A method for predicting underground magnetic field in rescue wells based on a three-layer resistance network model

Abstract

The embodiments of the present application relate to the field of downhole rescue technology, and in particular to a method for predicting downhole magnetic fields in a rescue well based on a three-layer resistance network model, comprising: defining an effective transmission surface based on the current transmission characteristics of a downhole current injection method, and dividing the current transmission into three transmission layers, namely, a transmitting layer, a convergence layer, and a receiving layer; dividing the metal casing into #imgabs0# segments of equal length to obtain #imgabs1# interception points; constructing a three-layer resistance network model based on the current transmission path of each transmission layer, wherein the three-layer resistance network model includes formation equivalent resistance, metal casing equivalent resistance, and stray equivalent resistance; solving the three-layer resistance network model based on Kirchhoff's law, determining the current of each interception point, and determining the loop voltage of the three-layer resistance network model; based on the Bio-Savart law, combining the current and loop voltage of each interception point, scientifically, accurately, and quickly determining the magnetic field distribution in the downhole space of the rescue well.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of downhole rescue technology, and in particular to a method for predicting downhole magnetic fields in a rescue well based on a three-layer resistance network model. Background Art

[0002] In recent years, with the rapid development of the oil industry and the increasing frequency of oil extraction activities, the issue of engineering safety control during oil extraction has received increasing attention from research teams and companies both domestically and internationally. A blowout accident occurs during the oil or natural gas extraction process, where a pressure imbalance or equipment failure causes a sudden and uncontrolled surge of oil and gas from underground to the surface. The direct economic and human losses caused by this accident are enormous and unacceptable.

[0003] Rescue well technology is an emergency rescue method for dealing with oil and gas field blowout accidents. When a blowout accident occurs, the wellhead of the oil and gas well is out of control and the blowout cannot be directly controlled. Rescue well technology can help control the blowout and reduce losses by drilling or perforating, while also preventing larger-scale accidents.

[0004] As a rescue well technology, well-to-ground current injection has been widely used in recent years. The principle of well-to-ground current injection is to install a specific electrode system in the rescue well to inject a current of a certain intensity. The purpose of current injection is to generate an induced magnetic field through the convergence of the emitted current in the accident well. This magnetic field can be used to determine the location of the accident well, helping to increase the chances of successful plugging in the early stages of a blowout and prevent further deterioration of the blowout.

[0005] However, the effectiveness and accuracy of the borehole current injection method relies on accurate research into the downhole magnetic field distribution. This is particularly true for directional drilling in rescue wells, where accurate magnetic field prediction is crucial for success. In this method, the estimation of the downhole magnetic field relies primarily on the distribution of the convergent current formed by the excitation current on the casing. Based on the Biot-Savart law, the magnitude and flow path of the convergent current can be used to calculate the downhole magnetic field information. Accurately determining the current distribution pattern on the casing or drill pipe of the accident well is a key challenge in magnetic field estimation.

[0006] Currently, the more commonly used methods for determining the current distribution in metal casing of accident wells mainly include the current loss estimation method and the equivalent cylinder model method. The current loss estimation method estimates the current distribution on the casing by analyzing the attenuation of the current along the propagation path caused by partial leakage of current into the surrounding formation during current propagation on the casing. This method is theoretically accurate, but the calculation is complex and is greatly limited by the non-uniformity of formation conductivity. The equivalent cylinder model method simplifies the calculation of the concentrated current on the casing by assuming an equivalent cylinder with the same conductivity characteristics as the actual casing. This method is simple to calculate, but ignores the impact of the actual length and local structure of the casing on the current distribution, and its applicability is limited.

[0007] While both methods can estimate casing current distribution to a certain extent, they fail to fully consider the impact of casing length on downhole magnetic field distribution. Furthermore, given the uneven formation conductivity and complex local casing structure, the current propagation path and attenuation patterns remain unclear. These factors result in low accuracy in estimating the current distribution in the metal casing of the accident well, which in turn leads to inaccurate predictions of the downhole magnetic field in the rescue well, hindering the development of rescue well technology. Summary of the Invention

[0008] In order to solve the above technical problems, the embodiment of the present application proposes a method for predicting the underground magnetic field of a rescue well based on a three-layer resistance network model. Through field circuit analysis, it effectively simulates the actual distribution of the current in the metal casing, breaking through the limitation of the traditional method of assuming infinite length of the metal casing, thereby being able to scientifically, accurately and quickly predict the distribution of the underground magnetic field of the rescue well, providing convenience for subsequent applications such as target well positioning.

[0009] In order to achieve the above-mentioned purpose, the embodiment of the present application proposes a method for predicting the underground magnetic field of a rescue well based on a three-layer resistance network model, including: defining an effective transmission surface based on the current transmission characteristics of the downhole current injection method, and dividing the current transmission into three transmission layers, namely, an emission layer, a convergence layer and a receiving layer; wherein, the emission layer represents the current converged from the emission electrode to the metal casing through different formation routes, the convergence layer represents the current on the metal casing flowing up and down along the pipe, and the receiving layer represents the current flowing back to the grounding electrode through different formation routes; a length of The metal casing is divided into equal lengths Segment, get interception points; based on the current transmission path of each transmission layer, a three-layer resistance network model is constructed, which includes the formation equivalent resistance, metal casing equivalent resistance and stray equivalent resistance; the three-layer resistance network model is solved based on Kirchhoff's law to determine the current of each interception point and the loop voltage of the three-layer resistance network model; based on the Bio-Savart law, the current and loop voltage of each interception point are combined to determine the magnetic field generated by the metal casing at each position in the underground space of the rescue well, and then the magnetic field distribution in the underground space of the rescue well is determined.

[0010] In order to achieve the above-mentioned purpose, the embodiment of the present application also proposes a rescue well downhole magnetic field prediction system based on a three-layer resistance network model, including: a transmission layer division module, a truncation module, a model construction module, a model solution module and a magnetic field calculation module; the transmission layer division module is used to define the effective transmission surface based on the current transmission characteristics of the downhole current injection method, and divide the current transmission into three transmission layers, the three transmission layers are respectively a transmitting layer, a convergence layer and a receiving layer, the transmitting layer represents the current converged from the transmitting electrode to the metal casing through different formation routes, the convergence layer represents the current on the metal casing flowing up and down along the pipe, and the receiving layer represents the current flowing back to the grounding electrode through different formation routes; the truncation module is used to divide the length of The metal casing is divided into equal lengths Segment, get interception points; a model construction module, which is used to construct a three-layer resistance network model based on the current transmission path of each transmission layer. The three-layer resistance network model includes the formation equivalent resistance, the metal casing equivalent resistance and the stray equivalent resistance; a model solving module, which is used to solve the three-layer resistance network model based on Kirchhoff's law, determine the current of each interception point, and determine the loop voltage of the three-layer resistance network model; a magnetic field calculation module, which is used to determine the magnetic field generated by the metal casing at each position in the underground space of the rescue well based on the Bio-Savart law and the current and loop voltage of each interception point, and then determine the magnetic field distribution in the underground space of the rescue well.

[0011] In order to achieve the above-mentioned purpose, an embodiment of the present application also proposes an electronic device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute a method for predicting underground magnetic fields in rescue wells based on a three-layer resistance network model as described above.

[0012] In order to achieve the above-mentioned purpose, an embodiment of the present application also proposes a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it can implement a method for predicting the underground magnetic field of a rescue well based on a three-layer resistance network model as described above.

[0013] This application proposes a method for predicting the downhole magnetic field in rescue wells based on a three-layer resistor network model. This model is constructed through field-path model analysis to predict the downhole magnetic field in the rescue well, effectively simulating the current in the metal casing and the actual distribution of the downhole spatial magnetic field. This method overcomes the limitations of traditional analytical models and can reliably estimate the concentrated current on the metal casing and the distribution of the downhole spatial magnetic field during the well-to-ground current injection method. By dividing the metal casing and the formation medium into equal segments, this application successfully constructs a resistor network, addressing the limitation of the conflicting analytical model's assumption of infinite length for the metal casing and effectively improving the accuracy of downhole magnetic field prediction. By solving the resistor network equations of the three-layer resistor network model, the current and loop voltage at each intercept point are easily solved and the computation speed is fast, thereby improving the speed of downhole magnetic field prediction. Given the complexity of downhole operations, using this application to locate subsequent target wells (rescue wells and accident wells) can significantly save manpower and time costs, effectively meeting the urgency of rescue missions.

[0014] Optionally, after changing the length to The metal casing is divided into equal lengths Segment, get After the cutoff points, The cutoff point is recorded as , ;

[0015] Based on the current transmission paths of each transmission layer, a three-layer resistor network model is constructed, including:

[0016] Assume that the direction of the formation current in the three-layer resistance network model is from the transmitting electrode to the grounding electrode, and the output current of the transmitting electrode is , the emission layer The transmission current of the transmission path is , the first The transmission current of the transmission path is , the receiving layer The transmission current of the transmission path is , the total stray branch current is ;

[0017] Set the emitter electrode to the metal sleeve Cutoff points The equivalent resistance is , the first Cutoff points To Cutoff points The equivalent resistance is , the first Cutoff points The equivalent resistance to the return electrode is , the branch resistance of the stray current flowing through the total equivalent branch is .

[0018] Optionally, the emitter electrode is connected to the metal sleeve. Cutoff points The equivalent resistance , and the first Cutoff points Equivalent resistance to return electrode , are equivalent formation resistances;

[0019] It is expressed by the formula:

[0020] ;

[0021] ;

[0022] in, is the resistivity of the formation, is the conductivity of the formation, and They are the emission layer The length and cross-sectional area of ​​the transmission path segment, is the radius of the metal casing;

[0023] It is expressed by the formula:

[0024] ;

[0025] ;

[0026] in, and The receiving layer The length and cross-sectional area of ​​the transmission path.

[0027] Optionally, the first Cutoff points To Cutoff points The equivalent resistance is the equivalent resistance of the metal casing;

[0028] It is expressed by the formula:

[0029] ;

[0030] ;

[0031] in, is the resistivity of the metal casing, is the conductivity of the metal casing, The first The length of the transmission path is related to the length of the metal sleeve. Segment length equal, The first The cross-sectional area of ​​the transmission path.

[0032] Optionally, the three-layer resistor network model is solved based on Kirchhoff's law to determine the current at each intercept point, including:

[0033] Based on Kirchhoff's law, the sum of all currents entering the intercept point in the three-layer resistor network model is determined to be 0;

[0034] For the emitting electrode, its current satisfies the following relationship:

[0035] ;

[0036] For each intercept point on the metal casing, the current satisfies the following relationship:

[0037] ;

[0038] For the return electrode, since the return electrode is grounded, there is no need to consider the current at the intercept point.

[0039] Optionally, determining a loop voltage of the three-layer resistor network model includes:

[0040] Based on Kirchhoff's law, the sum of all voltages in the circuit loop of the three-layer resistor network model is determined to be 0. The loop voltage of the three-layer resistor network model is divided into three parts: the transmitting and receiving loops of the converged current on each section of the metal casing, and the branch path of the stray current.

[0041] For the emission loop of the converged current on each section of the metal casing, the voltage equation is:

[0042] ;

[0043] ;

[0044] For the receiving loop of the converged current on each section of the metal casing, the voltage equation is:

[0045] ;

[0046] ;

[0047] For stray current flowing through a branch, the voltage equation is:

[0048] .

[0049] Optionally, based on the Bio-Savart law, the magnetic field generated by the metal casing at each position in the underground space of the rescue well is determined in combination with the current and loop voltage at each intercept point, thereby determining the magnetic field distribution in the underground space of the rescue well, including:

[0050] Based on the Bio-Savart law, determine the The metal casing is located at a point in the underground space. The magnetic field generated at is:

[0051] ;

[0052] in, For the The length of the metal casing, is the vacuum permeability, For the Metal casing to The unit vector of the point, For the Metal casing to The distance vector of the point, For the Section metal casing The magnetic field generated by the point;

[0053] The following formula is used to calculate the position of each section of metal casing at a point in the underground space: The vector sum of the magnetic field generated at the point is the sum of the magnetic field at the point where the entire metal casing is located in the downhole space. The magnetic field generated at:

[0054] ;

[0055] in, Indicates that the entire metal casing is The magnetic field generated by the point. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the related technologies, the following is a brief introduction to the drawings required for use in the embodiments of the present application or the description of the related technologies. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0057] Figure 1 This is a flow chart of a method for predicting downhole magnetic field in a rescue well based on a three-layer resistance network model provided in one embodiment of the present application;

[0058] Figure 2 is a schematic diagram of a well-to-ground current injection method provided in one embodiment of the present application;

[0059] Figure 3 This is a distribution line diagram of underground current density when using the well-ground current injection method for underground rescue provided in one embodiment of the present application;

[0060] Figure 4 is a schematic structural diagram of a three-layer resistor network model provided in one embodiment of the present application;

[0061] Figure 5 is a schematic diagram of a magnetic field generated by current on a metal casing provided in one embodiment of the present application;

[0062] Figure 6 1 is a schematic structural diagram of a downhole magnetic field prediction system for a rescue well based on a three-layer resistance network model provided in another embodiment of the present application;

[0063] Figure 7 It is a structural diagram of an electronic device provided in another embodiment of the present application. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, each embodiment of the present application will be described in detail below with reference to the accompanying drawings. However, it will be understood by those skilled in the art that in each embodiment of the present application, many technical details are proposed to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can be implemented. The division of the following embodiments is for convenience of description and should not constitute any limitation on the specific implementation of the present application. The various embodiments can be combined with each other and referenced to each other under the premise of no contradiction.

[0065] In order to solve the problem of insufficient accuracy in the currently proposed downhole magnetic field estimation methods, an embodiment of the present application proposes a method for predicting the downhole magnetic field of a rescue well based on a three-layer resistor network model, which is applied to an electronic device, wherein the electronic device can be a terminal or a server. This embodiment and the following embodiments are all described using a server as an example. The following is a detailed description of the implementation details of the method for predicting the downhole magnetic field of a rescue well based on a three-layer resistor network model proposed in this embodiment. The following content is only the relevant implementation details provided for ease of understanding and is not necessary for the implementation of this solution.

[0066] The specific process of the method for predicting the underground magnetic field of a rescue well based on a three-layer resistance network model proposed in this embodiment can be as follows: Figure 1 Shown, including:

[0067] Step 101: Based on the current transmission characteristics of the downhole current injection method, an effective transmission surface is defined, and the current transmission is divided into three transmission layers, namely, a transmitting layer, a convergence layer, and a receiving layer. The transmitting layer represents the current converged from the transmitting electrode to the metal casing through different formation routes, the convergence layer represents the current on the metal casing flowing up and down along the pipe, and the receiving layer represents the current flowing back to the grounding electrode through different formation routes.

[0068] The specific implementation of the downhole current injection method can be as follows: Figure 2 As shown, the construction of a downhole current injection system requires no manipulation of the target well; rescue operations can be carried out by simply drilling a rescue well within a safe range. The basic principle is that an alternating current is injected into the rescue well via a positive electrode. This current couples with the target well's metal casing or drill pipe and is then conducted through the formation. Due to the high electrical conductivity of the target well's metal casing or drill pipe, the low-frequency current can flow along it, generating a specific magnetic field signal around the target well. This magnetic field signal is detected by an electromagnetic detection unit in the rescue well. Combined with gravity field data and algorithms, the distance and direction between the rescue well and the target well can be determined.

[0069] Figure 3 This is a line diagram of the underground current density distribution when using the well-ground current injection method. The current injection system sends current underground through the transmitting electrode. The current is transmitted through the formation and the casing of the accident well, and ultimately returns to the ground electrode. This application uses a resistance network model to model the equivalent circuit of underground detection.

[0070] The server needs to define the effective transmission surface based on the current transmission characteristics of the downhole current injection method and divide the current transmission into three transmission layers. The three transmission layers are the transmitting layer, the convergence layer, and the receiving layer. The transmitting layer represents the current converging from the transmitting electrode to the metal casing through different formation routes. The convergence layer represents the current flowing up and down the metal casing. The receiving layer represents the current returning to the ground electrode through different formation routes.

[0071] Step 102: The metal casing is divided into equal lengths Segment, get A cutoff point.

[0072] In the specific implementation, the convergence layer, as the middle transmission layer, is the key to the construction of the entire transmission system. Route division, as an important method of field path model, can also be applied to the metal casing of the convergence layer. The server cuts the metal casing into equal lengths segments, each segment is , so we can get A cutoff point.

[0073] In one example, the server will The cutoff point is recorded as , .

[0074] It should be noted that is an integer greater than 2, usually .

[0075] Step 103 : constructing a three-layer resistance network model based on the current transmission paths of each transmission layer. The three-layer resistance network model includes formation equivalent resistance, metal casing equivalent resistance, and stray equivalent resistance.

[0076] In practice, after completing the cutoff point division, the server constructs a three-layer resistance network model (earth-metal casing-earth) based on the current transmission paths of each transmission layer. The equivalent resistance in this three-layer resistance network model includes the formation equivalent resistance, the metal casing equivalent resistance, and the stray equivalent resistance.

[0077] In an example, the specific structure of the three-layer resistor network model can be as follows Figure 4 shown.

[0078] In one example, the focus of building a three-layer resistor network model is to determine the equivalent current and equivalent resistance.

[0079] Assume that the direction of the formation current in the three-layer resistance network model is from the transmitting electrode to the grounding electrode, and the output current of the transmitting electrode is , the emission layer The transmission current of the transmission path is , the first The transmission current of the transmission path is , the receiving layer The transmission current of the transmission path is , the total stray branch current is The units of these equivalent currents are (ampere).

[0080] Set the emitter electrode to the metal sleeve Cutoff points The equivalent resistance is , the first Cutoff points To Cutoff points The equivalent resistance is , the first Cutoff points The equivalent resistance to the return electrode is , the branch resistance of the stray current flowing through the total equivalent branch is The units of these equivalent resistances are (ohm).

[0081] In one example, the emitter electrode is connected to the metal sleeve. Cutoff points The equivalent resistance , and the first Cutoff points Equivalent resistance to return electrode , are equivalent formation resistances.

[0082] It is expressed by the formula:

[0083] ;

[0084] ;

[0085] in, is the resistivity of the formation, in units of , is the conductivity of the formation, in units of , and They are the emission layer The length and cross-sectional area of ​​the transmission path segment, in units of and , is the radius of the metal casing, in units of .

[0086] It should be noted that is an approximate value, approximately The area of ​​the longitudinal section of the metal casing.

[0087] It is expressed by the formula:

[0088] ;

[0089] ;

[0090] Among them, and similar, and The receiving layer The length and cross-sectional area of ​​the transmission path segment, in units of and .

[0091] In one example, the first Cutoff points To Cutoff points The equivalent resistance is the equivalent resistance of the metal casing.

[0092] It is expressed by the formula:

[0093] ;

[0094] ;

[0095] in, is the resistivity of the metal casing, in units of , is the conductivity of the metal casing, and its units are and , The first The length of the segment transmission path in units of , With metal casing Segment length equal, The first The cross-sectional area of ​​the transmission path in units of .

[0096] In one example, because the stray equivalent resistance resides within the ineffective transmission space, its physical meaning can be considered an abstract total field equivalent resistance. Given the differences in test environments, the transmission characteristics of this ineffective transmission space can also vary, making a simple equivalent resistance estimate impossible. To better describe this phenomenon, this embodiment treats the stray equivalent resistance as environmental resistance.

[0097] Step 104 : Solve the three-layer resistor network model based on Kirchhoff's law to determine the current at each intercept point and the loop voltage of the three-layer resistor network model.

[0098] In practice, after constructing the three-layer resistor network model, Kirchhoff's law can be used to solve the model, determining the current at each intercept point and the loop voltage of the three-layer resistor network model. This is because the equivalent circuit of the three-layer resistor network model is a purely resistive circuit.

[0099] For the intercept current, based on Kirchhoff's law, it can be determined that the sum of all currents entering the intercept in the three-layer resistor network model is 0. Therefore, the current relationship of each intercept can be summarized as follows.

[0100] For the emitting electrode, its current satisfies the following relationship: ;

[0101] For each intercept point on the metal casing, the current satisfies the following relationship:

[0102] .

[0103] For the return electrode, since the return electrode is grounded, there is no need to consider the current at the intercept point.

[0104] As for the loop voltage, based on Kirchhoff's law, it can be determined that the sum of all voltages in the circuit loop of the three-layer resistor network model is 0. In this embodiment, the loop voltage of the three-layer resistor network model is divided into three parts, namely the transmitting loop and the receiving loop of the converged current on each section of the metal casing, and the stray current flowing through the branch.

[0105] For the emission loop of the converged current on each section of the metal casing, the voltage equation is:

[0106] ;

[0107] .

[0108] For the receiving loop of the converged current on each section of the metal casing, the voltage equation is:

[0109] ;

[0110] .

[0111] For stray current flowing through a branch, the voltage equation is:

[0112] .

[0113] Based on this, the total circuit equation of the three-layer resistor network model can be written as:

[0114] ;

[0115] ;

[0116] , .

[0117] Step 105 , based on the Bio-Savart law and in combination with the current and loop voltage at each intercept point, the magnetic field generated by the metal casing at each position in the underground space of the rescue well is determined, thereby determining the magnetic field distribution in the underground space of the rescue well.

[0118] In the three-layer resistor network model, the current output by the transmitting electrode converges to the metal casing in the accident well through the transmitting branches of each layer. The casing of the accident well is divided into N sections of equal length metal pipes on the casing. The current distribution on the entire casing is non-uniform. When the length of each segment after equal division is , it can be approximately considered that the current on each section of the metal casing is uniform. Figure 5 This is a schematic diagram of the magnetic field generated by the current on the metal casing. Solving the spatial magnetic field distribution problem is transformed into solving The problem of obtaining the magnetic field information generated by a segment of uniform current line in space.

[0119] Based on the Bio-Savart law, we know that the current source A point in the underground space The magnetic induction intensity generated at and Proportional to arrive The square of the distance between the points is inversely proportional, that is:

[0120] ;

[0121] in, is a current source exist The magnetic field generated by the point, is the vacuum permeability, for arrive The distance vector of the point.

[0122] Based on this, it can be determined that The metal casing is located at a point in the underground space. The magnetic field generated at is:

[0123] ;

[0124] in, For the The length of the metal casing, For the Metal casing to The unit vector of the point, For the Metal casing to The distance vector of the point, For the Section metal casing The magnetic field generated by the point.

[0125] The following formula is used to calculate the position of each section of metal casing at a point in the underground space: The vector sum of the magnetic field generated at the point is the sum of the magnetic field at the point where the entire metal casing is located in the downhole space. The magnetic field generated at:

[0126] ;

[0127] in, Indicates that the entire metal casing is The magnetic field generated by the point.

[0128] At this point, the magnetic field at each position in the underground space of the rescue well can be calculated. By combining the magnetic fields at each position in the underground space of the rescue well, the magnetic field distribution in the underground space of the rescue well can be obtained.

[0129] This embodiment proposes a method for predicting the downhole magnetic field in rescue wells based on a three-layer resistor network model. This model is constructed through field-path model analysis to predict the downhole magnetic field in the rescue well, effectively simulating the current in the metal casing and the actual distribution of the downhole spatial magnetic field. This method overcomes the limitations of traditional analytical models and can reliably estimate the concentrated current on the metal casing and the distribution of the downhole spatial magnetic field during the well-to-ground current injection method. By dividing the metal casing and the formation medium into equal segments, this method successfully constructs a resistor network, addressing the limitation of the conflicting analytical model's assumption of infinite length for the metal casing and effectively improving the accuracy of downhole magnetic field prediction. By solving the resistor network equations of the three-layer resistor network model, the current and loop voltage at each intercept point are easily solved and the computation speed is fast, thereby improving the speed of downhole magnetic field prediction. Given the complexity of downhole operations, using this method to locate subsequent target wells (rescue wells and accident wells) can significantly save labor and time costs, effectively meeting the urgency of rescue missions.

[0130] The steps of the various methods described above are divided for clarity of description only. During implementation, they can be combined into a single step, or some steps can be split into multiple steps. As long as they contain the same logical relationships, they are all within the scope of protection of this application. Adding minor modifications or introducing minor designs to the algorithm or process, but not changing the core design of the algorithm or process, are also within the scope of protection of this application.

[0131] Another embodiment of the present application proposes a rescue well underground magnetic field prediction system based on a three-layer resistance network model. The details of the rescue well underground magnetic field prediction system based on a three-layer resistance network model proposed in this embodiment are described in detail below. The following content is only the implementation details provided for easy understanding and is not necessary for the implementation of this example.

[0132] The specific structure of the downhole magnetic field prediction system for a rescue well based on a three-layer resistance network model proposed in this embodiment can be as follows: Figure 6 As shown, it includes: a transmission layer division module 201, a truncation module 202, a model construction module 203, a model solution module 204 and a magnetic field calculation module 205.

[0133] The transmission layer division module 201 is used to define the effective transmission surface based on the current transmission characteristics of the downhole current injection method, and divide the current transmission into three transmission layers. The three transmission layers are the transmitting layer, the convergence layer and the receiving layer. The transmitting layer represents the current converged from the transmitting electrode to the metal casing through different formation routes. The convergence layer represents the current on the metal casing flowing up and down along the pipe. The receiving layer represents the current flowing back to the grounding electrode through different formation routes.

[0134] The truncation module 202 is used to divide the length The metal casing is divided into equal lengths Segment, get A cutoff point.

[0135] The model building module 203 is used to build a three-layer resistance network model based on the current transmission path of each transmission layer. The three-layer resistance network model includes formation equivalent resistance, metal casing equivalent resistance and stray equivalent resistance.

[0136] The model solving module 204 is used to solve the three-layer resistor network model based on Kirchhoff's law, determine the current of each intercept point, and determine the loop voltage of the three-layer resistor network model.

[0137] The magnetic field calculation module 205 is used to determine the magnetic field generated by the metal casing at each position in the underground space of the rescue well based on the Bio-Savart law and the current and loop voltage of each intercept point, and then determine the magnetic field distribution in the underground space of the rescue well.

[0138] It is worth mentioning that all modules involved in this embodiment are logical modules. In actual applications, a logical unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. In addition, to highlight the innovation of this application, this embodiment does not include units that are not closely related to solving the technical problem proposed by this application. However, this does not mean that other units do not exist in this embodiment.

[0139] It is not difficult to find that this embodiment is a system embodiment corresponding to the above-mentioned method embodiment, and this embodiment can be implemented in conjunction with the above-mentioned method embodiment. The relevant technical details and technical effects mentioned in the above-mentioned method embodiment are still valid in this embodiment, and to reduce repetition, they are not repeated here. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to the above-mentioned method embodiment.

[0140] Another embodiment of the present application provides an electronic device, the specific structure of which can be as follows: Figure 7 As shown, it includes: at least one processor 301; and a memory 302 that is communicatively connected to the at least one processor 301; wherein the memory 302 stores instructions that can be executed by the at least one processor 301, and the instructions are executed by the at least one processor 301 so that the at least one processor 301 can execute a method for predicting the downhole magnetic field of a rescue well based on a three-layer resistance network model as described in the above method embodiment.

[0141] The memory and processor are connected using a bus, which can include any number of interconnected buses and bridges. The bus connects various circuits of one or more processors and memories. The bus can also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits. These are all well known in the art and therefore will not be described further herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be a single component or multiple components, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over a wireless medium via an antenna. Furthermore, the antenna receives data and transmits it to the processor.

[0142] The processor is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory can be used to store data used by the processor when performing operations.

[0143] Another embodiment of the present application provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it can implement a method for predicting the downhole magnetic field of a rescue well based on a three-layer resistance network model as described in the above method embodiment.

[0144] That is, those skilled in the art will understand that all or part of the steps in the above-described method embodiments can be implemented by instructing the relevant hardware through a program. The program is stored in a storage medium and includes a number of instructions for causing a device (such as a microcontroller or chip) or a processor to execute all or part of the steps in the method embodiments described herein. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a mobile hard drive, a read-only memory, a random access memory, a magnetic disk, or an optical disk.

[0145] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present application, and that in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present application.

Claims

1. A method for predicting the magnetic field in a rescue well based on a three-layer resistance network model, characterized in that: include: Based on the current transmission characteristics of the downhole current injection method, the effective transmission surface is defined, and the current transmission is divided into three transmission layers: the emission layer, the convergence layer, and the receiving layer. The emission layer represents the current that converges from the emission electrode to the metal casing through different formation routes. The convergence layer represents the current on the metal casing flowing up and down along the pipe. The receiving layer represents the current that flows back to the ground electrode through different formation routes. The length is The metal casing is divided into equal lengths Segment, get cutoff points; Based on the current transmission paths of each transmission layer, a three-layer resistance network model is constructed. The three-layer resistance network model includes the formation equivalent resistance, the metal casing equivalent resistance, and the stray equivalent resistance. Solve the three-layer resistor network model based on Kirchhoff's law to determine the current at each intercept point and the loop voltage of the three-layer resistor network model; Based on the Bio-Savart law, combined with the current and loop voltage at each intercept point, the magnetic field generated by the metal casing at each position in the underground space of the rescue well is determined, and then the magnetic field distribution in the underground space of the rescue well is determined.

2. The method for predicting the downhole magnetic field of a rescue well based on a three-layer resistance network model according to claim 1, characterized in that: In the length The metal casing is divided into equal lengths Segment, get After the cutoff points, The cutoff point is recorded as , ; Based on the current transmission paths of each transmission layer, a three-layer resistor network model is constructed, including: Assume that the direction of the formation current in the three-layer resistance network model is from the transmitting electrode to the grounding electrode, and the output current of the transmitting electrode is , the emission layer The transmission current of the transmission path is , the first The transmission current of the transmission path is , the receiving layer The transmission current of the transmission path is , the total stray branch current is ; Set the emitter electrode to the metal sleeve Cutoff points The equivalent resistance is , the first Cutoff points To Cutoff points The equivalent resistance is , the first Cutoff points The equivalent resistance to the return electrode is , the branch resistance of the stray current flowing through the total equivalent branch is .

3. A method for predicting the downhole magnetic field of a rescue well based on a three-layer resistance network model according to claim 2, characterized in that: The first Cutoff points The equivalent resistance , and the first Cutoff points Equivalent resistance to return electrode , are equivalent formation resistances; It is expressed by the formula: ； ； in, is the resistivity of the formation, is the conductivity of the formation, and They are the emission layer The length and cross-sectional area of ​​the transmission path segment, is the radius of the metal casing; It is expressed by the formula: ； ； in, and The receiving layer The length and cross-sectional area of ​​the transmission path.

4. A method for predicting the downhole magnetic field of a rescue well based on a three-layer resistance network model according to claim 3, characterized in that: The metal casing Cutoff points To Cutoff points The equivalent resistance is the equivalent resistance of the metal casing; It is expressed by the formula: ； ； in, is the resistivity of the metal casing, is the conductivity of the metal casing, The first The length of the transmission path is related to the length of the metal sleeve. Segment length equal, The first The cross-sectional area of ​​the transmission path.

5. A method for predicting the downhole magnetic field of a rescue well based on a three-layer resistance network model according to claim 4, characterized in that: Solve the three-layer resistor network model based on Kirchhoff's law to determine the current at each intercept point, including: Based on Kirchhoff's law, the sum of all currents entering the intercept point in the three-layer resistor network model is determined to be 0; For the emitting electrode, its current satisfies the following relationship: ； For each intercept point on the metal casing, the current satisfies the following relationship: ； For the return electrode, since the return electrode is grounded, there is no need to consider the current at the intercept point.

6. A method for predicting the downhole magnetic field of a rescue well based on a three-layer resistance network model according to claim 5, characterized in that: Determine the loop voltage for a three-layer resistor network model, including: Based on Kirchhoff's law, the sum of all voltages in the circuit loop of the three-layer resistor network model is determined to be 0. The loop voltage of the three-layer resistor network model is divided into three parts: the transmitting and receiving loops of the converged current on each section of the metal casing, and the branch path of the stray current. For the emission loop of the converged current on each section of the metal casing, the voltage equation is: ； ； For the receiving loop of the converged current on each section of the metal casing, the voltage equation is: ； ； For stray current flowing through a branch, the voltage equation is: 。 7. A method for predicting the downhole magnetic field of a rescue well based on a three-layer resistance network model according to claim 6, characterized in that: Based on the Bio-Savart law, combined with the current and loop voltage at each intercept point, the magnetic field generated by the metal casing at each position in the underground space of the rescue well is determined, and then the magnetic field distribution in the underground space of the rescue well is determined, including: Based on the Bio-Savart law, determine the The metal casing is located at a point in the underground space. The magnetic field generated at is: ； in, For the The length of the metal casing, , is the vacuum permeability, For the Metal casing to The unit vector of the point, For the Metal casing to The distance vector of the point, For the Section metal casing The magnetic field generated by the point; The following formula is used to calculate the position of each section of metal casing at a point in the underground space: The vector sum of the magnetic field generated at the point is the sum of the magnetic field at the point where the entire metal casing is located in the downhole space. The magnetic field generated at: ； in, Indicates that the entire metal casing is The magnetic field generated by the point.

8. A rescue well downhole magnetic field prediction system based on a three-layer resistance network model, characterized in that: include: The transmission layer division module is used to define the effective transmission surface based on the current transmission characteristics of the downhole current injection method, and divide the current transmission into three transmission layers: the transmitting layer, the convergence layer, and the receiving layer. The transmitting layer represents the current converged from the transmitting electrode to the metal casing through different formation routes. The convergence layer represents the current on the metal casing flowing up and down along the pipe. The receiving layer represents the current flowing back to the grounding electrode through different formation routes. The truncation module is used to divide the length The metal casing is divided into equal lengths Segment, get cutoff points; A model building module is used to build a three-layer resistance network model based on the current transmission path of each transmission layer. The three-layer resistance network model includes the formation equivalent resistance, the metal casing equivalent resistance, and the stray equivalent resistance; A model solving module, used to solve the three-layer resistor network model based on Kirchhoff's law, determine the current at each intercept point, and determine the loop voltage of the three-layer resistor network model; The magnetic field calculation module is used to determine the magnetic field generated by the metal casing at various positions in the underground space of the rescue well based on the Bio-Savart law and combined with the current and loop voltage at each intercept point, and then determine the magnetic field distribution in the underground space of the rescue well.

9. An electronic device, characterized in that: include: at least one processor; and, a memory communicatively coupled to the at least one processor; In which, the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute a method for predicting underground magnetic fields in a rescue well based on a three-layer resistance network model as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it can implement a method for predicting the downhole magnetic field of a rescue well based on a three-layer resistance network model as described in any one of claims 1 to 7.

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