relative position of the rescue well and the accident well, and improve the work efficiency. The downhole current gathering and attenuation simulation method of the present invention can reflect the influence of the change of the injection current intensity on the current on the accident well casing by obtaining the change law of the current on the accident well casing under specific circumstances, thereby providing favorable theoretical guidance for the actual on-site rescue well drilling, reducing unnecessary operation steps, and thus reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Attached Figure 1It is a schematic diagram of the structure of the downhole current accumulation and attenuation simulation device according to an embodiment of the present invention.

[0041] Attached Figure 2 It is a side structural schematic diagram of the downhole current accumulation and attenuation simulation device according to an embodiment of the present invention.

[0042] Attached Figure 3 It is a structural schematic diagram of a mounting base of a downhole current accumulation and attenuation simulation device according to an embodiment of the present invention.

[0043] Attached Figure 4 It is a structural schematic diagram of a plugging module of a downhole current accumulation and attenuation simulation device according to an embodiment of the present invention.

[0044] Attached Figure 5 It is a structural schematic diagram of the base of the downhole current accumulation and attenuation simulation device according to an embodiment of the present invention.

[0045] Attached Figure 6 It is a schematic structural diagram of the accident well casing of the downhole current accumulation and attenuation simulation device according to an embodiment of the present invention.

[0046] Attached Figure 7 It is a schematic structural diagram of the rescue well casing of the downhole current accumulation and attenuation simulation device according to an embodiment of the present invention.

[0047] Attached Figure 8 It is a schematic structural diagram of the first electrode of the downhole current accumulation and attenuation simulation device according to an embodiment of the present invention.

[0048] Attached Fig. 9 It is a schematic structural diagram of the second electrode of the downhole current accumulation and attenuation simulation device according to an embodiment of the present invention.

[0049] Attached Fig.10 This is a curve diagram of current changes on the accident well casing according to an embodiment of the present invention.

[0050] Attached Fig.11 4 is a diagram of the simulation results of the model current distribution of an embodiment of the present invention.

[0051] Attached Fig.12 This is a current field cloud diagram of the XZ section of the model according to an embodiment of the present invention.

[0052] Attached Fig.13 FIG. 4 is a current field cloud diagram at the XY cross section of the first electrode according to an embodiment of the present invention.

[0053] Attached Fig.14 It is a flow chart of the method for simulating downhole current accumulation and attenuation according to an embodiment of the present invention.

[0054] The codes in the accompanying drawings are: 10 is a power supply module, 11 is a power supply box, 12 is an AC power supply, 20 is a mounting seat, 21 is a discharge port, 22 is a first filling material, 23 is a mounting cavity, 31 is an accident well casing, 32 is a rescue well casing, 40 is a first electrode, 50 is a second electrode, 60 is a first cable, 70 is a second cable, 80 is a third cable, 90 is a base, 91 is a roller, 100 is a blocking module, 101 is a blocking protrusion, 102 is a handle, and 103 is a support plate. DETAILED DESCRIPTION

[0055] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0056] In the present invention, for the convenience of description, the description of the relative position relationship of each component is described according to the layout of the drawings in the specification, such as: the position relationship of front, back, up, down, left, right, etc. is determined according to the layout direction of the drawings in the specification.

[0057] The present invention will be further described below in conjunction with embodiments and drawings:

[0058] Embodiment 1: As attached Figure 1 To Attachment Fig.14 As shown, the downhole current gathering and attenuation simulation device includes: a power supply module 10, which is used to generate an alternating current; a mounting seat 20, the mounting seat 20 has a mounting cavity 23, and the mounting cavity 23 is filled with a first conductive filling material 22; a test module, the test module includes an accident well casing 31 and a rescue well casing 32, the accident well casing 31 and the rescue well casing 32 are both located in the mounting cavity 23 and inserted in the first filling material 22, and the conductivity of the accident well casing 31 and the rescue well casing 32 is greater than the conductivity of the first filling material 22, and the accident well casing 31 is provided with a plurality of detection components capable of detecting the current size; an electrode assembly, the electrode assembly is connected to the power supply module 10, the electrode assembly includes a first electrode 40 and a second electrode 50, the first electrode 40 and the second electrode 50 are both arranged in the first filling material 22, and can form a closed loop with the power supply module 10 and the test module; the alternating current generated by the power supply module 10 diffuses to the first filling material 22 through the first electrode 40, and then gathers on the periphery of the accident well casing 31.

[0059] In an embodiment of the present invention, the detection component is a non-contact ammeter, and multiple detection components are mounted on the accident well casing 31 and arranged at intervals along the length extension direction of the accident well casing 31; and / or, the length of the rescue well casing 32 is less than the length of the accident well casing 31, and there is a first preset distance between the rescue well casing 32 and the accident well casing 31.

[0060] In an embodiment of the present invention, the end face of the first filling material 22 in the installation cavity 23 is the filling end face, and the ends of the accident well casing 31 and the rescue well casing 32 close to the opening of the mounting seat 20 are flush with the filling end face; and / or, it also includes a first cable 60, a second cable 70 and a third cable 80, one end of the first cable 60 is connected to the power supply module 10, the other end of the first cable 60 is connected to the first electrode 40 through the second cable 70, the second electrode 50 is connected to the power supply module 10 through the third cable 80, and the first cable 60 and the third cable 80 are arranged on the outside of the mounting seat 20, and the second cable 70 is arranged in the installation cavity 23.

[0061] In the embodiment of the present invention, the underground current accumulation and attenuation simulation device further includes a base 90, the mounting seat 20 is detachably mounted on the base 90, and a roller 91 is provided on the side of the base 90 away from the mounting seat 20, so that the simulation device can be moved according to actual needs. In addition, a brake mechanism is provided on the roller 91, and when the simulation device moves to a preset position, the brake structure on the roller 91 can stop the simulation device at this position, so that the staff can carry out subsequent installation or experimental steps conveniently.

[0062] In the embodiment of the present invention, the underground current accumulation and attenuation simulation device further includes a plugging module 100, which includes a plugging protrusion 101, a handle 102 and a discharge port 21. The discharge port 21 is arranged on the side wall at the bottom of the mounting seat 20, the plugging protrusion 101 is installed in the discharge port 21 to block the discharge port 21, and the handle 102 is arranged on the side of the plugging protrusion 101 away from the discharge port 21. When the simulation experiment is over, the staff can take the plugging module 100 off the discharge port 21 through the handle 102, and the filling material is quickly discharged through the discharge port 21. This arrangement can simplify the cleaning process of the simulation device.

[0063] In the embodiment of the present invention, a power supply module 10, a mounting seat 20, a test module and an electrode assembly are provided. The power supply module 10 provides a low-frequency alternating current to the first electrode 40, and the detection assembly is used to detect the current on the accident well casing 31. The low-frequency alternating current provided by the power supply module 10 is dispersed to the first filling material 22 through the first electrode 40, and can be gathered at the accident well casing 31, forming a current flowing upward and downward along the accident well casing 31, and finally received by the second electrode 50.

[0064] When in use, install the experimental device and control the variables to perform experimental simulation. Keep the relative position of the first electrode 40 and the accident well casing 31 in the horizontal direction unchanged, then move the first electrode 40 longitudinally for multiple times, each moving distance is the second preset distance L1, and then obtain the detection value of each detection component, wherein the value range of the second preset distance L1 is 45cm≤L1≤55cm. Keep the distance of the first electrode 40 relative to the bottom of the mounting seat 20 unchanged, then move the first electrode 4040 transversely for multiple times, each moving distance is the third preset distance, and then obtain the detection value of each detection component, wherein the value range of the third preset distance L2 is 7.5cm≤L2≤90cm. Keep the position of the first electrode 40 unchanged, then increase or decrease the current intensity output by the power supply module 10 for multiple times, each increase or decrease in the current intensity is a, and obtain the detection value of each detection component, wherein the value range of a is 8A≤a≤60A; turn off the power supply and clean up the above experimental equipment. Pour out all the first filling material 22, fill the installation cavity 23 with the second filling material, and repeat the above steps, wherein the conductivity of the second filling material is different from that of the first filling material 22. The second filling material can be particles of different lithology, which can be selected according to the needs of the simulation experiment. Pour out all the first filling material 22 in the installation cavity 23, and then repeat the above steps to obtain the influence of different lithologies on the current on the accident well casing 31. After obtaining the experimental data, the distance between the two wells and the magnetic field strength at each point on the accident well are calculated using the formula.

[0065] The embodiment of the present invention can verify the relevant theoretical model of the active magnetic ranging technology based on low-frequency injection current in the rescue well. The setting of the accident well casing 31 and the rescue well casing 32 in the simulation device is proportionally reduced according to the actual size of the accident well and the rescue well at the drilling site to be simulated, and the detection component can automatically detect the current intensity on the accident well casing 31. The first electrode 40 can be moved horizontally or vertically to change the position of the first electrode 40 relative to the accident well casing 31. In this way, the change law of the current on the accident well casing 31 can be obtained, the change law of the intensity of the alternating magnetic field can be obtained, and then the change law of the relative position between the accident well casing 31 and the rescue well casing 32 can be obtained. In the process of actually drilling a rescue well, it can provide theoretical support for field experiments, so that operators can accurately measure and control the relative position of the rescue well and the accident well, and improve work efficiency.

[0066] Embodiment 2: As attached Figure 1 To Attachment Fig.14As shown, the downhole current gathering and attenuation simulation method includes the following steps: providing a downhole current gathering and attenuation simulation device, which is the downhole current gathering and attenuation simulation device mentioned above; loading the test module, the first filling material 22 and the electrode assembly into the installation cavity 23, and making the test module, the electrode assembly and the power supply module 10 form a closed loop, turning on the power supply module 10, so that the alternating current generated by the power supply module 10 diffuses to the first filling material 22 through the first electrode 40, and then gathers on the periphery of the accident well casing 31; obtaining the detection value of each detection component, and calculating and fitting the curve analysis data.

[0067] In an embodiment of the present invention, the downhole current accumulation and attenuation simulation method also includes the following steps: keeping the relative position of the first electrode 40 and the accident well casing 31 in the horizontal direction unchanged, and then moving the first electrode 40 longitudinally for multiple times, each moving distance is the second preset distance L1, and obtaining the detection value of each detection component, wherein the value range of the second preset distance L1 is 45cm-55cm; or, keeping the distance of the first electrode 40 relative to the bottom of the mounting seat 20 unchanged, and then moving the first electrode 40 transversely for multiple times, each moving distance is the third preset distance, and obtaining the detection value of each detection component, wherein the value range of the third preset distance L2 is 7.5cm-90cm; or, keeping the position of the first electrode 40 unchanged, and then increasing or decreasing the current intensity output by the power supply module 10 for multiple times, each increase or decrease in the current intensity is a, and obtaining the detection value of each detection component, wherein the value range of a is 8A-60A; turning off the power supply and cleaning the above-mentioned experimental equipment.

[0068] In an embodiment of the present invention, the downhole current accumulation and attenuation simulation method may further include the following steps: pouring out all the first filling material 22, filling the second filling material into the installation cavity 23, and repeating the above steps, wherein the conductivity of the second filling material is different from the conductivity of the first filling material 22. The second filling material may be particles of different lithology, which may be selected according to the needs of the simulation experiment, pouring out all the first filling material 22 in the installation cavity 23, and then repeating the above steps, so as to obtain the influence of different lithology on the current on the accident well casing 31.

[0069] In the embodiment of the present invention, before the test module is installed in the installation cavity 23, a scale line is drawn on the accident well casing 31 every fourth preset distance L3, wherein the value range of the fourth preset distance is 8 cm-12 cm.

[0070] In the embodiment of the present invention, when the test module and the electrode assembly are installed in the installation cavity 23, the following steps are specifically included: the accident well casing 31 is placed in the installation cavity 23 and is in a vertical state; the first filling material 22 is filled into the installation cavity 23, and when the first filling material 22 is filled to the position where the scale line is located, a detection component is set at the corresponding position on the accident well casing 31; the first filling material 22 is continued to be filled into the installation cavity 23, and when the first filling material 22 is filled to the first preset position, the first electrode 40 is placed in the installation cavity 23, and the distance between the central axis of the first electrode 40 and the central axis of the accident well casing 31 is the fifth preset distance; continue to fill the first filling material 22 into the installation cavity 23, and when the first filling material 22 is filled to the second preset position, place the rescue well casing 32 in the installation cavity 23 in a vertical state; continue to fill the first filling material 22 into the installation cavity 23 until the rescue well casing 32 is completely immersed in the first filling material 22; bury the second electrode 50 in the first filling material 22.

[0071] The specific implementation can be carried out through the following steps:

[0072] (1) Install the experimental device and control the variables to conduct experimental simulation.

[0073] (2) Keep the relative position of the first electrode 40 and the accident well casing 31 in the horizontal direction unchanged, and then move the first electrode 40 in the longitudinal direction for multiple times, each moving distance is the second preset distance L1, and then obtain the detection value of each detection component, wherein the value range of the second preset distance L1 is 45cm≤L1≤55cm.

[0074] (3) Keep the distance between the first electrode 40 and the bottom of the mounting base 20 unchanged, and then move the first electrode 4040 in the horizontal direction for multiple times, each movement distance is a third preset distance, and then obtain the detection value of each detection component, wherein the value range of the third preset distance L2 is 7.5cm≤L2≤90cm.

[0075] (4) Keep the position of the first electrode 40 unchanged, then increase or decrease the current intensity output by the power supply module 10 multiple times, and the value of the current intensity increased or decreased each time is a, and obtain the detection value of each detection component, where the value range of a is 8A≤a≤60A; turn off the power and clean the above experimental equipment.

[0076] (5) Pour out all the first filling material 22, fill the installation cavity 23 with the second filling material, and repeat the above steps, wherein the conductivity of the second filling material is different from that of the first filling material 22. The second filling material can be particles of different lithology, which can be selected according to the needs of the simulation experiment. Pour out all the first filling material 22 in the installation cavity 23, and then repeat the above steps, so as to obtain the influence of different lithology on the current on the accident well casing 31.

[0077] (6) After obtaining the experimental data, the distance between the two wells and the magnetic field intensity at each point on the accident well are calculated using the formula:

[0078]

[0079] in,

[0080]

[0081]

[0082]

[0083] Where: d is the distance from the current demarcation point to the scale where the current peak value on the bushing is located, in meters; α c is the average well inclination angle of the rescue well section, in degrees; r e is the radius of the equivalent uniform formation cylinder of the accident well casing 31, in m; σ e is the formation conductivity, in S / m; σ c is the casing conductivity, in S / m; r c is the casing radius, in m; h c is the thickness of the casing wall, in m; H is the magnetic field intensity, in A / m; μ0 is the vacuum magnetic permeability, in T·m / A; z is the distance the current flows downward along the accident well casing 31, in m; I Z is the current flowing downward along the accident well casing 31z, in A; r is the distance between the accident well axis and the probe in the rescue well, in m; H z is the current I in the accident well casing 31 Z The magnetic field strength generated at the peak current density, in A / m.

[0084] As attached Fig.11 As shown, attached Fig.11The simulation results obtained by the above simulation method are shown in Figure 2, where J is the current density and l is the arc length, i.e. the casing length. The radius of the simulated formation is 2500m, the thickness is 5000m, and the conductivity is 10S / m. The rescue well is located on the axis of the cylindrical formation. The surface casing of the rescue well has a diameter of 500mm, a length of 500m, a thickness of 20mm, and a conductivity of 107S / m. The downhole electrode has a diameter of 50mm, a length of 100mm, and a conductivity of 5.998×107S / m, and is located at the center of the rescue well axis. The casing axis coincides with the accident well axis. The casing has a diameter of 250mm, a length of 5000m, a wall thickness of 20mm, and a conductivity of 107S / m. The distance between the two well axes is 30m. The injection current is 10A.

[0085] The embodiment of the present invention obtains the variation law of the current on the accident well casing 31 under specific circumstances, and then can reflect the influence of the change of the injection current intensity on the current on the accident well casing 31, thereby providing favorable theoretical guidance for the actual on-site rescue well drilling, reducing unnecessary operation steps, and thus reducing costs.

[0086] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A downhole current accumulation and attenuation simulation device, characterized in that include: A power supply module, used for generating an alternating current; A mounting seat, the mounting seat having a mounting cavity filled with a first conductive filling material; A test module, the test module includes an accident well casing and a rescue well casing, the accident well casing and the rescue well casing are both located in the installation cavity and inserted in the first filling material, and the conductivity of the accident well casing and the rescue well casing is greater than the conductivity of the first filling material, and the accident well casing is provided with a plurality of detection components capable of detecting the magnitude of the current; The electrode assembly is connected to the power supply module. The electrode assembly includes a first electrode and a second electrode. The first electrode and the second electrode are both arranged in a first filling material and can form a closed loop with the power supply module and the test module. The alternating current generated by the power supply module diffuses to the first filling material through the first electrode and then gathers on the periphery of the accident well casing.

2. The downhole current accumulation and attenuation simulation device according to claim 1, characterized in that The detection component is a non-contact ammeter, and multiple detection components are mounted on the accident well casing and arranged at intervals along the length extension direction of the accident well casing; and / or the length of the rescue well casing is smaller than the length of the accident well casing, and there is a first preset distance between the rescue well casing and the accident well casing.

3. The downhole current accumulation and attenuation simulation device according to claim 1 or 2, characterized in that The end face of the first filling material in the installation cavity is the filling end face, and the ends of the accident well casing and the rescue well casing close to the opening of the mounting seat are flush with the filling end face; and / or, it also includes a first cable, a second cable and a third cable, one end of the first cable is connected to the power supply module, the other end of the first cable is connected to the first electrode through the second cable, and the second electrode is connected to the power supply module through the third cable.

4. The downhole current accumulation and attenuation simulation device according to claim 1 or 2, characterized in that The utility model also comprises a base, on which a mounting seat is detachably mounted, and a roller is arranged on a side of the base away from the mounting seat, and a brake mechanism is arranged on the roller.

5. The downhole current accumulation and attenuation simulation device according to claim 1 or 2, characterized in that It also includes a blocking module, which includes a blocking protrusion, a handle and a discharge port. The discharge port is arranged on the side wall at the bottom of the mounting seat, the blocking protrusion is installed in the discharge port, and the handle is arranged on the side of the blocking protrusion away from the discharge port.

6. A method for simulating downhole current accumulation and attenuation, characterized in that The following steps are involved: Provided is a downhole current gathering and attenuation simulation device, the downhole current gathering and attenuation simulation device is a downhole current gathering and attenuation simulation device as claimed in any one of claims 1 to 5; The test module, the first filling material and the electrode assembly are installed in the installation cavity, and the test module, the electrode assembly and the power supply module form a closed loop, and the power supply module is turned on to allow the alternating current generated by the power supply module to diffuse to the first filling material through the first electrode, and then gather on the periphery of the accident well casing; Obtain the test value of each test piece, calculate and fit the curve to analyze the data.

7. The downhole current accumulation and attenuation simulation device according to claim 6, characterized in that The following steps are also included: Keep the relative position of the first electrode and the accident well casing in the horizontal direction unchanged, then move the first electrode longitudinally for multiple times, each moving distance is the second preset distance L1, and obtain the detection value of each detection component, wherein the value range of the second preset distance L1 is 45cm-55cm; Alternatively, the distance between the first electrode and the bottom of the mounting base is kept constant, and then the first electrode is moved horizontally for multiple times, and each movement distance is a third preset distance, and the detection value of each detection component is obtained, wherein the value range of the third preset distance L2 is 7.5 cm-90 cm; Alternatively, keep the position of the first electrode unchanged, and then increase or decrease the current intensity output by the power supply module multiple times, and the value of the current intensity increased or decreased each time is a, and obtain the detection value of each detection component, where the value range of a is 8A-60A.

8. The downhole current accumulation and attenuation simulation device according to claim 6 or 7, characterized in that Before installing the test module into the installation cavity, a scale line is drawn on the accident well casing at every fourth preset distance L3, wherein the value range of the fourth preset distance is 8 cm-12 cm.

9. The downhole current accumulation and attenuation simulation device according to claim 6 or 7, characterized in that When the test module and the electrode assembly are installed in the installation cavity, the following steps are specifically included: Place the accident well casing in the installation cavity and keep it in a vertical state; fill the installation cavity with a first filling material, and when the first filling material is filled to the position where the scale line is located, set a detection component at the corresponding position on the accident well casing; Continue to fill the first filling material into the installation cavity. When the first filling material is filled to the first preset position, place the first electrode into the installation cavity, and make the distance between the central axis of the first electrode and the central axis of the accident well casing be a fifth preset distance; Continue to fill the first filling material into the installation cavity, and when the first filling material is filled to the second preset position, place the rescue well casing in the installation cavity in a vertical state; Continue to fill the first filling material into the installation cavity until the rescue well casing is completely immersed in the first filling material; bury the second electrode in the first filling material.

10. The downhole current accumulation and attenuation simulation device according to claim 7, characterized in that After obtaining the experimental data, the distance between the two wells and the magnetic field intensity at each point on the accident well are calculated using the formula: in, Where: d is the distance from the current dividing point to the scale where the current peak value on the bushing is located; α c is the average well inclination angle of the rescue well section; r e is the radius of the equivalent uniform formation cylinder of the accident well casing; σ e is the formation conductivity; σ c is the casing conductivity; r c is the casing radius; h c is the thickness of the casing wall; H is the magnetic field intensity; μ0 is the vacuum magnetic permeability; z is the distance the current flows downward along the casing of the accident well; I Z is the current flowing downward along the accident well casing at z; r is the distance between the accident well axis and the probe in the rescue well; H z is the current in the casing of the accident well I Z The magnetic field strength generated at the peak current density.

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