A method for analyzing the generation of downhole continuous wave mud pulse signals

Abstract

The present invention discloses a method for analyzing the generation of downhole continuous wave mud pulse signals, which belongs to the field of downhole data transmission of oil and natural gas, and includes the following steps: S1, using transient theory to establish a one-dimensional mathematical model for the generation of downhole continuous wave mud pulses; S2, using characteristic line method to numerically discretize the nonlinear equation group in the one-dimensional mathematical model; S3, mathematically characterizing the initial conditions of drilling and the boundary conditions of the pulser; S4, performing sensitivity analysis of the continuous wave generation signal under different drilling parameters and hydraulic parameters. The present invention adopts the above-mentioned method for analyzing the generation of downhole continuous wave mud pulse signals, which provides a powerful technical means for quickly analyzing the generation quality and influencing factors of downhole continuous wave signals, can effectively improve the quality of continuous wave signals, and ensure the high-speed transmission of logging data.

Description

Technical Field

[0001] The invention relates to the field of downhole data transmission for oil and natural gas, and in particular to a method for generating and analyzing downhole continuous wave mud pulse signals. Background Art

[0002] During the oil drilling process, logging while drilling (MWD) technology can obtain the geophysical properties of underground rocks and fluids in real time, effectively unlock the complex underground oil and gas resources, and significantly increase the economic reserves of oil and gas. It is a key core technology for oil and gas exploration and development. At present, continuous wave mud pulse is a common underground wireless data transmission method at home and abroad. It is the most widely used in drilling sites due to its high comprehensive cost-effectiveness and reliable operation. However, with the continuous increase in downhole instruments and the complexity of drilling information, the objective contradiction between the large amount of downhole data and the low transmission rate that lies in the development of MWD has become increasingly prominent, seriously affecting the real-time comprehensive evaluation efficiency of drilling projects.

[0003] The domestic research started late, and domestic scholars only started to develop continuous wave pulsers in the 1990s. Although a series of studies have been conducted on the generation mechanism of high-speed continuous wave pulses in the well and certain results have been achieved, there are still some shortcomings: continuous wave mud pulses are generally used in the measurement while drilling or rotary steering process of deep wells. The ground experimental pipelines are complex, expensive and time-consuming, and there are certain differences from the actual operating conditions in the well. The experimental results are difficult to be directly applied to the actual drilling conditions. When simulating the flow characteristics of the continuous wave full wellbore, the CFD numerical simulation model has a large grid volume and low calculation efficiency. Therefore, it is urgent to establish a simple and efficient technical method that can be used to study the generation of continuous waves in the well. Summary of the invention

[0004] The purpose of the present invention is to provide a method for generating and analyzing downhole continuous wave mud pulse signals, which provides a powerful technical means for quickly analyzing the generation quality and influencing factors of downhole continuous wave signals, can effectively improve the quality of continuous wave signals, and ensure high-speed transmission of logging data.

[0005] To achieve the above object, the present invention provides a method for analyzing downhole continuous wave mud pulse signal generation, comprising the following steps:

[0006] S1. Use transient theory to establish a one-dimensional mathematical model of downhole continuous wave mud pulse generation;

[0007] S2, numerical discretization of nonlinear equations in one-dimensional mathematical models using characteristic line method;

[0008] S3, mathematically characterize the initial drilling conditions and pulser boundary conditions;

[0009] S4. Conduct sensitivity analysis of continuous wave generation signals under different drilling parameters and hydraulic parameters.

[0010] Preferably, step S1 specifically comprises:

[0011] S101. Select the wellbore microelement dx through which the drilling fluid flows in the time dt as the control body for analysis, where the flow direction is the positive direction of x, and the angle between the wellbore and the horizontal is θ. According to Euler's transport theorem and the mass conservation theorem, it is calculated that:

[0012]

[0013] Among them, m1 and m2 are the masses flowing in and out of the micro-element control body, A is the cross-sectional area in the wellbore, v is the flow velocity of the fluid in the wellbore, ρ is the fluid density, and t is the time;

[0014] S102. For fluid, the volume elastic coefficient K is:

[0015]

[0016] Where P is the fluid pressure. For a uniform circular tube, the relationship between the cross-sectional change rate and the elastic modulus E, the tube wall diameter D and the strain δ is:

[0017]

[0018] The ideal wave velocity a of the fluid in the circular tube is:

[0019]

[0020] Simplifying the continuity equation, we get:

[0021]

[0022] S103, taking the wellbore microelement dx as the research object, performing force analysis on it, and deriving the motion equation as follows:

[0023]

[0024] Where g is the acceleration due to gravity, and the wall shear force in steady flow is Substituting into equation (6) and expanding it, we get the following motion equation:

[0025]

[0026] Where, f is the friction coefficient;

[0027] S104. In summary, the one-dimensional mathematical equations for the generation and transmission of continuous waves in the wellbore are obtained:

[0028]

[0029] The pressure P is expressed by the pressure head H. Since P = pg (HH-z), and is a second-order small quantity, so formula (8) is simplified to:

[0030]

[0031] Preferably, step S2 specifically comprises:

[0032] S201. Express equation (9) with L1 and L2 respectively, introduce the real number λ, multiply by L2 and add L1, the sum is still equal to zero:

[0033]

[0034] S202. According to the total differential form of the composite function of H and v, let

[0035]

[0036] The total differential equation of formula (9) is calculated as:

[0037]

[0038] According to equations (11) and (12), we can obtain the positive and negative compatible total differential equation, where along the positive characteristic line:

[0039]

[0040] Along the negative characteristic line direction:

[0041]

[0042] S203. For the positive and negative compatible equations, a conventional difference grid is constructed. There are three points A, B, and P in the difference grid. The diagonal AP is called the positive characteristic line, and the diagonal BP is called the negative characteristic line. Integrate equations (13) and (14) along the positive characteristic line and the negative characteristic line in the difference grid, respectively, to obtain:

[0043]

[0044] Among them, point P represents the unknown parameter at the i-th pipe section at time j, and points A and B represent the known parameters at the i-1 and i+1 pipe sections at time j-1 respectively; H P , H A , H B Represent the pressure head at point P, point A, and point B respectively; v P 、v A 、v B Represent the speeds of point P, point A, and point B respectively; t P ,tA ,t B Respectively represent the time of point P, point A, and point B;

[0045] S204, Order The velocity and pressure head at point P at time j are obtained as follows:

[0046]

[0047] Among them, C P is variable 1; D P is variable 2; C M is variable three; D M is variable four.

[0048] Preferably, in step S3, the equation group discretized in step S2 is solved in combination with the downhole initial conditions and the boundary conditions of the drilling pump, the pulser and the outlet blowout preventer, specifically:

[0049] S301, when the continuous wave pulser is not working, the rotor is in a fully open state. At this time, the flow in the pipeline is in a stable flow. The initial condition is set, the outlet is at atmospheric pressure, and the minimum local pressure drop when the rotor is opened is The water head and flow velocity of each microelement segment at the initial moment are expressed as:

[0050]

[0051] Among them, Q0 is the flow rate in the wellbore at the initial moment;

[0052] S302. Solve the drilling pump boundary conditions. The drilling pump boundary flow and pressure head are expressed as:

[0053]

[0054] Among them, Q in is the inlet flow rate; A in is the cross-sectional area of ​​the inlet pipe;

[0055] S303, the left and right sides of the pulser satisfy the conservation of mass and energy, where the conservation of mass means that the node flow rates on the left and right sides are equal:

[0056]

[0057] Among them, the subscripts ML and MR represent the pulser left node and the pulser right node respectively, and M represents the pulser node; Indicates the speed of the node on the left side of the pulser; represents the node velocity on the right side of the pulser; v M Indicates the pulser node speed; A j is the flow area at the pulser;

[0058] The energy on the left and right sides of the pulser is conserved, and its pressure loss is expressed as:

[0059]

[0060] in, Indicates the pressure head on the left side of the pulser; Indicates the pressure head on the right side of the pulser; C d It indicates the throttling coefficient; Indicates the pulser flow rate;

[0061] The left and right sides of the pulser satisfy the positive and negative compatibility equations respectively:

[0062]

[0063] The flow velocity at the pulse node is obtained by combining equations (19)-(21):

[0064]

[0065] make The combined equations (19)-(22) are used to calculate the pressure head and flow rate at the left and right nodes of the pulser.

[0066] Preferably, in step S4, the one-dimensional mathematical model and numerical solution method established in steps S1-S3 are used to set different drilling parameters and hydraulic parameters, and the influence of the continuous wave amplitude and waveform on the parameters is analyzed to obtain the corresponding continuous wave signal.

[0067] Therefore, the present invention adopts the above-mentioned downhole continuous wave mud pulse signal generation analysis method to accurately describe the downhole continuous wave mud pulse generation process. By considering the mass and movement state of the micro-element in the wellbore when the pulser is working, a one-dimensional mathematical model of downhole continuous wave generation is established, and the characteristic line method is used for numerical discretization. The initial distribution conditions of the wellbore pressure and flow are comprehensively considered, and the boundary conditions of the drilling pump, continuous wave pulser and wellhead blowout preventer are coupled. The discrete equations of each boundary point are established and iteratively solved, thereby completing the numerical solution of the continuous wave generation of the entire wellbore node.

[0068] In summary, a concise and efficient analysis method for downhole continuous wave mud pulse generation is formed, which provides a powerful technical means for quickly and effectively analyzing the generation quality and influencing factors of downhole continuous wave signals, can effectively improve the quality of continuous wave signals and ensure high-speed transmission of logging data.

[0069] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1It is a flow chart of an embodiment of a method for analyzing downhole continuous wave mud pulse signal generation according to the present invention;

[0071] Figure 2 It is a model diagram of a micro-element control body in a wellbore according to an embodiment of a method for analyzing a downhole continuous wave mud pulse signal generation;

[0072] Figure 3 It is a micro-element force diagram of a wellbore according to an embodiment of a method for analyzing a downhole continuous wave mud pulse signal generation;

[0073] Figure 4 It is a characteristic line method node grid of an embodiment of a method for analyzing downhole continuous wave mud pulse signal generation;

[0074] Figure 5 It is a schematic diagram of the drilling pump inlet boundary of an embodiment of a method for analyzing downhole continuous wave mud pulse signal generation according to the present invention;

[0075] Figure 6 It is a simplified schematic diagram of the boundary conditions of a continuous wave mud pulser in an embodiment of a method for analyzing the generation of a downhole continuous wave mud pulse signal according to the present invention;

[0076] Figure 7 It is a schematic diagram of the atmospheric pressure outlet boundary of an embodiment of a method for analyzing downhole continuous wave mud pulse signal generation according to the present invention;

[0077] Figure 8 It is a continuous wave signal at different flow rates in an embodiment of a method for generating and analyzing a downhole continuous wave mud pulse signal of the present invention. DETAILED DESCRIPTION

[0078] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0079] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0080] Embodiment 1

[0081] The present invention provides an analysis method for the generation of downhole continuous wave mud pulse signals. The method establishes a one-dimensional mathematical model for the generation of downhole continuous wave signals based on transient flow theory, uses a characteristic line method for numerical discretization, and couples initial conditions under drilling conditions and boundary conditions such as continuous wave pulses to solve the problem. Figure 1 This is a flow chart of the analysis method provided by the present invention, including steps S1 to S4.

[0082] Among them, step S1, using transient flow theory to establish a one-dimensional mathematical model of continuous wave mud pulse generation in the wellbore, the specific method is as follows:

[0083] S101. The generation and transmission of continuous waves in the wellbore is essentially the transmission of pressure in the pipeline after hydraulic transient, which can be described by the continuity equation and the motion equation. Figure 2 As shown in the figure, the wellbore microelement dx through which the drilling fluid flows in the time dt is selected as the control body for analysis, where the flow direction is the positive direction of x, and the angle between the wellbore and the horizontal is θ. According to the Euler transport theorem and the mass conservation theorem, it is calculated that:

[0084]

[0085] Among them, m1 and m2 are the masses flowing in and out of the micro-element control body, A is the cross-sectional area in the wellbore, v is the flow velocity of the fluid in the wellbore, ρ is the fluid density, and t is the time;

[0086] S102. For fluid, the volume elastic coefficient K is:

[0087]

[0088] Where P is the fluid pressure. Similarly, for a uniform circular tube, the relationship between the cross-sectional change rate and the elastic modulus E, the tube wall diameter D and the strain δ is:

[0089]

[0090] The formula for the ideal wave velocity a of the fluid in a circular tube is:

[0091]

[0092] Simplifying the continuity equation, we get:

[0093]

[0094] S103, taking the wellbore microelement dx as the research object, such as Figure 3 As shown, the force analysis is performed on it, and according to Newton's second law ∑F=ma, ignoring the second-order infinitesimal, the motion equation is derived as follows:

[0095]

[0096] Where g is the acceleration due to gravity; according to the Darcy-Weisbach formula, the wall shear force in steady flow is Substituting into equation (6) and expanding it, we get the following motion equation:

[0097]

[0098] Where, f is the friction coefficient;

[0099] S104. In summary, the one-dimensional mathematical equations for the generation and transmission of continuous waves in the wellbore are obtained:

[0100]

[0101] The pressure P is expressed by the pressure head H. Since P = ρg (Hz), and is a second-order small quantity, so formula (8) is simplified to:

[0102]

[0103] Step S2, using the characteristic line method to perform numerical discretization of the nonlinear equation group in the one-dimensional mathematical model, the specific method is as follows:

[0104] The one-dimensional equation of motion and continuity equation of the wellbore in step S1 are hyperbolic partial differential equations, which involve a variety of complex boundary conditions and are difficult to obtain accurate analytical solutions, so a numerical solution is required. In traditional pipeline transient flow research, commonly used solution methods include: characteristic line, graphical method, finite element method, etc. Among them, the characteristic line method can transform the partial differential equation into an ordinary differential equation along the characteristic line, and has high accuracy and simple programming. It can accurately simulate the peak and transmission attenuation process of the continuous wave. Therefore, the present invention adopts the characteristic line method to discretely solve the equation.

[0105] S201. Express equation (9) with L1 and L2 respectively, introduce the real number λ, multiply by L2 and add L1, the sum is still equal to zero:

[0106]

[0107] S202. According to the total differential form of the composite function of H and v, let

[0108]

[0109] The total differential equation of formula (9) is calculated as:

[0110]

[0111] According to equations (11) and (12), we can obtain the positive and negative compatible total differential equation, where along the positive characteristic line:

[0112]

[0113] Along the negative characteristic line direction:

[0114]

[0115] S203. For the positive and negative compatible equations, a conventional differential grid is constructed. First, the wellbore of length L is divided into N segments, each segment is Δx = L / N, called the space step, and has a total of N+1 nodes; the vertical axis is the time axis, and the length of each unit is Δt = Δx / a, called the time step. In the differential grid constructed under this rule, if Figure 4 As shown, the diagonal line AP is called the positive characteristic line, which satisfies Δx = aΔt and has a slope of 1 / a; while the diagonal line BP is called the negative characteristic line, which satisfies Δx = -aΔt and has a slope of -1 / a. Among them, point P represents the unknown parameter at the i-th pipe section at time j, and points A and B are the known parameters at the i-1 and i+1 pipe sections at time j-1, respectively. Integrate equations (13) and (14) along the positive characteristic line and negative characteristic line in the differential grid, respectively, to obtain:

[0116]

[0117] Among them, point P represents the unknown parameter at the i-th pipe section at time j, and points A and B represent the known parameters at the i-1 and i+1 pipe sections at time j-1 respectively; H P , H A , H B Represent the pressure head at point P, point A, and point B respectively; v P 、v A 、v B Represent the speeds of point P, point A, and point B respectively; t P ,t A ,t B Respectively represent the time of point P, point A, and point B;

[0118] S204. The last term in equation (15) represents the friction term generated in the flow, which is a nonlinear term. The present invention adopts a first-order implicit approximation process, and lets At the same time, point A, point B and point P are represented by corresponding subscripts. Point P is at the i-th pipe section at time j, and point A and point B are the i-1 and i+1 pipe sections at time j-1, respectively. The calculation results are:

[0119]

[0120] make The velocity and pressure head at point P at time j are obtained as follows:

[0121]

[0122] Among them, C P is variable 1; D P is variable 2; C M is variable three; D M is variable four.

[0123] At this point, step S2 completes the establishment of a one-dimensional mathematical model. When solving the problem, a stable initial state is first given, that is, the H and v values ​​at time t = 0 are known. When t = Δt, the H and v values ​​of each node are calculated by formula (17), and the physical values ​​at all times are obtained in this way.

[0124] Step S3, mathematically characterize the initial drilling conditions and the pulser boundary conditions, and solve the equations according to the discretized equations in step S2, combined with the downhole initial conditions and the boundary conditions of the drilling pump, the pulser, and the outlet blowout preventer, specifically:

[0125] S301, when the continuous wave pulser is not working, the rotor is in a fully open state. At this time, the flow in the pipeline is in a stable flow. The initial condition is set, the outlet is at atmospheric pressure, and the minimum local pressure drop when the rotor is opened is The water head and flow velocity of each microelement segment at the initial moment are expressed as:

[0126]

[0127] Among them, Q0 is the flow rate in the wellbore at the initial moment;

[0128] S302. During the surface experiment and drilling process, the drilling pump is a multi-cylinder positive displacement pump, and the pumping flow rate is basically stable. After being stabilized by the air cavity, the flow rate can be regarded as a constant. In the transient flow equation, only the negative compatibility equation can be used at the inlet boundary, such as Figure 5 As shown, combined with the boundary conditions of the drilling pump, the boundary flow and pressure head of the drilling pump can be expressed as:

[0129]

[0130] Among them, Q in is the inlet flow rate; A in is the cross-sectional area of ​​the inlet pipe;

[0131] S303, the boundary processing of continuous wave mud pulser is the core part of the whole one-dimensional mathematical model solution, and its boundary conditions are simplified as follows: Figure 6 As shown, due to the continuous wave generated at the pulser, the physical quantities of the left and right nodes of the pulser inside the pipeline are discontinuous, the left side only satisfies the positive compatibility equation, and the right side satisfies the negative compatibility equation. Therefore, it is necessary to solve additional boundary conditions for the left and right nodes of the pulser respectively.

[0132] The left and right sides of the pulser satisfy the conservation of mass and energy, where the conservation of mass means that the node flow rates on the left and right sides are equal:

[0133]

[0134] Among them, the subscripts ML and MR represent the pulser left node and the pulser right node respectively, and M represents the pulser node; Indicates the speed of the node on the left side of the pulser; represents the node velocity on the right side of the pulser; v M Indicates the pulser node speed; A j is the flow area at the pulser;

[0135] The energy on the left and right sides of the pulser is conserved, and its pressure loss is expressed as:

[0136]

[0137] in, Indicates the pressure head on the left side of the pulser; Indicates the pressure head on the right side of the pulser; C d It indicates the throttling coefficient; Indicates the pulser flow rate;

[0138] At the same time, the left and right sides of the pulser satisfy the positive and negative compatibility equations respectively:

[0139]

[0140] The flow velocity at the pulse node is obtained by combining equations (20)-(22):

[0141]

[0142] make The combined equations (20)-(23) are used to calculate the pressure head and flow rate at the left and right nodes of the pulser.

[0143] Finally, in the actual drilling process, the drilling fluid circulates through the annulus to the wellhead blowout preventer, and the outlet is at a constant atmospheric pressure. In the ground experiment, the circulating medium is directly discharged into the water pool through the pipeline and is directly connected to the atmosphere. It is also at a constant atmospheric pressure. The outlet boundary only satisfies the unilateral positive compatibility equation, such as Figure 7 As shown, the outlet boundary flow velocity is solved simultaneously.

[0144]

[0145] Step S4, conduct sensitivity analysis of continuous wave generation signals under different drilling parameters and hydraulic parameters, and use the one-dimensional mathematical model and numerical solution method established in steps S1-S3 to set different drilling parameters (including well depth, well diameter, drill pipe parameters, pulser position, etc.) and hydraulic parameters (drilling fluid density, viscosity, displacement, etc.) to study the influence of continuous wave amplitude and waveform with parameters. Figure 8 As shown, continuous wave signals under different flow rates can be obtained.

[0146] Therefore, the present invention adopts the above-mentioned downhole continuous wave mud pulse signal generation and analysis method, which provides a powerful technical means for quickly analyzing the generation quality and influencing factors of downhole continuous wave signals, can effectively improve the quality of continuous wave signals, and ensure high-speed transmission of logging data.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for analyzing downhole continuous wave mud pulse signals, characterized in that: The following steps are involved: S1. Use transient theory to establish a one-dimensional mathematical model of downhole continuous wave mud pulse generation; the specific model is: S101. Select the wellbore microelement dx through which the drilling fluid flows in the time dt as the control body for analysis, where the flow direction is the positive direction of x, and the angle between the wellbore and the horizontal is θ. According to Euler's transport theorem and the mass conservation theorem, it is calculated that: Among them, m1 and m2 are the masses flowing in and out of the micro-element control body, A is the cross-sectional area in the wellbore, v is the flow velocity of the fluid in the wellbore, ρ is the fluid density, and t is the time; S102. For fluid, the volume elastic coefficient K is: Where P is the fluid pressure. For a uniform circular tube, the relationship between the cross-sectional change rate and the elastic modulus E, the tube wall diameter D and the strain δ is: The ideal wave velocity a of the fluid in the circular tube is: Simplifying the continuity equation, we get: S103, taking the wellbore microelement dx as the research object, performing force analysis on it, and deriving the motion equation as follows: Where g is the acceleration due to gravity, and the wall shear force in steady flow is Substituting into equation (6) and expanding it, we get the following motion equation: Where, f is the friction coefficient; S104. In summary, the one-dimensional mathematical equations for the generation and transmission of continuous waves in the wellbore are obtained: The pressure P is expressed by the pressure head H. Since P = ρg (Hz), and is a second-order small quantity, so formula (8) is simplified to: S2, numerical discretization of nonlinear equations in one-dimensional mathematical models using characteristic line method; Step S2 is specifically as follows: S201. Express equation (9) with L1 and L2 respectively, introduce the real number λ, multiply by L2 and add L1, the sum is still equal to zero: S202. According to the total differential form of the composite function of H and v, let The total differential equation of formula (9) is calculated as: According to equations (11) and (12), we can obtain the positive and negative compatible total differential equation, where along the positive characteristic line: Along the negative characteristic line direction: S203. For the positive and negative compatible equations, a conventional difference grid is constructed. There are three points A, B, and P in the difference grid. The diagonal AP is called the positive characteristic line, and the diagonal BP is called the negative characteristic line. Integrate equations (13) and (14) along the positive characteristic line and the negative characteristic line in the difference grid, respectively, to obtain: Among them, point P represents the unknown parameter at the i-th pipe section at time j, and points A and B represent the known parameters at the i-1 and i+1 pipe sections at time j-1 respectively; H P , H A , H B Represent the pressure head at point P, point A, and point B respectively; v P 、v A 、v B Represent the speeds of point P, point A, and point B respectively; t P ,t A ,t B Respectively represent the time of point P, point A, and point B; S204, Order The velocity and pressure head at point P at time j are obtained as follows: Among them, C P is variable 1; D P is variable 2; C M is variable three; D M is variable four; S3, mathematically characterize the initial drilling conditions and pulser boundary conditions; In step S3, the equations discretized in step S2 are solved in combination with the downhole initial conditions and the boundary conditions of the drilling pump, the pulser, and the outlet blowout preventer, specifically: S301, when the continuous wave pulser is not working, the rotor is in a fully open state. At this time, the flow in the pipeline is in a stable flow. The initial condition is set, the outlet is at atmospheric pressure, and the minimum local pressure drop when the rotor is opened is The water head and flow velocity of each microelement segment at the initial moment are expressed as: Among them, Q0 is the flow rate in the wellbore at the initial moment; Δx is the unit distance, is the pressure head at the outlet at the initial moment; S302. Solve the drilling pump boundary conditions. The drilling pump boundary flow and pressure head are expressed as: Among them, Q in is the inlet flow rate; A in is the cross-sectional area of ​​the inlet pipe; S303, the left and right sides of the pulser satisfy the conservation of mass and energy, where the conservation of mass means that the node flow rates on the left and right sides are equal: Among them, the subscripts ML and MR represent the pulser left node and the pulser right node respectively, and M represents the pulser node; Indicates the speed of the node on the left side of the pulser; represents the node velocity on the right side of the pulser; v M Indicates the pulser node speed; A j is the flow area at the pulser; The energy on the left and right sides of the pulser is conserved, and its pressure loss is expressed as: in, Indicates the pressure head on the left side of the pulser; Indicates the pressure head on the right side of the pulser; C d It indicates the throttling coefficient; Indicates the pulser flow rate; The left and right sides of the pulser satisfy the positive and negative compatibility equations respectively: The flow velocity at the pulse node is obtained by combining equations (19)-(21): make The combined equations (19)-(22) are used to calculate the pressure head and flow rate at the left and right nodes of the pulser; S4. Conduct sensitivity analysis of continuous wave generation signals under different drilling parameters and hydraulic parameters, wherein the drilling parameters include well depth, well diameter, drill pipe parameters and pulser position, and the hydraulic parameters include drilling fluid density, viscosity and displacement.

2. A method for analyzing downhole continuous wave mud pulse signals according to claim 1, characterized in that: In step S4, the one-dimensional mathematical model and numerical solution method established in steps S1-S3 are used to set different drilling parameters and hydraulic parameters, and the influence of the continuous wave amplitude and waveform on the parameters is analyzed to obtain the corresponding continuous wave signal.

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