Determination method and enhancement method for magnetic field intensity of underground electromagnetic communication transmitting coil

Abstract

A method for determining the magnetic field intensity of an underground electromagnetic communication transmitting coil comprises the steps that related parameters of the underground electromagnetic communication transmitting coil are obtained, and the related parameters comprise the geometric parameters of the transmitting coil, the input voltage and current parameters and the magnetic core physical property parameters; acquiring a pre-established magnetic field distribution model; and determining the magnetic field intensity of the underground electromagnetic communication transmitting coil by using the magnetic field distribution model according to the related parameters.

Description

Technical Field

[0001] This article relates to the field of downhole wireless communication technology in the petroleum industry, and in particular to a method for determining and enhancing the magnetic field strength of a downhole electromagnetic communication transmitting coil. Background Technology

[0002] Downhole electromagnetic wave communication technology has a wide range of applications, high communication speed, and low cost, and can effectively realize real-time uploading of downhole data, showing great potential for development in the petroleum industry. Due to the limited space and complex medium downhole, the transmitting system antenna mainly modulates ultra-low frequency electromagnetic signals in the form of coils, using the casing and formation as channels to transmit to the surface. To improve the propagation distance and reduce the power consumption of the transmitting system, the design of the transmitting coil needs to be optimized. Currently, the design of downhole solenoid coils mainly focuses on structural development and positioning method design. For example, the patent "A retractable multi-coil downhole communication short section" (CN215332706U) proposes a retractable structure device to address the problem of fixed coil length and inconvenient positioning in conventional systems; the patent "A magnetic induction ground-penetrating positioning method for downhole transmitting coils in an inclined state" (CN116989773A) optimizes the downhole transmitting coil in an inclined state to achieve accurate positioning, addressing the problem of large positioning errors during mine accidents.

[0003] Currently, there is no method that can accurately calculate the magnetic field strength of an underground ultra-low frequency transmitting coil. Therefore, it is urgent to propose a method for calculating the magnetic field strength of an underground ultra-low frequency transmitting coil, which can accurately calculate the magnetic field strength and provide optimization suggestions based on the method to effectively improve the communication distance of underground electromagnetic waves. Summary of the Invention

[0004] This application provides a method for determining the magnetic field strength of a downhole electromagnetic communication transmitting coil. By establishing a magnetic field distribution model of a solenoid coil, the magnetic field strength of the downhole electromagnetic communication transmitting coil can be accurately obtained. This application also provides a method for enhancing the magnetic field strength of a downhole electromagnetic communication transmitting coil. By analyzing the magnetic field distribution model of the solenoid coil, influencing factors are identified, thereby improving the electromagnetic communication transmitting coil and enhancing the downhole electromagnetic wave communication distance.

[0005] In a first aspect, this application provides a method for determining the magnetic field strength of an underground electromagnetic communication transmitting coil, the method comprising:

[0006] Obtain relevant parameters of the downhole electromagnetic communication transmitting coil, including: geometric parameters of the transmitting coil, input voltage and current parameters, and magnetic core physical property parameters;

[0007] Obtain a pre-established magnetic field distribution model;

[0008] Based on the relevant parameters, the magnetic field strength of the downhole electromagnetic communication transmitting coil is calculated using the magnetic field distribution model.

[0009] Optionally, the process of establishing a magnetic field distribution model is as follows:

[0010] Obtain a magnetic field distribution model for a solenoid coil with a magnetic core;

[0011] The magnetic field distribution model of the solenoid coil with a magnetic core is simplified to obtain a simplified magnetic field distribution model.

[0012] A magnetic field distribution model is established based on the simplified magnetic field distribution model and related equivalent parameters.

[0013] Optionally, the magnetic field distribution model of the solenoid coil with a magnetic core is as follows:

[0014]

[0015] In the above formula, denoted as magnetic field strength, r as the position vector from the observation point to the magnetic dipole, I as the current in the coil, S as the equivalent area of ​​the coil, and k as the propagation constant, k = 2π / λ, where λ is the wavelength. Let r be the unit vector in the direction of r;

[0016] Let θ be the unit vector in the θ direction.

[0017] Optionally, the simplified magnetic field distribution model is as follows:

[0018]

[0019] In the above formula, Where is the magnetic field strength, N is the number of coils, r is the position vector from the observation point to the magnetic dipole, and I is the current in the coil; D e The equivalent diameter of the coil; Let r be the unit vector in the direction of r; Let θ be the unit vector in the θ direction.

[0020] Optionally, the equivalent parameter includes: equivalent diameter;

[0021] The equivalent diameter is:

[0022]

[0023] In the above formula, D1 is the outer diameter of the coil, D0 is the inner diameter of the coil, n is the number of coil layers, d is the diameter of the wire, and D... i This is the equivalent diameter.

[0024] Optionally, the magnetic field distribution model:

[0025]

[0026] In the above formula, U is the magnetic field strength. L Where N is the voltage across the coil terminals, and D is the number of coils. e The equivalent diameter of the coil, Let ω be the unit vector in the direction of r, ω be the phase angle in radians of the current change per unit time, L be the coil inductance, and r be the position vector from the observation point to the magnetic dipole. t K is the coil length. D Where is the solenoid end coefficient, K is the propagation constant, ΔU is the saturation voltage drop of the power amplifier tube, U is the power supply voltage provided by the power amplifier circuit, and L is the solenoid end coefficient. c is the length of the magnetic core.

[0027] Secondly, this application also provides a method for enhancing the magnetic field strength of an underground electromagnetic communication transmitting coil, the method comprising:

[0028] The method for determining the magnetic field strength of the downhole electromagnetic communication transmitting coil as described in any of the above embodiments is used to determine the parameters affecting the magnetic field strength.

[0029] Based on the influence parameters of the magnetic field strength, the improved electromagnetic communication transmitting coil structure is obtained.

[0030] Optionally, the parameters affecting the magnetic field strength include: core material, coil winding method, and input voltage.

[0031] Optionally, the improved electromagnetic communication transmitting coil is wound using a double-wire winding method.

[0032] Optionally, the magnetic core material is permalloy.

[0033] Compared with related technologies, this application provides a method for determining the magnetic field strength of a downhole electromagnetic communication transmitting coil. The method includes: acquiring relevant parameters of the downhole electromagnetic communication transmitting coil, including geometric parameters, input voltage and current parameters, and core property parameters; acquiring a pre-established magnetic field distribution model; and determining the magnetic field strength of the downhole electromagnetic communication transmitting coil using the magnetic field distribution model based on the relevant parameters. This application can accurately calculate the magnetic field strength of the downhole electromagnetic communication transmitting coil using its geometric dimensions, input voltage and current parameters, and core property parameters, and by utilizing the magnetic field distribution model.

[0034] This application proposes a method for enhancing the magnetic field strength of a downhole electromagnetic communication transmitting coil. The method includes: determining the influence parameters of the magnetic field strength using the method described in any of the above embodiments; and obtaining an improved electromagnetic communication transmitting coil structure based on the influence parameters of the magnetic field strength. This invention, by determining the influence parameters of the magnetic field strength and obtaining the improved electromagnetic communication transmitting coil structure, can effectively increase the downhole electromagnetic wave communication distance.

[0035] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the solutions described in the description and the accompanying drawings. Attached Figure Description

[0036] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0037] Figure 1 This is a flowchart illustrating the method for determining the magnetic field strength of an underground electromagnetic communication transmitting coil according to an embodiment of this application.

[0038] Figure 2 This is a flowchart illustrating a method for enhancing the magnetic field strength of a downhole electromagnetic communication transmitting coil according to an embodiment of this application.

[0039] Figure 3 This is a schematic diagram of a solenoid antenna in some exemplary embodiments;

[0040] Figure 4 This is a schematic diagram of a magnetic dipole in some exemplary embodiments;

[0041] Figure 5 This is a schematic diagram of the spherical coordinate system of the magnetic field of a solenoid coil in some exemplary embodiments;

[0042] Figure 6 This is a schematic diagram of solenoid dimensions in some exemplary embodiments. Detailed Implementation

[0043] This application describes several embodiments, but these descriptions are exemplary and not restrictive, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with, or may replace, any feature or element of any other embodiment.

[0044] This application includes and contemplates combinations of features and elements known to those skilled in the art. The embodiments, features, and elements disclosed in this application may also be combined with any conventional features or elements to form a unique inventive scheme as defined by the claims. Any feature or element of any embodiment may also be combined with features or elements from other inventive schemes to form another unique inventive scheme as defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in this application may be implemented individually or in any suitable combination. Therefore, the embodiments are not limited except by the limitations imposed by the appended claims and their equivalents. Furthermore, various modifications and changes may be made within the scope of the appended claims.

[0045] Furthermore, in describing representative embodiments, the specification may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described herein, to the extent that it does not depend on such a specific order. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation of the claims. Moreover, the claims concerning the method and / or process should not be limited to the steps performed in the written order, and those skilled in the art will readily understand that these orders can be varied and still remain within the spirit and scope of the embodiments of this application.

[0046] This invention provides a method for determining the magnetic field strength of a downhole electromagnetic communication transmitting coil, such as... Figure 1 As shown, the method includes steps S100-S120:

[0047] S 100: Obtain relevant parameters of the downhole electromagnetic communication transmitting coil;

[0048] S110: Obtain a pre-established magnetic field distribution model;

[0049] S 120: Based on the relevant parameters, the magnetic field strength of the downhole electromagnetic communication transmitting coil is calculated using the magnetic field distribution model.

[0050] In one exemplary embodiment, the relevant parameters include: geometric parameters of the transmitting coil, input voltage and current parameters, and magnetic core physical properties.

[0051] In one exemplary embodiment, the process of establishing the magnetic field distribution model is as follows:

[0052] The first step is to obtain a magnetic field distribution model of a solenoid coil with a magnetic core;

[0053] Considering the limited space and tubing structure downhole, the ultra-low frequency transmitting system employs a special "antenna," namely a solenoid coil with a magnetic core, structured as follows: Figure 3 The schematic diagram of the solenoid antenna is shown.

[0054] For Figure 3 The underground wireless communication antenna in the well can be equivalent to a coil with no length in the axial direction, i.e., a magnetic dipole. The magnetic field generated by the magnetic dipole can be described by the following formula:

[0055]

[0056]

[0057] H φ =0

[0058] In the above formula, Hr is the vector magnetic potential, H θ Let be the scalar magnetic potential, j be the current density vector, r be the position vector from the observation point to the magnetic dipole, and ω be the phase angle in radians of the current change per unit time; S be the area of ​​the equivalent current loop, I be the current in the current loop, and k be the propagation constant; r, θ, These are the three parameters of the spherical coordinate system.

[0059] The second step is to simplify the magnetic field distribution model of the solenoid coil with a magnetic core into a magnetic dipole, thus obtaining the simplified magnetic field distribution model.

[0060] In this step, a multi-layered solenoid with a magnetic core, a certain axial length, and a certain radial thickness can be simplified into a planar coil, i.e., a magnetic dipole, with no length and no thickness. Figure 4 The simplified schematic diagram of the magnetic dipole shown can be used to establish a magnetic field distribution model for the magnetic dipole:

[0061]

[0062] Since the vector distance from the observation point to the magnetic dipole is very small, i.e., r*k << 1, based on Figure 5The solenoid coil magnetic field is shown in spherical coordinates. The above model can be simplified to:

[0063]

[0064] Where: I is the current in the coil; De is the equivalent diameter of the coil; S is the equivalent area of ​​the coil; k is the propagation constant, k=2π / λ, λ is the wavelength; Let r be the unit vector in the direction of r; Let θ be the unit vector in the θ direction.

[0065] As can be seen from the simplified model above, the magnetic field strength of a magnetic dipole is mainly determined by the coil parameters N and the equivalent diameter D of the coil. e It is determined by the current I in the coil.

[0066] The third step is to establish the final magnetic field distribution model of the solenoid coil based on the simplified magnetic field distribution model and related equivalent parameters.

[0067] In this step, based on the transmitter's transmission circuit structure, we can conclude that:

[0068]

[0069] In the above formula, I is the current in the coil, and U L Let U be the voltage across the coil terminals, ω be the power supply voltage provided by the power amplifier circuit, ΔU be the saturation voltage drop of the power amplifier transistor, and L be the coil inductance. When U and ω are constant, the magnitude of the current depends on the coil inductance L. The coil inductance L is determined by the magnetic material, the number of coil turns, the coil geometry, and the magnetic circuit shape.

[0070] Inductors, used for electromagnetic energy conversion, are frequently used in circuits, especially in electronic circuits of different frequencies. To reduce the size of inductors and increase their inductance, magnetic cores are often incorporated. However, the nonlinearity of the permeability of magnetic materials makes calculating the inductance of solenoids with magnetic cores difficult, and to date, there is no reliable, accurate, and universally applicable formula for this purpose.

[0071] A magnetic field distribution model is established, and the relevant parameters are equivalent. The purpose of this equivalence is to make the formula calculation simpler and more practical. It is assumed that 1″ magnetic permeability is sufficiently large, which is usually sufficient. The specific equivalence is as follows:

[0072] (1) The relative permeability of the solenoid core is sufficiently large (generally around 10). 4 (Above), the magnetic core reluctance loss is zero:

[0073] (2) The equivalent diameter of a hollow multilayer solenoid can be obtained according to the equivalent magnetic moment:

[0074]

[0075] Where D1 is the outer diameter of the coil, D0 is the inner diameter of the coil, n+1 is the number of coil layers, and d is the diameter of the wire: D i This represents the equivalent diameter of the multilayer solenoid, calculated based on the equivalent magnetic moment.

[0076] (3) The same cross-section of the magnetic core of a solenoid is a magnetically equivalent surface. After a hollow solenoid is inserted into a magnetic core, its diameter increases by the diameter of one magnetic core.

[0077] In one exemplary embodiment, based on the above assumptions, combined with Figure 6 Given the dimensions of the solenoid, calculate the equivalent diameter and magnetic flux of the magnetic moment:

[0078]

[0079]

[0080] In the above formula, μ is the permeability; N is the number of turns of the coil; I is the current; L c L is the length of the magnetic core. t K is the coil length. D denoted as the solenoid end coefficient; μ0 is the permeability; De is the equivalent diameter; and ψ is the magnetic flux.

[0081] The inductance L can be obtained from the above formula:

[0082]

[0083] In the above formula, K is the propagation constant.

[0084] In one exemplary embodiment, the solenoid core causes an increase in inductance. Let α be the ratio of the inductance with and without the solenoid core. Then, α is the factor by which the solenoid inductance increases when the core is present.

[0085]

[0086] Based on the calculated α above, according to the following formula:

[0087]

[0088] Therefore, we can also obtain L = αL0.

[0089] The inductance L and the equivalent diameter D for calculating the magnetic moment are given. e Substitute into the following formula:

[0090]

[0091] Finally, by establishing the mathematical relationship between H and the geometric dimensions, material properties, and power supply voltage of the solenoid coil, the final magnetic field distribution model of the solenoid coil is obtained:

[0092]

[0093] In the above formula, U is the magnetic field strength. L Where N is the voltage across the coil terminals, and D is the number of coils. e The equivalent diameter of the coil, Let ω be the unit vector in the direction of r, ω be the phase angle in radians of the current change per unit time, L be the coil inductance, and r be the position vector from the observation point to the magnetic dipole. t Where L is the coil length, KD is the solenoid end coefficient, K is the propagation constant, ΔU is the saturation voltage drop of the power amplifier tube, U is the power supply voltage provided by the power amplifier circuit, and L is the solenoid end coefficient. c is the length of the magnetic core.

[0094] The method for determining the magnetic field strength of the downhole electromagnetic communication transmitting coil implemented in this embodiment has the following technical effects:

[0095] 1. A method for calculating the magnetic field strength of downhole ultra-low frequency solenoid communication coils was established, effectively filling a gap and providing a theoretical basis for optimization.

[0096] 2. Using the established magnetic field distribution model of the solenoid coil, the magnetic field strength can be calculated simply and accurately.

[0097] This application also discloses a method for enhancing the magnetic field strength of an underground electromagnetic communication transmitting coil, the method comprising:

[0098] Step 200: Determine the parameters affecting the magnetic field strength according to the method for determining the magnetic field strength of the downhole electromagnetic communication transmitting coil;

[0099] Step 210: Based on the influence parameters of the magnetic field strength, the improved electromagnetic communication transmitting coil structure is obtained.

[0100] In one exemplary embodiment, considering the limited downhole space and tubing structure, the ultra-low frequency transmitting system employs a special "antenna," namely a solenoid coil with a magnetic core, structured as follows: Figure 3 As shown; according to the above method for determining the magnetic field strength of the downhole electromagnetic communication transmitting coil, the magnetic field distribution model of the solenoid coil is determined; according to the above magnetic field distribution model of the solenoid coil, the geometric dimensions, material properties, and power supply voltage of the coil are known, while the magnetic field strength is unknown.

[0101] In one exemplary embodiment, the parameters affecting the magnetic field strength include: core material, coil winding method, and input voltage.

[0102] In one exemplary embodiment, the magnetic core is made of a high-permeability material, such as permalloy, or other high-permeability materials may be used.

[0103] In one exemplary embodiment, modifications can be made to each parameter affecting the magnetic field strength, such as changing the coil winding method, increasing the coil diameter, reducing the number of coil layers, and using double-wire winding. For example, to increase the coil diameter and reduce the number of coil layers, single-wire winding can be improved to double-wire winding, which can increase the magnetic field strength of the transmitting coil by approximately two times.

[0104] In one exemplary embodiment, the magnetic field strength of the transmitting system coil can also be proportionally increased by increasing the power supply input voltage.

[0105] In this embodiment, changing the structure of the coil achieves the following technical effects:

[0106] By selecting appropriate magnetic core materials and improving coil structure and circuit power design, magnetic field strength can be effectively increased, downhole communication distance can be extended, and the reliability of ground-based signal reception can be improved.

[0107] Example 1

[0108] This example demonstrates a method for calculating and optimizing the magnetic field strength of a downhole electromagnetic communication transmitting coil. The specific implementation process includes:

[0109] The first step is to analyze the existing downhole electromagnetic communication transmitting coils.

[0110] Considering the limited space and tubing structure downhole, the ultra-low frequency transmitting system employs a special "antenna," namely a solenoid coil with a magnetic core, structured as follows: Figure 3 As shown;

[0111] The second step is to simplify the underground wireless communication antenna into an equivalent planar coil, i.e., a magnetic dipole, that has no length and no thickness.

[0112] In this step, the downhole wireless communication antenna can be considered equivalent to a coil with no length in the axial direction, i.e., a magnetic dipole. The magnetic field generated by the magnetic dipole can be described using the following formula:

[0113]

[0114]

[0115] H φ =0

[0116] Where: S is the area of ​​the equivalent current loop, I is the current in the current loop, and k is the propagation constant. r, θ, These are the three parameters of the spherical coordinate system.

[0117] A multi-layered solenoid with a magnetic core, a certain length along its axis, and a certain thickness in its radial direction can usually be simplified into a planar coil, i.e., a magnetic dipole, that has no length and no thickness. Figure 4 As shown.

[0118] Step 3: Establish a magnetic field distribution model for a magnetic dipole.

[0119]

[0120] Since r*k << 1, the above model can be simplified to:

[0121]

[0122] Where I is the current in the coil; D e λ is the equivalent diameter of the coil; S is the equivalent area of ​​the coil; k is the propagation constant, k = 2π / λ, and λ is the wavelength; Let r be the unit vector in the direction of r; Let θ be the unit vector in the θ direction. As the model shows, the magnetic field strength of the magnetic dipole is mainly determined by the coil parameters N and D. e It is determined by the current I.

[0123] Step 4: Based on the equivalent parameters related to the transmitter's transmitting circuit structure.

[0124] In the fourth step, the transmitter circuit structure of the transmitter is first analyzed:

[0125]

[0126] U L U is the voltage across the coil terminals; U is the power supply voltage provided by the power amplifier circuit; ΔU is the saturation voltage drop of the power amplifier transistor; and L is the coil inductance. When U and ω are constant, the current depends on the coil inductance L. L is determined by the magnetic material, the number of coil turns, the coil geometry, and the magnetic circuit shape.

[0127] Secondly, based on the circuit structure, the following assumptions are made:

[0128] (1) The relative permeability of the solenoid core is sufficiently large (generally around 10). 4 (Above), the magnetic core reluctance loss is zero.

[0129] (2) The equivalent diameter of a hollow multilayer solenoid can be obtained according to the equivalent magnetic moment:

[0130]

[0131] Where D1 is the outer diameter of the coil, D0 is the inner diameter of the coil, n+1 is the number of coil layers, and d is the diameter of the wire.

[0132] (3) The same cross-section of the magnetic core of a solenoid is a magnetically equivalent surface. After a hollow solenoid is inserted into a magnetic core, its diameter increases by the diameter of one magnetic core.

[0133] Based on the above assumptions, calculate the equivalent diameter of the magnetic moment and the magnetic flux:

[0134]

[0135]

[0136] Where KD is the solenoid end coefficient, and the inductance L can be obtained from the above formula:

[0137]

[0138] As shown above, the magnetic core of a solenoid increases its inductance. Let 'a' be the ratio of the inductance with and without a magnetic core. Then, 'a' is the factor by which the inductance of the solenoid increases when a magnetic core is present.

[0139]

[0140] Step 5: Establish a magnetic field distribution model

[0141] Finally, a mathematical relationship is established between H and the coil's geometric dimensions, material properties, and power supply voltage, i.e., a magnetic field distribution model:

[0142]

[0143] In the above formula, U is the magnetic field strength. L Where N is the voltage across the coil terminals, and D is the number of coils. e The equivalent diameter of the coil, Let ω be the unit vector in the direction of r, ω be the phase angle in radians of the current change per unit time, L be the coil inductance, and r be the position vector from the observation point to the magnetic dipole. t K is the coil length. D Where is the solenoid end coefficient, K is the propagation constant, ΔU is the saturation voltage drop of the power amplifier tube, U is the power supply voltage provided by the power amplifier circuit, and L is the solenoid end coefficient. c is the length of the magnetic core.

[0144] Step 6: Determine the parameters affecting the magnetic field strength based on the final magnetic field distribution model of the solenoid coil;

[0145] The parameters affecting the magnetic field strength include: core material, coil winding method, and input voltage.

[0146] Step 7: Based on the determined parameters affecting the magnetic field strength, formulate modification methods for each parameter to obtain the modified structure of the electromagnetic communication transmitting coil.

[0147] Based on the above model, it can be seen that increasing the magnetic field strength of the downhole transmitting coil can be achieved in the following ways:

[0148] (1) The magnetic core is made of a high-permeability material, such as permalloy.

[0149] (2) Increasing the coil diameter and reducing the number of coil layers, and improving the single-wire winding to double-wire winding, can increase the magnetic field strength of the transmitting coil by about two times.

[0150] (3) Increasing the power supply input voltage can proportionally enhance the magnetic field strength of the transmitting system coil.

[0151] The method for calculating and optimizing the magnetic field strength of the downhole electromagnetic communication transmitting coil implemented in this example has the following technical advantages:

[0152] 1. A method for calculating the magnetic field strength of downhole ultra-low frequency solenoid communication coils was established, effectively filling a gap in the field and providing a theoretical basis for optimization;

[0153] 2. By scientifically selecting magnetic cores, optimizing coil structure, and designing circuit power, the magnetic field strength can be effectively improved, the underground communication distance can be increased, and the reliability of ground signal reception can be enhanced.

[0154] It will be understood by those skilled in the art that all or some of the steps, systems, or apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software may be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

Claims

1. A method for determining the magnetic field strength of an underground electromagnetic communication transmitting coil, characterized in that, The method comprises: acquiring relevant parameters of the downhole electromagnetic communication transmitting coil, the relevant parameters comprising: geometric parameters of the transmitting coil, input voltage and current parameters, and magnetic core physical property parameters; acquiring a pre-established magnetic field distribution model; determining the magnetic field strength of the downhole electromagnetic communication transmitting coil according to the relevant parameters and the magnetic field distribution model.

2. The method of claim 1, wherein the magnetic field strength of the downhole electromagnetic communication transmitter coil is determined by: The process of establishing the magnetic field distribution model is: acquiring a magnetic field distribution model of a solenoid coil with a magnetic core; simplifying the magnetic field distribution model of the solenoid coil with a magnetic core to obtain a simplified magnetic field distribution model; establishing the magnetic field distribution model according to the simplified magnetic field distribution model and relevant equivalent parameters.

3. The method of claim 1, wherein the magnetic field strength of the downhole electromagnetic communication transmitter coil is determined by: The magnetic field distribution model of the solenoid coil with a magnetic core is: In the above equation, is the magnetic field strength, I is the current in the coil, S is the equivalent area of the coil; k is the propagation constant, k = 2π / λ, λ is the wavelength; r is the position vector of the observation point to the magnetic dipole, is the unit vector in the r direction; is a unit vector in the direction of θ.

4. The method of claim 3, wherein the magnetic field strength of the downhole electromagnetic communication transmitter coil is determined by: The simplified magnetic field distribution model is: In the above equation, is the magnetic field strength, N is the number of coils, r is the position vector of the observation point to the magnetic dipole, I is the current in the coil; D e is the equivalent diameter of the coil; is the unit vector in the r direction; is the unit vector in the θ direction.

5. The method of claim 2, wherein the magnetic field strength of the downhole electromagnetic communication transmitter coil is determined by: The equivalent parameters comprise: an equivalent diameter; The equivalent diameter is: In the above equation, D i is the equivalent diameter, D1 is the outer diameter of the coil, D0 is the inner diameter of the coil, n is the number of layers of the coil, and d is the diameter of the wire.

6. The method for determining the magnetic field strength of the downhole electromagnetic communication transmitting coil according to claim 1, characterized in that, The magnetic field distribution model is: In the above formula, is the magnetic field strength, U L is the coil end voltage, N is the number of coils, D e is the equivalent diameter of the coil, is the unit vector in the r direction, ω is the phase angle radian of current change per unit time, L is the coil inductance, r is the position vector from the observation point to the magnetic dipole, L t is the coil length, K D is the solenoid end coefficient, K is the propagation constant, ΔU is the saturation voltage drop of the power amplifier tube, U is the power supply voltage provided by the power amplifier circuit, L c is the core length.

7. A method of enhancing the magnetic field strength of a downhole electromagnetic communication transmitter coil, the method comprising: The method comprises: determining the magnetic field strength influencing parameters according to the method for determining the magnetic field strength of the downhole electromagnetic communication transmitting coil according to any one of the above methods 1-6; obtaining an improved electromagnetic communication transmitting coil according to the magnetic field strength influencing parameters.

8. The method for enhancing the magnetic field strength of the downhole electromagnetic communication transmitting coil according to claim 7, characterized in that, The magnetic field strength influencing parameters comprise: magnetic core material, coil winding method, and input voltage.

9. The method of claim 8, wherein the method further comprises, The coil winding method of the improved electromagnetic communication transmitting coil is double-wire winding.

10. The method of claim 8, wherein the method further comprises, The magnetic core material is permalloy material.

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