Excitation method and system for pipe string of adjacent well

Abstract

The invention provides an adjacent well pipe column excitation method and system, and relates to the technical field of petroleum and natural gas engineering, and the method comprises the steps that a ground power supply device applies potential to an underground electric leakage system and an earth surface electric leakage system of a first drilling well; the applied potential generates alternating current flowing up and down at a current demarcation point of the casing of the second drilling well, and the alternating current excites an alternating induced magnetic field around the casing; the first drilling well is a drilling well; electric field intensities in different media are calculated according to drilling fluid information in a drilling well and surrounding stratum information, and then the electric field intensity at the position of a current demarcation point on a casing pipe in a second drilling well can be determined; and determining an alternating induced magnetic field excited by the alternating current flowing on the sleeve according to the electric field intensity. The alternating induced magnetic field is detected in the exploring tube of the first drilling well, a signal source is provided for fine control over the well track of the drilling well, and the method can be applied to the technical fields of collision prevention, communication, fish detection, old well reentry and the like of wells of complex structures.

Description

Technical Field

[0001] The present application relates to the field of oil and gas engineering technology, and in particular to an adjacent well tubular column excitation method and system. Background Art

[0002] Complex structure wells are advanced well types for developing oil and gas resources such as low permeability, shale oil and gas, and tight oil and gas. In the process of drilling complex wells, once a blowout accident occurs, emergency rescue must be carried out to reduce the huge losses caused by the accident. In order to effectively achieve the purpose of extinguishing the fire of oil and gas wells or controlling the blowout, the purpose of drilling the rescue well is to pump the well-killing fluid into the accident well where the blowout occurred. Accurately controlling the directional drilling trajectory of the rescue well so that it can reach the target area close enough to the accident well, or even geometrically intersect with the trajectory of the accident well, has an important impact on the success of the rescue well, and poses severe technical challenges to the measurement and control of the wellbore trajectory. Before the emergence of magnetic guidance drilling technology, it was often necessary to drill multiple rescue wells, and success was possible only after repeated attempts. At the same time, magnetic guidance technology can also be widely used in directional drilling projects such as dual horizontal wells and cluster well collision prevention. Active magnetic guidance technology can ensure the sealing of key parts of abandoned wells and completely seal the wellbore to prevent gas leakage and unnecessary fluid flow by drilling wells to connect abandoned wells in depleted oil and gas reservoirs. This process effectively creates a confined space around the abandoned well to store gas.

[0003] The existing method for measuring the wellbore position is to measure the well depth, well inclination and azimuth at multiple measuring points at different well depths and obtain them by combining a specific calculation method. Specifically, during the drilling process, an inclinometer or other measuring tools are regularly used to measure the wellbore in real time or regularly. The measurement content includes well depth, well inclination, azimuth, and measuring tool position.

[0004] However, the positions of each measuring point in the well obtained by the existing borehole position measurement method are based on the position of the previous measuring point. Therefore, the measurement error of a certain measuring point is the accumulation of the measurement errors of all measuring points in the upper well section. This cumulative error cannot be ignored, which makes the conventional borehole position measurement method unsuitable for drilling projects of complex wells where the relative positions of adjacent wells need to be finely controlled. Therefore, how to avoid the problem that the cumulative error in the existing borehole position measurement method has a great impact on the borehole position measurement results? A method for exciting the adjacent well string that is suitable for the actual situation of the drilling site is proposed to provide a signal source for the precise measurement and control of the relative positions of adjacent wells. Summary of the invention

[0005] The present application provides a method for exciting the tubular column of an adjacent well, so as to avoid the problem that the accumulated error existing in the existing wellbore position measurement method has a great influence on the measurement result, and proposes a method for exciting the tubular column of an adjacent well suitable for the actual situation at the drilling site, so as to provide a signal source for the refined control of the relative position of the adjacent well.

[0006] In a first aspect, the present application provides an adjacent well tubular column excitation method, which is applied to an adjacent well tubular column excitation system, the system comprising: a first drilling well, a second drilling well, a ground power supply device, a surface leakage system and a control device for the first drilling well; wherein the first drilling well is a positive drilling well, the first drilling well comprises a downhole leakage system, the second drilling well comprises a casing, and the ground power supply device is respectively connected to the downhole leakage system and the surface leakage system; the method comprises:

[0007] The ground power supply device applies electric potential to the downhole leakage system and the surface leakage system of the first well respectively; wherein the applied electric potential generates an alternating current flowing up and down at the current boundary point of the casing of the second well via the stratum, and the alternating current excites an alternating induced magnetic field around the casing;

[0008] The control device determines the electric field intensity of the current demarcation point on the casing of the second well according to the surrounding formation information of the first well and the distance between the first well and the second well;

[0009] The control device determines the alternating induced magnetic field around the bushing excited by the current flowing on the bushing according to the electric field strength at the current demarcation point;

[0010] The control device uses the alternating induced magnetic field as a signal source to control the drilling trajectory of the first well.

[0011] Further, the underground leakage current system comprises a first insulating cable, a first insulating assembly and an underground leakage current short joint;

[0012] The surface power supply device applies an electric potential to the downhole leakage current system of the first drilling well, comprising: the electric potential generated by the surface power supply device is sequentially transmitted to the downhole leakage current short joint via the first insulating cable and the first insulating assembly, so as to apply the electric potential to the formation using the downhole leakage current short joint;

[0013] The current demarcation point is a point on the casing of the second wellbore that is radially opposite to the downhole leakage short joint of the downhole leakage system;

[0014] and / or;

[0015] The applied potential is a low-frequency square wave voltage;

[0016] and / or;

[0017] The surface leakage current system comprises a second insulating cable and a surface leakage current short joint.

[0018] Through the above-mentioned technical means, the electric potential is applied to the formation through the downhole leakage short section of the downhole leakage system and the surface leakage short section of the surface leakage system, generating an alternating current on the casing of the second drilling well, and then generating an alternating induced magnetic field. The function of the insulating component and the insulating cable is to avoid the magnetic field interference caused by the axial flow of current on the downhole electrode.

[0019] Further, the step of determining the electric field strength of the current demarcation point on the casing of the second well according to the surrounding formation information of the first well and the distance between adjacent wells of the first well and the second well comprises:

[0020] Obtaining the radius of the drilling fluid column of the first well;

[0021] Determining a weight factor of the drilling fluid in the first well, an electric potential of the downhole leakage sub, and an electric potential of the drilling fluid in the first well;

[0022] Determine the weight factor of the formation and the electrical potential of the formation;

[0023] The electric field strength at any position is calculated using the following formula according to the weight factor of the drilling fluid in the first well, the potential of the downhole leakage sub, the potential of the drilling fluid in the first well, the weight factor of the formation and the potential of the formation:

[0024]

[0025] Where r1 is the radial distance between any position in the formation and the downhole leakage short joint; E r1,z is the electric field strength at a radial distance r1 and a vertical distance z=0 from the underground leakage short joint; r f is the radius of the drilling fluid column in the first well; ρ1 is the weight factor of the drilling fluid in the first well; ρ2 is the weight factor of the formation; A is the potential of the downhole leakage short joint at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint; B is the potential of the drilling fluid in the first well at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint; C is the potential of the formation at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint;

[0026] Substituting the adjacent spacing into r1 in the above formula, the electric field intensity of the current demarcation point is obtained.

[0027] Further, the determining of the weight factor of the drilling fluid in the first well, the potential of the downhole leakage sub, and the potential of the drilling fluid in the first well comprises:

[0028] Obtaining the conductivity of the first drilling fluid and the conductivity of the formation;

[0029] The weight factor of the drilling fluid in the first well, the potential of the downhole leakage sub, and the potential of the drilling fluid in the first well are calculated respectively using the following formulas:

[0030]

[0031] Wherein, ρ1 is the drilling fluid weight factor of the first drilling well; U is the alternating voltage; R is the resistance of the downhole leakage short joint; σ f is the conductivity of the drilling fluid in the first well; σ e is the conductivity of the formation; r1 is the radial distance between the target position in the formation and the downhole leakage short joint in the first drilling well; r f is the radius of the drilling fluid column in the first drilling well; A is the potential of the downhole leakage short joint at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint; B is the potential of the drilling fluid in the first drilling well at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint; K0(·) is a zero-order second-kind deformed Bessel function; K1(·) is a first-order second-kind deformed Bessel function; J0(·) is a zero-order first-kind deformed Bessel function; J1(·) is a first-order first-kind deformed Bessel function.

[0032] Further, the determining of the weight factor of the formation and the electric potential of the formation includes:

[0033] Obtaining the conductivity of the drilling fluid and the conductivity of the formation in the first drilling well;

[0034] The weight factor of the formation and the electric potential of the formation are calculated respectively using the following formulas:

[0035]

[0036] Wherein, ρ2 is the weight factor of the formation; U is the alternating voltage; R is the resistance of the downhole leakage short joint; σ f is the conductivity of the first drilling fluid; σ e is the conductivity of the formation; r1 is the radial distance between the target position in the formation and the downhole leakage short joint; r f is the radius of the drilling fluid column in the first drilling well; C is the potential of the formation at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint; K0(·) is a zero-order second-kind deformed Bessel function; K1(·) is a first-order second-kind deformed Bessel function; J0(·) is a zero-order first-kind deformed Bessel function; J1(·) is a first-order first-kind deformed Bessel function.

[0037] Optionally, determining the alternating induced magnetic field around the bushing induced by the current flowing through the bushing according to the electric field strength at the current demarcation point includes:

[0038] According to the electric field intensity at the current demarcation point, the conductivity of the casing of the second wellbore and the cross-sectional area, the alternating induced magnetic field excited around the casing is calculated using the following formula:

[0039]

[0040] Where r2 is the radial distance between any position in the formation and the casing of the second well; B r2,z is the intensity of the alternating induced magnetic field at a radial distance r2 and a vertical distance z=0 from the casing of the second well; σ c is the conductivity of the casing of the second wellbore; S c is the cross-sectional area of ​​the casing of the second well; E r1,z is the electric field strength at the current dividing point.

[0041] In the second aspect, the present application provides an adjacent well tubular excitation system, the system comprising: a first drilling well, a second drilling well, a ground power supply device, a surface leakage current system and a control device for the first drilling well; wherein the first drilling well is a positive drilling well, the first drilling well includes a downhole leakage current system, the second drilling well contains casing or drill pipe, and the ground power supply device is respectively connected to the downhole leakage current system and the surface leakage current system; the system is used to execute the method described in any one of the first aspects above.

[0042] In a third aspect, the present application further provides a control device, the control device comprising:

[0043] An electric field determination module, used to determine the electric field intensity of the current demarcation point on the casing of the second well according to the surrounding formation information of the first well and the distance between the first well and the second well;

[0044] A magnetic field determination module, used to determine the alternating induced magnetic field around the bushing induced by the current flowing on the bushing according to the electric field strength of the current demarcation point;

[0045] A control module is used to control the drilling trajectory of the first well by using the alternating induced magnetic field as a signal source.

[0046] In a fourth aspect, the present application further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes any of the methods described in the first aspect.

[0047] The adjacent well pipe column excitation method provided by the present application applies the potential generated by the ground power supply device to the formation through the downhole leakage system and the surface leakage system in the first drilling well, so that the potential generates an alternating current on the casing of the second drilling well through the formation; the first drilling well is a positive drilling well; the second drilling well includes a casing; the alternating current flows up and down at the current demarcation point of the casing of the second drilling well; the electric field strength in different media is calculated according to the drilling fluid information in the positive drilling well, the spacing between adjacent wells, and the surrounding formation information, and the electric field strength at the position of the current demarcation point of the second drilling well can be determined; according to the electric field strength, the alternating induced magnetic field excited by the alternating current flowing on the casing can be determined. The alternating induced magnetic field is detected in the probe of the first drilling well, providing a signal source for the refined control of the borehole trajectory of the positive drilling well, and can be applied to the technical fields of anti-collision and connectivity, fish detection, and re-entry of old wells with complex structure wells with rescue wells, horizontal wells, and cluster wells as basic features. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0049] Figure 1 A flow chart of an adjacent well string excitation method provided in this application;

[0050] Figure 2 The overall schematic diagram of the excitation system provided for this application;

[0051] Figure 3 A schematic cross-sectional view of the insulated cable provided for this application;

[0052] Figure 4 A schematic diagram of the structural composition of the insulation assembly provided for this application;

[0053] Figure 5 A schematic diagram of the structure of a tubular rigid downhole leakage short joint provided in this application;

[0054] Figure 6 A schematic diagram of the structure of the underground leakage system provided in this application;

[0055] Figure 7 A schematic diagram of the structural composition of the surface leakage system provided for this application;

[0056] Figure 8 A schematic diagram of the adjacent well string excitation method provided in this application;

[0057] Fig. 9 A schematic diagram of the structural composition of a control device provided in this application.

[0058] Description of reference numerals:

[0059] 1. Ground power supply device; 2. First drilling; 3. Second drilling; 4. Casing; 5. Conductive battery; 6. Second insulated cable; 7. First insulated cable; 8. First insulating assembly; 81. Insulating short section; 82. Bridle; 83. Torpedo quick plug; 84. Locker; 9. Downhole leakage short section; 10. Second insulating assembly; 11. Surface leakage short section; 12. Current demarcation point; 13. Downstream current; 14. Alternating induced magnetic field; 15. Soft copper stranded wire; 16. Insulating layer; 17. Semi-conductive filling layer; 18. Inner armored steel wire; 19. Outer armored steel wire; 20. Outer insulating layer.

[0060] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0061] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0062] Figure 1 This is a flow chart of a method for exciting a pipe string in an adjacent well provided in this application. In specific implementation, the method includes the following steps:

[0063] S101: The ground power supply device applies electric potential to the underground leakage system and the surface leakage system of the first drilling well respectively; wherein the applied electric potential generates an alternating current flowing up and down at the current dividing point of the casing of the second drilling well through the formation, and the alternating current excites an alternating induced magnetic field around the casing.

[0064] The first wellbore is a well being drilled; the second wellbore is a well that has been drilled (a well containing casing), or a well being drilled that contains casing.

[0065] Reference Figure 2 , the potential generated by the ground power supply device 1 can be applied to the formation through the downhole leakage system in the first wellbore 2, and the potential in the formation can generate an alternating current on the casing 4 of the second wellbore 3. The first wellbore 2 can be a drilling well, which does not contain casing or drill pipe, and the second wellbore 3 can be a drilled well, and the second wellbore 3 can also be a drilling well, which contains casing or drill pipe.

[0066] Optionally, in order to generate a sufficient electromagnetic field to penetrate the formation and affect the measuring equipment in the adjacent well, the ground power supply device 1 can apply a high potential to ensure the strength and penetration of the electromagnetic signal. In order to match the high potential, the ground power supply device 1 can apply a high voltage to further enhance the strength of the electromagnetic field, so that the signal can propagate farther and more clearly in the underground medium. The ground power supply device 1 can apply a low-frequency square wave voltage to ensure the slowness of the signal change and the smoothness of the waveform. For example, the square wave voltage is as follows: Figure 2 Schematic diagram of square wave in the upper left center. Low-frequency square wave signals can better adapt to complex underground geological structures and reduce signal distortion, thereby providing more accurate and reliable measurement results. The ground power supply device 1 can significantly increase the strength and penetration of the electromagnetic field by increasing power, so that the signal can cover the target area more effectively. Due to the high voltage and low frequency design, the changes in electromagnetic signals in the underground medium can be accurately measured and recorded at a longer distance.

[0067] In the complex geological structure underground, too fast signal changes may cause signal distortion or attenuation during propagation, while low-frequency square wave signals can ensure smoother signal propagation. Square wave signals contain more high-order harmonic components, and compared with pure sine waves, square waves have more frequency components in the spectrum. This enables square waves to provide stronger signal components when penetrating underground media, thereby enhancing signal penetration.

[0068] In some embodiments, a downhole leakage current system may include a first insulating cable, a first insulating component and a downhole leakage current sub; applying the electric potential generated by a ground power supply device to the formation via the downhole leakage current system in a first wellbore may include: transmitting the electric potential generated by the ground power supply device to the downhole leakage current sub via the first insulating cable and the first insulating component in sequence; and applying the electric potential to the formation using the downhole leakage current sub.

[0069] By transmitting the electric potential generated by the ground power supply device to the underground leakage short joint via the first insulating cable and the first insulating component in sequence, and using the underground leakage short joint to apply the electric potential to the formation, on the one hand, a foundation is laid for forming a current loop, and on the other hand, the first insulating cable and the first insulating component can prevent the current on the underground leakage short joint from flowing axially on the insulating cable and the insulating component to generate an axial induced magnetic field when the current loop is subsequently formed.

[0070] Reference Figure 2 The downhole leakage current system may include a first insulating cable 7, a first insulating assembly 8 and a downhole leakage current short section 9. Figure 3The first insulated cable 7 can be a 7-core cable, and the first insulated cable 7 can be soft copper stranded wire 15, insulating layer 16, semi-conductive filling layer 17, inner armored steel wire 18, outer armored steel wire 19 and outer insulating layer 20 from inside to outside. The first insulated cable 7 can withstand large tension and prevent the current from flowing axially on the cable to generate a secondary induced magnetic field to interfere with the measurement results of the downhole probe. It should be noted that all the insulated cables involved in this application include an electromagnetic shielding layer.

[0071] In some embodiments, the first insulating assembly may include an insulating nipple, a bridle, a torpedo quick plug, and an insulating locker. The insulating nipple, the bridle, the torpedo quick plug, and the insulating locker may be sequentially connected to form the first insulating assembly.

[0072] Reference Figure 4 , the first insulating component 8 may include an insulating short section 81, a bridle 82, a torpedo quick plug 83 and a locker 84. The insulating short section 81, the bridle 82, the torpedo quick plug 83 and the insulating locker 84 may be connected in sequence to form the first insulating component 8. Insulating short section 81. The insulating short section 81 has good electrical properties, sufficient mechanical strength and stability, can withstand the voltage and current during normal operation of the equipment, can ensure that no corona, flashover and other phenomena occur, and can withstand vibration and impact during operation. The insulating short section 81 has good aging resistance and can operate stably under different environmental conditions, including high temperature, low temperature, humidity, salt spray, chemical corrosion and other environmental factors. The torpedo quick plug 83 facilitates the connection of the first insulating cable 7 with the cable winch, which can improve the installation efficiency. The first insulating component 8 facilitates the connection of the downhole leakage short section 9 and the downhole probe with the first insulating cable 7, which can avoid the current flowing axially on the first insulating cable 7 to generate a secondary induced magnetic field to interfere with the measurement results of the downhole probe.

[0073] In some embodiments, the downhole leakage sub comprises a rigid tubular leakage sub.

[0074] The underground leakage short joint 9 may include a rigid tubular leakage short joint. Figure 5 The underground leakage short section 9 can be a rigid tubular leakage short section with high temperature resistance and pressure resistance of more than 1000V, and both ends are threadedly connected with the insulating component; the rigid tubular leakage short section has high conductivity and corrosion resistance, can output a volt-level AC signal and is easy to install and lower into the drilling fluid of the first drilling well 2. The rigid electrode is easy to install and lower into the well.

[0075] In some embodiments, one end of the first insulating cable can be connected to the upper part of the downhole leakage short section through a torpedo quick plug in the first insulating assembly, and the other end can be connected to the cable winch through a torpedo quick plug.

[0076] Reference Figure 6 One end of the first insulating cable 7 can be connected to the upper part of the downhole leakage short section 9 through the torpedo quick plug 83 in the first insulating assembly 8, and the other end can be connected to the cable winch through the torpedo quick plug. The cable winch can be connected to the ground power supply device 1 and lowered into the first drilling well 2. The cable winch can facilitate the storage and use of the cable, the torpedo quick plug can facilitate the connection of the cable to the cable winch, and improve the installation efficiency. The insulating assembly facilitates the connection of the downhole leakage short section and the downhole probe with the insulating cable, and can also prevent the current from flowing axially on the cable to generate a secondary induced magnetic field that interferes with the measurement result of the downhole probe.

[0077] In some embodiments, the surface power supply device may apply an electric potential to the formation via a downhole leakage sub to generate a low-frequency square wave alternating current on the casing of the second wellbore.

[0078] The ground power supply device 1 can provide an alternating voltage range of 0 to 1000V and an alternating frequency of 0.5 to 5Hz. The electric potential provided by the ground power supply device 1 can generate a low-frequency square wave alternating voltage. The generated low-frequency square wave alternating voltage has the characteristics of stable signal, high power and low frequency, which can improve the measurement accuracy, help to distinguish the interfering magnetic field, and thus ensure the detection quality of weaker magnetic field signals. The ground power supply device 1 can transmit the electric potential to the downhole leakage short section 9 via the cable winch, the first insulating cable 7 and the first insulating component 8 in sequence. The electric potential can be applied to the formation via the downhole leakage short section 9 in the drilling fluid of the first drilling well 2, and a low-frequency square wave alternating current is generated on the casing 4 of the second drilling well 3.

[0079] The ground power supply device applies an electric potential to the underground leakage system on the one hand, and also applies an electric potential to the surface leakage system on the other hand, generating an electric potential difference to produce a current loop.

[0080] The alternating current in the current loop can flow up and down at the current dividing point 12 of the casing 4 of the second drilling well 3 to generate an alternating induced magnetic field.

[0081] In some embodiments, the surface leakage system includes a second insulating cable, a second insulating assembly and a surface leakage short section; the method may also include: transmitting the electric potential generated by the ground power supply device to the surface leakage short section via the second insulating cable and the second insulating assembly.

[0082] By transmitting the electric potential generated by the ground power supply device to the surface leakage short joint via the second insulating cable, a foundation is laid for forming a current loop. The use of the second insulating cable and the second insulating component can prevent the axial flow of current on the surface leakage short joint from generating an axial induced magnetic field when the current loop is formed.

[0083] Reference Figure 2The surface leakage system may include a second insulating cable 6, a second insulating assembly 10 and a surface leakage short section 11. The second insulating cable 6 may be a 7-core cable, and the second insulating cable 6 may be a soft copper stranded wire 15, an insulating layer 16, a semi-conductive filling layer 17, an inner armored steel wire 18, an outer armored steel wire 19 and an outer insulating layer 20 from the inside to the outside. The second insulating cable 6 can withstand a large tensile force and prevent the current from flowing axially on the cable to generate a secondary induced magnetic field that interferes with the measurement results of the downhole probe. The surface leakage short section 11 can be lowered into the conductive battery 5. Refer to Figure 7 One end of the second insulated cable 6 can be connected to the cable winch by a torpedo quick plug, and the other end can be connected to the surface leakage short section 11 by a wire hinge. The cable winch can be connected to the ground power supply device 1. The ground power supply device 1 can sequentially transmit the generated potential to the surface leakage short section 11 in the conductive battery 5 via the cable winch and the second insulated cable 6.

[0084] In some embodiments, the current demarcation point 12 is a point on the casing of the second wellbore that is radially opposite to the downhole leakage short section 9 in the downhole leakage system of the first wellbore.

[0085] By transmitting the alternating current on the casing of the second well to the surface leakage short joint in the surface leakage system, a current loop is formed. The alternating current in the current loop can flow up and down at the current dividing point on the casing to generate an alternating induced magnetic field.

[0086] Reference Figure 2 and Figure 8 , the current demarcation point 12 can be the radially opposite point of the downhole leakage short section 9 in the downhole leakage system of the first drilling well 2 on the casing 4 of the second drilling well 3. After the divergent electric potential in the formation is gathered on the casing 4 of the second drilling well 3, it can reach the surface leakage short section 11 in the conductive battery 5 through the electric potential streamline, thereby forming a current loop. Under the condition of forming a current loop, the downhole leakage short section 9 can be gathered on the casing 4 of the second drilling well 3 through the drilling fluid and the formation of the first drilling well 2, and flow up and down at the current demarcation point 12 on the casing 4 to generate an alternating induced magnetic field 14. The magnetic induction intensity curve 13' of the alternating induced magnetic field 14 around the casing 4 can be obtained by taking values ​​on the path passing through the downhole leakage short section 9 and parallel to the casing 4, wherein the magnetic induction intensity curve 13' represents the intensity distribution schematic diagram of the casing 4 below the current demarcation point 12 on the longitudinal section.

[0087] S102: The control device determines the electric field intensity of the current demarcation point on the casing of the second well according to the surrounding formation information of the first well and the distance between adjacent wells of the first well and the second well.

[0088] In some embodiments, the radius of the drilling fluid column of the first well can be obtained; the weight factor of the drilling fluid in the first well, the potential of the downhole leakage short joint and the potential of the drilling fluid in the first well can be calculated; the weight factor of the formation and the potential of the formation can be calculated; and then the electric field strength at any position in the formation can be calculated using the following formula.

[0089]

[0090] Where r1 is the radial distance between a target position in the formation and the downhole leakage short joint in the first drilling well; is the electric field intensity at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint in the first drilling well; r f is the radius of the drilling fluid column in the first well; ρ1 is the weight factor of the drilling fluid in the first well; ρ2 is the weight factor of the formation; A is the potential of the downhole leakage short joint in the first well at a radial distance r1 and a vertical distance z=0; B is the potential of the drilling fluid in the first well at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint in the first well; C is the potential of the formation at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint in the first well.

[0091] The electric field strength at any position can be calculated by the weight factor of the drilling fluid in the first drilling, the potential of the downhole leakage short joint, the potential of the drilling fluid in the first drilling, the weight factor of the formation and the potential of the formation, and the radial distance of any position from the leakage short joint.

[0092] Therefore, substituting the distance between the casing and the leakage short joint (which can be replaced by the distance between adjacent wells) into r1 in the above formula, the electric field intensity at the current demarcation point of the casing can be obtained:

[0093] Specifically, according to the drilling data of the first well 2, the radius of the drilling fluid column of the first well 2 can be obtained. According to the alternating voltage, the weight factor of the drilling fluid in the first well 2 and the weight factor of the formation can be calculated. Based on the underground drilling device, the potential of the downhole leakage short section 9, the potential of the drilling fluid in the first well 2 and the potential of the formation can be obtained. When the radial distance between a certain point in the formation and the downhole leakage short section 9 in the first well 2 is less than or equal to the radius of the drilling fluid column in the first well 2, the weight factor of the drilling fluid in the first well 2, the potential of the downhole leakage short section 9 and the potential of the drilling fluid in the first well 2 can be used to calculate the electric field strength of any point in the formation. When the radial distance between a certain point in the formation and the downhole leakage short section 9 in the first well 2 is greater than the radius of the drilling fluid column in the first well 2, the weight factor of the formation and the potential of the formation can be used to directly calculate the electric field strength of this point in the formation. According to the weight factor of the drilling fluid in the first well 2, the potential of the downhole leakage short joint 9, the potential of the drilling fluid in the first well 2, the weight factor of the formation and the potential of the formation, the electric field intensity at any position in the formation can be calculated using the following formula:

[0094]

[0095] Wherein, r1 is the radial distance between a certain position in the formation and the downhole leakage short joint 9 in the first well 2. When calculating the electric field strength at the casing current demarcation point, the radial distance r1 is the radial distance between the current demarcation point and the leakage short joint 9. is the electric field intensity at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint 9 in the first drilling well 2; r f is the radius of the drilling fluid column in the first well 2; ρ1 is the weight factor of the drilling fluid in the first well 2; ρ2 is the weight factor of the formation; A is the potential of the downhole leakage short section 9 in the first well 2 at a radial distance r1 and a vertical distance z=0; B is the potential of the drilling fluid in the first well 2 at a radial distance r1 and a vertical distance z=0 from the downhole leakage short section 9 in the first well 2; C is the potential of the formation at a radial distance r1 and a vertical distance z=0 from the downhole leakage short section 9 in the first well 2.

[0096] In some embodiments, the conductivity of the first drilling fluid and the conductivity of the formation can be obtained; the formula formula and formula The weight factor of the drilling fluid in the first well, the potential of the downhole leakage short joint and the potential of the drilling fluid in the first well are calculated respectively. Where ρ1 is the weight factor of the drilling fluid in the first well; U is the alternating voltage; R is the resistance of the downhole leakage short joint (which can be measured in advance), σ f is the conductivity of the drilling fluid in the first well; σ eis the conductivity of the formation; r1 is the radial distance between a point in the formation and the downhole leakage short joint in the first drilling well; r f is the radius of the drilling fluid column in the first well; A is the potential of the downhole leakage short joint in the first well at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint in the first well; B is the potential of the drilling fluid in the first well at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint in the first well; K0(·) is a zero-order second-kind deformed Bessel function; K1(·) is a first-order second-kind deformed Bessel function; J0(·) is a zero-order first-kind deformed Bessel function; J1(·) is a first-order first-kind deformed Bessel function.

[0097] The weight factor of the drilling fluid in the first well, the potential of the downhole leakage short joint and the potential of the drilling fluid in the first well are calculated by the conductivity of the drilling fluid in the first well and the conductivity of the formation, which lays a data foundation for calculating the electric field strength at any position in the formation.

[0098] When the radial distance between a certain point in the formation and the downhole leakage short sub 9 in the first well 2 is less than or equal to the radius of the drilling fluid column in the first well 2, the weight factor of the drilling fluid in the first well 2, the potential of the downhole leakage short sub 9 and the potential of the drilling fluid in the first well 2 can be used to calculate the electric field strength of this point in the formation. According to the drilling data of the first well 2, the conductivity of the drilling fluid in the first well 2 and the conductivity of the formation can be obtained. Specifically, the following formulas can be used to respectively calculate the weight factor of the drilling fluid in the first well 2, the potential of the downhole leakage short sub 9 at this point in the formation and the potential of the drilling fluid in the first well 2 at this point in the formation, and then calculate the electric field strength of this point in the formation.

[0099]

[0100] Where ρ1 is the drilling fluid weight factor of the first well 2; U is the alternating voltage; R is the resistance of the downhole leakage short joint; σ f is the conductivity of the drilling fluid in the first well 2; σ e is the conductivity of the formation; r1 is the radial distance between a point in the formation and the downhole leakage short joint in the first drilling well 2; r f is the radius of the drilling fluid column in the first well 2; A is the potential of the downhole leakage short joint in the first well 2 at a radial distance r1 and a vertical distance z=0; B is the potential of the drilling fluid in the first well 2 at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint in the first well 2; K0(·) is a zero-order second-kind deformed Bessel function; K1(·) is a first-order second-kind deformed Bessel function; J0(·) is a zero-order first-kind deformed Bessel function; J1(·) is a first-order first-kind deformed Bessel function.

[0101] Among them, the zero-order second-kind deformed Bessel function, which can be expressed as K0(x), is a special form of the Bessel function. The zero-order second-kind deformed Bessel function K0(x) is an infinite series or integral expression that satisfies specific conditions and can be calculated by numerical methods or specific mathematical formulas. K0(x) has a singular point at x=0, so special treatment is required. K0(x) gradually decreases as x increases and tends to 0. K0(x) has a specific asymptotic expression, and when x tends to infinity, its value can be approximately expressed as the product of a constant and the negative exponential power of x. K0(λr f ) can describe the electromagnetic field distribution in the drilling fluid of the first well 2.

[0102] The first-order second-kind deformed Bessel function, which can be expressed as K1(x), is a special form of the Bessel function. The first-order second-kind deformed Bessel function K1(x) is a solution to the Bessel equation. When the order of the equation n=1, the corresponding solution is K1(x). K1(x) is undefined at x=0 because when x=0, the solution of the Bessel equation tends to infinity. K1(x) exhibits oscillatory behavior as x increases and gradually tends to 0. K1(x) has a specific recursive relationship and orthogonality, K1(λr f ) can describe the electromagnetic field distribution in the drilling fluid of the first well 2.

[0103] The zero-order first-kind deformed Bessel function, which can be expressed as J0(x), is a special form of the Bessel function. The zero-order first-kind Bessel function J0(x) is the solution of the Bessel equation when the order is 0. J0(x) can be defined by an infinite series expansion, and the expanded series converges for all real numbers x, so it can be used to calculate the value of J0(x). J0(x) is an even function. When x approaches infinity, the amplitude of J0(x) shows an oscillatory decay. J0(x) has an infinite number of zeros, which are not equally spaced in value, but as x increases, the interval between adjacent zeros gradually approaches π. J0(λr f ) can describe the electromagnetic field distribution in the drilling fluid of the first well 2.

[0104] The first-order first-kind deformed Bessel function, which can be expressed as J1(x), is a special form of the Bessel function. The first-order first-kind Bessel function J1(x) is the solution of the Bessel equation when the order is 1. J1(x) can be defined by an infinite series expansion, and the expanded series is convergent for all real numbers x, so it can be used to calculate the value of J1(x). J1(x) is an odd function. When x approaches infinity, the amplitude of J1(x) shows an oscillatory decay. J1(x) has an infinite number of zeros, which are not equally spaced in value, but as x increases, the interval between adjacent zeros gradually approaches π. J1(λr1) can describe the electromagnetic field distribution at any point in the drilling fluid of the first well 2.

[0105] In some embodiments, the conductivity of the drilling fluid in the first well and the conductivity of the formation can be obtained; the formula and formula Calculate the formation weight factor and formation potential respectively. Where ρ2 is the formation weight factor; U is the alternating voltage; R is the resistance of the underground leakage short joint; σ f is the conductivity of the first drilling fluid; σ e is the conductivity of the formation; r1 is the radial distance between a point in the formation and the downhole leakage short joint in the first drilling well; r f is the radius of the drilling fluid column in the first well; C is the potential of the formation at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint in the first well; K0(·) is a zero-order second-kind deformed Bessel function; K1(·) is a first-order second-kind deformed Bessel function; J0(·) is a zero-order first-kind deformed Bessel function; J1(·) is a first-order first-kind deformed Bessel function.

[0106] The weight factor and the electric potential of the formation are calculated by the conductivity of the drilling fluid of the first well and the conductivity of the formation, which lays a data foundation for calculating the electric field strength at multiple locations in the formation.

[0107] When the radial distance between a certain point in the formation and the downhole leakage short joint 9 in the first well 2 is greater than the radius of the drilling fluid column in the first well 2, the electric field strength of the point in the formation can be directly calculated using the weight factor of the formation and the electric potential of the formation. According to the drilling data of the first well 2, the conductivity of the drilling fluid of the first well 2 and the conductivity of the formation can be obtained. Specifically, the following formulas can be used to respectively calculate the weight factor of the formation and the electric potential of the point in the formation, and then calculate the electric field strength of the point in the formation.

[0108]

[0109] Where ρ2 is the formation weight factor; U is the alternating voltage; R is the resistance of the downhole leakage short joint; σf is the conductivity of the drilling fluid in the first well 2; σ e is the conductivity of the formation; r1 is the radial distance between a point in the formation and the downhole leakage short joint 9 in the first well 2; r f is the radius of the drilling fluid column in the first well 2; C is the potential of the formation at a radial distance r1 and a vertical distance z=0 from the downhole leakage short section 9 in the first well 2; K0(·) is a zero-order second-kind deformed Bessel function; K1(·) is a first-order second-kind deformed Bessel function; J0(·) is a zero-order first-kind deformed Bessel function; J1(·) is a first-order first-kind deformed Bessel function.

[0110] In summary, the electric field strength at any relative position to the leakage short joint in the radial direction of the leakage short joint can be calculated according to the radius of the drilling fluid column, the formation conductivity, and the well fluid conductivity. In the present application scheme, it is necessary to calculate the electric field strength at the current demarcation point on the casing in the second drilling. Therefore, it is necessary to input the radial distance between the casing and the leakage short joint into the above formula to obtain the electric field strength at the current demarcation point.

[0111] S103: The control device determines the alternating induced magnetic field around the bushing induced by the current flowing on the bushing according to the electric field strength at the current demarcation point.

[0112] In some embodiments, the predetermined conductivity and cross-sectional area of ​​the casing of the second well can be obtained; according to the electric field strength at the current demarcation point, the conductivity and cross-sectional area of ​​the casing of the second well, the formula Calculate the alternating induced magnetic field at this point. Where r2 is the radial distance between any point in the formation and the casing of the second well; is the magnetic induction intensity at a radial distance r2 from the casing of the second well and a vertical distance z=0; σ c is the conductivity of the casing of the second well; S c is the cross-sectional area of ​​the casing of the second wellbore; The electric field strength at the current dividing point of the casing of the second drilling well.

[0113] Based on the electric field strength at the current demarcation point, the conductivity and the cross-sectional area of ​​the casing of the second wellbore, the alternating induced magnetic field generated at the current demarcation point can be determined.

[0114] In summary, the strength of the alternating induced magnetic field at any position away from the current demarcation point of the second drilling well can be determined by the above method. Therefore, the relative position of the second drilling detection probe can be determined according to the strength of the detected alternating induced magnetic field during drilling.

[0115] S104, the control device uses the alternating induced magnetic field as a signal source to control the drilling trajectory of the first drilling well.

[0116] A probe for detecting the alternating induced magnetic field is arranged in the first well 2 to detect the magnetic field strength at different positions below the well being drilled.

[0117] In one method, the magnetic induction intensity at different positions can be calculated in advance through the above-mentioned alternating induced magnetic field. Different magnetic induction intensities correspond to different position points. The trajectory is controlled by detecting the magnetic induction intensity through a probe.

[0118] In one method, the relative distance, relative orientation, relative well deviation, and other information between the probe of the probe tube in the first drilling well 2 and the preset target point can be reversely calculated based on the detected alternating induced magnetic field intensity. According to the relative distance, relative orientation, relative well deviation, and other information between the probe in the first drilling well 2 and the preset target point, the borehole trajectory of the first drilling well 2 can be further determined according to the drilling requirements. If the detected borehole trajectory of the first drilling well 2 deviates from the expected borehole trajectory, the control device can adjust the direction of the drill bit in the first drilling well 2 to achieve precise control of the borehole trajectory of the first drilling well 2. By detecting the alternating induced magnetic field 15 around the casing 4, the magnetic field distribution and drill bit position of various complex downhole environments (including high temperature, high pressure, high sulfur content, and other harsh conditions) can be monitored in real time to ensure the safety and accuracy of the drilling operation, thereby more effectively exploiting oil and gas resources and improving the recovery rate. In addition, after using the probe to detect the alternating induced magnetic field around the casing, it can also help further solve the problems of excitation detection, connectivity, and anti-collision technology for directional drilling of complex well structures, as well as the sealing of old wells and the construction of gas storage facilities for storing natural gas and hydrogen.

[0119] The adjacent well pipe column excitation method provided in the embodiment of this specification can apply the potential generated by the ground power supply device to the formation through the downhole leakage system in the first drilling well, so that the potential can generate an alternating current on the casing of the second drilling well through the formation; the first drilling well is a drilling well; the second drilling well is a drilling well that has been drilled or contains casing or drill pipe; the alternating current on the casing of the second drilling well is transmitted to the surface leakage system to form a current loop; the alternating current in the current loop flows up and down at the current dividing point of the casing of the second drilling well; the electric field strength at multiple positions in the formation is obtained; according to the electric field strength, the alternating induced magnetic field excited by the alternating current flowing on the casing is determined. Compared with the existing method, the embodiment of this specification can form an alternating induced magnetic field on the casing of the adjacent well under the condition of forming a current loop, and then the wellbore position information of the drilling well can be determined according to the generated alternating induced magnetic field, which can provide a signal source for the refined control of the wellbore trajectory of the drilling well.

[0120] Based on the above-mentioned adjacent well string excitation method, this specification also proposes an embodiment of a control device. Fig. 9 As shown, the control device 900 may specifically include the following modules:

[0121] An electric field determination module 901 is used to determine the electric field intensity of the current demarcation point on the casing of the second well according to the surrounding formation information of the first well and the distance between the first well and the second well;

[0122] A magnetic field determination module 902 is used to determine the alternating induced magnetic field around the casing induced by the current flowing on the casing according to the electric field strength of the current demarcation point;

[0123] The control module 903 is used to control the drilling trajectory of the first drilling by using the alternating induced magnetic field as a signal source.

[0124] The control device provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and this embodiment will not be described in detail here.

[0125] It should be noted that the units, devices or modules described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. For the convenience of description, the above devices are described separately by functions divided into various modules. Of course, when implementing this specification, the functions of each module can be implemented in the same or more software and / or hardware, or the modules that implement the same function can be implemented by a combination of multiple sub-modules or sub-units. The device embodiments described above are only schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0126] The embodiment of the present specification also provides an electronic device, including a processor and a memory for storing instructions executable by the processor. The electronic device may be a physical device of a first drilling control device.

[0127] Optionally, the device further includes a communication component, wherein the processor, the memory and the communication component are connected via a bus.

[0128] In a specific implementation process, at least one processor executes computer-executable instructions stored in a memory, so that at least one processor executes the above method.

[0129] The specific implementation process of the processor can be found in the above method embodiment, and its implementation principle and technical effect are similar, so this embodiment will not be repeated here.

[0130] In the above embodiments, it should be understood that the processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), etc. A general-purpose processor may be a microprocessor or any conventional processor. The steps of the method disclosed in the invention may be directly implemented as being executed by a hardware processor, or may be executed by a combination of hardware and software modules in the processor.

[0131] The memory may include a high-speed memory (Random Access Memory, RAM), and may also include a non-volatile memory (Non-volatile Memory, NVM), such as at least one disk memory.

[0132] The bus may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the bus in the drawings of the present application is not limited to only one bus or one type of bus.

[0133] The present application also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0134] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the above method is implemented.

[0135] The above-mentioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special-purpose computer.

[0136] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (Application Specific Integrated Circuits, referred to as: ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0137] The division of units is only a logical function division, and there may be other divisions in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0138] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0139] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0140] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0141] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, disk or optical disk and other media that can store program codes.

[0142] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for exciting a pipe string in an adjacent well, characterized in that: Applied to the adjacent well pipe column excitation system, the system comprises: a first drilling well, a second drilling well, a ground power supply device, a surface leakage system and a control device for the first drilling well; wherein the first drilling well is a positive drilling well, the first drilling well comprises a downhole leakage system, the second drilling well comprises a casing, and the ground power supply device is respectively connected to the downhole leakage system and the surface leakage system; the method comprises: The ground power supply device applies electric potential to the downhole leakage system and the surface leakage system of the first well respectively; wherein the applied electric potential generates an alternating current flowing up and down at the current boundary point of the casing of the second well via the stratum, and the alternating current excites an alternating induced magnetic field around the casing; The control device determines the electric field intensity at the current demarcation point on the casing in the second well according to the surrounding formation information of the first well and the distance between the first well and the second well; The control device determines the alternating induced magnetic field around the bushing excited by the current flowing on the bushing according to the electric field strength at the current demarcation point; The control device uses the alternating induced magnetic field as a signal source to control the drilling trajectory of the first well.

2. The method according to claim 1, characterized in that: The underground leakage current system comprises a first insulating cable, a first insulating component and an underground leakage current short joint; The surface power supply device applies an electric potential to the downhole leakage current system of the first drilling well, comprising: the electric potential generated by the surface power supply device is sequentially transmitted to the downhole leakage current short joint via the first insulating cable and the first insulating assembly, so as to apply the electric potential to the formation using the downhole leakage current short joint; The current demarcation point is a point on the casing of the second wellbore that is radially opposite to the downhole leakage short joint of the downhole leakage system; and / or; The applied potential is a low-frequency square wave voltage; and / or; The surface leakage system comprises a second insulating cable, a second insulating component and a surface leakage short section.

3. The method according to claim 2, characterized in that: Determining the electric field intensity of the current demarcation point on the casing of the second well according to the surrounding formation information of the first well and the distance between the first well and the second well comprises: Obtaining the radius of the drilling fluid column of the first well; Determining a weight factor of the drilling fluid in the first well, an electric potential of the downhole leakage sub, and an electric potential of the drilling fluid in the first well; Determine the weight factor of the formation and the electrical potential of the formation; The electric field strength at any position is calculated using the following formula according to the weight factor of the drilling fluid in the first well, the potential of the downhole leakage sub, the potential of the drilling fluid in the first well, the weight factor of the formation and the potential of the formation: Where r1 is the radial distance between any position in the formation and the downhole leakage short joint; E r1,z is the electric field strength at a radial distance r1 and a vertical distance z=0 from the underground leakage short joint; r f is the radius of the drilling fluid column in the first well; ρ1 is the weight factor of the drilling fluid in the first well; ρ2 is the weight factor of the formation; A is the potential of the downhole leakage short joint at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint; B is the potential of the drilling fluid in the first well at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint; C is the potential of the formation at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint; Substituting the distance between adjacent wells into r1 in the above formula, the electric field intensity at the current demarcation point is obtained.

4. The method according to claim 3, characterized in that: The determining of the weight factor of the drilling fluid in the first drilling well, the potential of the downhole leakage sub, and the potential of the drilling fluid in the first drilling well comprises: Obtaining the conductivity of the first drilling fluid and the conductivity of the formation; The weight factor of the drilling fluid in the first well, the potential of the downhole leakage sub, and the potential of the drilling fluid in the first well are calculated respectively using the following formulas: Wherein, ρ1 is the drilling fluid weight factor of the first drilling well; U is the alternating voltage; R is the resistance of the downhole leakage short joint; σ f is the conductivity of the drilling fluid in the first well; σ e is the conductivity of the formation; r1 is the radial distance between the target position in the formation and the downhole leakage short joint in the first drilling well; r f is the radius of the drilling fluid column in the first drilling well; A is the potential of the downhole leakage short joint at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint; B is the potential of the drilling fluid in the first drilling well at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint; K0(·) is a zero-order second-kind deformed Bessel function; K1(·) is a first-order second-kind deformed Bessel function; J0(·) is a zero-order first-kind deformed Bessel function; J1(·) is a first-order first-kind deformed Bessel function.

5. The method according to claim 3, characterized in that: The step of determining the weight factor of the formation and the electric potential of the formation comprises: Obtaining the conductivity of the drilling fluid and the conductivity of the formation in the first drilling well; The weight factor of the formation and the electric potential of the formation are calculated respectively using the following formulas: Wherein, ρ2 is the weight factor of the formation; U is the alternating voltage; R is the resistance of the downhole leakage short joint; σ f is the conductivity of the first drilling fluid; σ e is the conductivity of the formation; r1 is the radial distance between the target position in the formation and the downhole leakage short joint; r f is the radius of the drilling fluid column in the first drilling well; C is the potential of the formation at a radial distance r1 and a vertical distance z=0 from the downhole leakage short joint; K0(·) is a zero-order second-kind deformed Bessel function; K1(·) is a first-order second-kind deformed Bessel function; J0(·) is a zero-order first-kind deformed Bessel function; J1(·) is a first-order first-kind deformed Bessel function.

6. The method according to claim 1, characterized in that: The step of determining the alternating induced magnetic field around the bushing induced by the current flowing through the bushing according to the electric field strength at the current demarcation point comprises: According to the electric field intensity at the current demarcation point, the conductivity of the casing of the second wellbore and the cross-sectional area, the alternating induced magnetic field excited around the casing is calculated using the following formula: Wherein, r2 is the radial distance between any position in the formation and the casing of the second wellbore; is the intensity of the alternating induced magnetic field at a radial distance r2 and a vertical distance z=0 from the casing of the second well; σ c is the conductivity of the casing of the second wellbore; S c is the cross-sectional area of ​​the casing of the second wellbore; is the electric field strength at the current dividing point.

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