Method and device for analyzing axial-torsional coupling vibration of drill stem

Abstract

The invention provides a drill stem axial-torsional coupling vibration analysis method and device, and relates to the field of drilling engineering. Establishing a drill bit-rock action model considering friction and cutting actions according to physical and mechanical characteristics of rock crushed by the PDC drill bit; considering the multi-degree-of-freedom characteristic of a drill string system and the action of a near-bit power tool, and establishing a drill string lumped parameter dynamical model with the action of the ground and the near-bit power tool; in combination with a drill bit-rock action model considering friction and cutting actions, a drill column axial-torsion coupling vibration model considering the action of the near-bit power tool is obtained; and analyzing the axial-torsional coupling vibration characteristics of the drill stem under the output of different power tools by utilizing actual data. The model has the beneficial effects that the model can effectively describe the dynamic state of a drill string system in the drilling process, a feasible scheme is provided for deeply understanding the axial-torsion coupling vibration characteristics of the drill string and developing the vibration analysis and suppression research of the drill string in the drilling process, and the model has practicability and applicability.

Description

Technical Field

[0001] The present invention relates to the field of drilling engineering, and in particular to applications in drill bit-rock interaction modeling, multi-dimensional coupled drill string vibration modeling and analysis, and in particular to a drill string axial-torsion coupled vibration analysis method and device. Background Art

[0002] Drilling technology plays a key role in exploration operations. The drill string system is the core of drilling technology. It is usually composed of tools such as a drive device, a drill rod and a drill bit, which are spirally connected in sequence and can extend for thousands of meters. Among them, the polycrystalline diamond compact (PDC) drill bit is the most commonly used drill bit in drilling. As the drilling depth increases, the external force on the drill string system becomes more severe, and various drill string vibration phenomena are very likely to occur, reducing drilling efficiency and damaging the wellbore structure.

[0003] There are three main forms of drill string vibration: lateral vibration, torsional vibration and axial vibration. In the actual drilling process, the drill string system is subject to complex external forces, which causes the movements of the drill string in various dimensions to often affect each other. The vibration phenomena of the drill string in various dimensions often occur simultaneously and couple with each other. With the increase of drilling depth, the operating parameters and the overall stiffness of the drill string system continue to change, and the occurrence characteristics of drill string vibration in various dimensions are also different. Among them, lateral vibration and torsional vibration are most likely to occur. When the drilling depth is large or when encountering alternating soft and hard formations, axial vibration will further occur. Since the rock reaction force on the drill string is mainly in the axial and torsional directions, the axial-torsional vibration of the drill string has received attention.

[0004] Conventional rotary drilling technology will have the problem of low mechanical penetration rate when encountering hard or broken formations. In order to deal with hard formations and reduce the resistance during drilling, power tools are often deployed near the drill bit to provide axial or torsional power. In the axial dimension, near-bit tools such as hydraulic oscillators and downhole impactors are usually deployed near the drill bit. The near-bit tool applies axial drilling pressure to the drill bit, causing the drill bit to impact the rock and drill forward in a rotary impact manner, which can accelerate the rock crushing rate. In the torsional dimension, the most commonly used near-bit power tool is the screw motor. The screw motor is a positive displacement bottom hole power drilling tool. By installing a screw motor in the near-bit drill bit assembly, adjusting the flow and pressure of the drilling fluid output by the mud pump can further control the screw motor torque and speed, and realize the dual power action of the ground and near the drill bit. However, the current drill string vibration model lacks consideration of downhole power tools, and there is a lack of available multi-dimensional coupled drill string vibration model foundation when verifying downhole power tools.

[0005] In summary, the research on the drill string axial-torsional coupled vibration analysis method and device considering the action of the near-bit power tool is of great significance for ensuring the safety and efficiency of the drilling process.

[0006] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0007] The present invention aims to solve the problem that the existing drill string vibration analysis method lacks consideration of the effect of near-drill-bit power tools, and the solution provided is: a drill string axial-torsion coupling vibration analysis method and device are proposed.

[0008] According to a first aspect of the present invention, a drill string axial-torsional coupled vibration analysis method comprises the following steps:

[0009] S1: Establish a drill bit-rock interaction model considering friction and cutting effects;

[0010] S2: Considering the multi-degree-of-freedom characteristics of the drill string system and the action of the near-bit power tool, a concentrated parameter dynamic model of the drill string with the action of the ground and near-bit power tools is established; combined with the drill bit-rock action model considering the friction and cutting action, the axial-torsion coupled vibration model of the drill string considering the action of the near-bit power tool is obtained;

[0011] S3: Based on the established drill string axial-torsional coupled vibration model, actual data are used to consider the effects of near-bit power tools in the axial and torsional dimensions, and the influence of near-bit power tool outputs in different dimensions on the drill string axial-torsional coupled vibration is analyzed through numerical simulation.

[0012] According to a second aspect of the present invention, a drill string axial-torsional coupled vibration analysis device comprises the following units:

[0013] The first modeling unit is used to establish a drill bit-rock interaction model considering friction and cutting effects;

[0014] The second modeling unit is used to consider the multi-degree-of-freedom characteristics of the drill string system and the action of the near-bit power tool, and establish a concentrated parameter dynamic model of the drill string with the action of the ground and the near-bit power tool; combined with the drill bit-rock action model considering the friction and cutting action, establish an axial-torsion coupled vibration model of the drill string considering the action of the near-bit power tool;

[0015] The vibration analysis unit is used to analyze the influence of the output power of the near-bit power tools in different dimensions on the multi-dimensional vibration of the drill string system based on the established drill string axial-torsional coupled vibration model and the actual data, considering the effects of the near-bit power tools in the axial and torsional dimensions.

[0016] According to a third aspect of the present invention, an electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the steps of the drill string axial-torsional coupled vibration analysis method are described.

[0017] According to a fourth aspect of the present invention, a storage medium stores a computer program, which, when executed by a processor, implements the steps of the drill string axial-torsional coupled vibration analysis method.

[0018] The technical solution provided by the present invention has the following beneficial effects:

[0019] The present invention provides a drill string axial-torsion coupling vibration analysis method and device. First, according to the physical and mechanical properties of PDC drill bits in crushing rocks, a drill bit-rock action model considering friction and cutting is established; considering the multi-degree-of-freedom characteristics of the drill string system and the action of near-bit power tools, a drill string concentrated parameter dynamics model with ground and near-bit power tool actions is established; combined with the drill bit-rock action model considering friction and cutting, an axial-torsion coupling vibration model of the drill string considering the action of near-bit power tools is obtained; on this basis, actual data is used to analyze the axial-torsion coupling vibration characteristics of the drill string under different power tool outputs. The beneficial effects of the present invention are: an axial-torsion coupling vibration model of the drill string considering the action of near-bit power tools is established, and the influence of different power tool outputs on the axial-torsion coupling vibration of the drill string is analyzed. The model can effectively characterize the dynamics of the drill string system during drilling, and provides a feasible solution for in-depth understanding of the axial-torsion coupling vibration characteristics of the drill string and conducting research on drill string vibration analysis and suppression during drilling, and is practical and applicable. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0021] Figure 1 is a flow chart of a drill string axial-torsional coupled vibration analysis method according to an embodiment of the present invention;

[0022] Figure 2 is a simplified schematic diagram of the axial-torsion coupling dynamic model of the drill string in an embodiment of the present invention;

[0023] Figure 3 It is the drill bit speed when the axial and torsional outputs of the near-bit power tool are both 0;

[0024] Figure 4 It is the drill bit speed when the axial dimension output of the near-bit power tool is 20KN;

[0025] Figure 5 It is the drill bit speed when the axial dimension output of the near-bit power tool is 40KN;

[0026] Figure 6 is the drill bit speed when the near-bit power tool torsional dimension output is 3000 N·m;

[0027] Figure 7 is the drill bit speed when the near-bit power tool torsional dimension output is 5000 N·m;

[0028] Figure 8 It is a structural diagram of a drill string axial-torsional coupling vibration analysis device in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0030] Embodiment 1:

[0031] Figure 1 This is a flow chart of a drill string axial-torsional coupled vibration analysis method according to an embodiment of the present invention, which specifically includes the following steps:

[0032] S1: Establish a drill bit-rock interaction model considering friction and cutting effects.

[0033] Depending on the purpose of drilling, different drill bits will be selected in the drilling process, and PDC drill bits are the most commonly used drill bits in drilling. According to the physical and mechanical properties of PDC drill bits in crushing rocks, a drill bit-rock interaction model considering friction and cutting is established.

[0034] The rock breaking process of PDC drill bits mainly includes two processes: friction and cutting. The drill bit-rock force and torque are the superposition of the friction component and the cutting component. Under normal circumstances, the calculation formulas for the friction component and the cutting component are as follows:

[0035]

[0036] Where W bf and T bf are the force and torque of the friction process respectively; W bc and T bc are the force and torque of the cutting process respectively; ε is the inherent specific energy of the rock, which is related to the hardness of the rock; R b is the drill bit radius, λ is a constant that characterizes the blade inclination, σ is the rock contact strength, l is the length of the drill bit wear surface, μ is the contact friction coefficient between the drill bit and the rock, γ is a parameter that describes the direction and spatial distribution of the drill bit blade friction contact surface, and d(t) is the sum of the cutting depth of each blade during one rotation of the drill bit.

[0037] Since each blade of the drill bit is basically the same, the instantaneous cutting depth d of each blade is n Basically the same, the axial position z of the blade at the current moment n (t) minus a period of time τ n Previous axial position z n (tt τ ) can get the instantaneous cutting depth d n And the total cutting depth d(t), the formula is as follows:

[0038] d(t)=n b d n , d n =z n (t)-z n (t-τ n ) (2)

[0039] Where t is the current time, n b is the number of blades of the drill bit, τ n is a rotation of 2π / n b The time required, 2π / n b is the angular distance between two adjacent blades, which can be numerically solved according to the following implicit equation:

[0040]

[0041] Where Φ n (t) represents the torsion position of the drill bit at the current moment, Φ n (t-τ n ) represents a time period τ n Previous twist position of the drill bit.

[0042] According to the calculation formula of friction component and cutting component in normal drilling mode in formula (1), the drill bit-rock interaction model considering the combined effect of friction and cutting can be expressed as follows:

[0043]

[0044] In the formula and sgn(·) are the Heaviside function and the sign function, respectively, which are used to judge different operation modes of the drill bit-rock interaction.

[0045] S2: Establish an axial-torsion coupled vibration model of the drill string considering the action of the near-bit power tool. Considering the multi-degree-of-freedom characteristics of the drill string system and the action of the near-bit power tool, a concentrated parameter dynamic model of the drill string with the action of the ground and near-bit power tools is established; combined with the drill bit-rock action model considering friction and cutting, the axial-torsion coupled vibration model of the drill string considering the action of the near-bit power tool is obtained.

[0046] refer to Figure 3 This is a simplified schematic diagram of the drill string axial-torsion coupling dynamic model. The system is regarded as a mass-spring-damper system composed of n units. In this system, each concentrated mass unit has axial motion and torsional motion, and the lateral motion of the concentrated mass unit is ignored. The force conditions of each concentrated mass unit are considered in sections, and the axial drilling pressure W0 and torsional torque T0 of the drill string system are applied to the well drive device part. The axial reaction force W caused by the interaction between the drill bit and the rock is considered in the near-bit drill bit assembly part. b and reaction torque T b .

[0047] The established drill string axial-torsion coupling dynamic model considering the action of the near-bit power tool is as follows:

[0048]

[0049] Where J = diag{J1, J2, L, J n} and M = diag{M1,M2,L,M n} are the diagonal real moment of inertia matrix and mass matrix with n rows and n columns respectively; is the displacement state vector in the axial dimension, Φ(t)=col{Φ1(t),Φ2(t),L,Φ n (t)} represents the displacement state vector in the torsion dimension; C α and K α are the damping coefficient matrix and stiffness coefficient matrix of each dimension, respectively. The subscript α∈{a,t} represents the axial dimension and the torsional dimension, respectively. The stiffness coefficient matrix and damping coefficient matrix of the axial dimension and the torsional dimension have the same form. The specific forms of the stiffness coefficient matrix and damping coefficient matrix of each dimension are as follows:

[0050]

[0051] The right side of formula (6) is the external force acting on each unit, which can be written in vector form as follows:

[0052]

[0053] According to the structural parameters of the drill string system, the moment of inertia J of the above units is i 、Quality M i , axial damping coefficient c ai and the torsional damping coefficient c ti The calculation formula is as follows:

[0054]

[0055] Where L i is the length of each unit, Roi and R ni are the outer and inner diameters of each unit, ρ i is the density of each unit, η and ξ are the damping coefficients in the axial and torsional dimensions, respectively;

[0056] Let the state vector be According to equations (6) and (7), we can obtain the following state space equation:

[0057]

[0058] Where F(t) is the external force vector, u(t) is the input vector of the wellbore, and U T (t) is the downhole power input vector provided by the power tool in the near-bit drill bit assembly.

[0059] For the convenience of analysis, the power input vector of the drill string system is divided into the ground power tool input vector and the near-bit power tool input vector. The axial drilling pressure and torsional torque provided by the near-bit power tool only act on the near-bit drill tool assembly unit, and its form is as follows:

[0060]

[0061] Where W0 and T0 are the axial drilling pressure and torsional torque provided by the uphole part respectively; W TOOL and T TOOL They are the axial drilling pressure and torsional torque provided by the near-bit power tool. The external force vector F(t) is in the form of

[0062]

[0063] In the formula and are the axial and torsional force vectors of the drill string system, They are J n 、M n The reciprocal of .

[0064] A is the system matrix, which is in the following form:

[0065]

[0066] In the formula is a matrix consisting of the inverse of the moment of inertia, is a matrix consisting of the inverse of the mass

[0067]

[0068] At this point, the drill string vibration model can be established according to different drill string system structures and transformed into a state space equation as shown in formula (9) for subsequent numerical simulation analysis.

[0069] S3: Analysis of drill string vibration under different near-bit power tool outputs. Based on the established drill string axial-torsional coupled vibration model, using actual data and considering the effects of near-bit power tools in the axial and torsional dimensions, numerical simulation is used to analyze the effects of near-bit power tool outputs in different dimensions on the drill string axial-torsional coupled vibration.

[0070] For the drill string system with near-bit power tools, near-bit power tools are arranged in the axial and torsional dimensions respectively, and the influence of the output of near-bit power tools in different dimensions on the multi-dimensional vibration of the drill string system is analyzed through numerical simulation. The simulation parameters are given in Table 1.

[0071] Table 1 Simulation parameters

[0072]

[0073] According to the structure of the drill string system, the drill string system is divided into two concentrated mass units. According to equation (9), let the state vector The matrix forms of the state space equations of the axial-torsional coupled vibration model of the drill string system are as follows

[0074]

[0075] First, the influence of different outputs of the axial near-bit power tool on the vibration characteristics is analyzed, and different near-bit axial power is applied to the drill string system to analyze the influence of the near-bit power tool on the axial-torsional coupled vibration of the drill string. The axial near-bit power tool is installed on the drill string system, and axial drilling pressures of 0KN, 20KN, and 40KN are applied respectively to observe its influence on the axial and torsional vibration of the drill string system. The experimental results are as follows: Figures 3 to 5 shown.

[0076] Depend on Figures 3 to 5 It can be seen that when the axial drilling pressure output by the near-bit power tool is 0, the drill string system has periodic synchronous viscosity in both the axial and torsional dimensions. When the near-bit power tool outputs axial drilling pressure to the drill bit, the viscosity of the drill bit in both the axial and torsional dimensions gradually weakens and disappears, and the greater the output power, the faster the viscosity weakens.

[0077] Secondly, the influence of different outputs of the torsional near-bit power tool on the vibration characteristics is analyzed, and different near-bit torsional forces are applied to the drill string system to analyze the influence of the near-bit power tool on the axial-torsional coupled vibration of the drill string. The torsional near-bit power tool is installed on the drill string system, and torsional torques of 0N·m, 3000N·m, and 5000N·m are applied respectively to observe its influence on the torsional and axial vibration of the drill string system. Figure 3 , Figure 6 and Figure 7 shown.

[0078] Figure 3 This is the drill bit speed when the torsional dimension output of the near-bit power tool is 0. At this time, the drill string system has periodic torsional-axial coupled vibration. When the output torque of the near-bit power tool is increased to 3000N·m and 5000N·m, the axial and torsional vibration of the drill string system is as follows: Figure 6 and Figure 7 By comparison, it is found that when the near-bit power tool starts to continuously output constant torsional power, the duration of the axial viscosity of the drill bit gradually decreases, and the greater the output power, the faster the viscosity phenomenon weakens, which is consistent with the results presented by the near-bit power tool in the axial dimension.

[0079] In summary, a near-bit power tool that can output axial drilling pressure and torsional torque is arranged on the drill string system, and the intensity of the axial-torsional coupled vibration of the drill string can be effectively reduced by controlling the output of the near-bit power tool. The greater the output of the near-bit power tool, the weaker the axial-torsional coupled vibration of the drill string.

[0080] Embodiment 2:

[0081] refer to Figure 8 This embodiment provides a drill string axial-torsional coupled vibration analysis device, comprising the following units:

[0082] The first modeling unit 1 is used to establish a drill bit-rock interaction model taking into account friction and cutting effects;

[0083] The second modeling unit 2 is used to combine the drill bit-rock interaction model considering friction and cutting effects, establish the drill string axial-torsion coupling vibration model considering the action of the near-drill bit power tool and convert it into a state space equation form;

[0084] The vibration analysis unit 3 is used to analyze the influence of the near-drill-bit power tool output in different dimensions on the multi-dimensional vibration of the drill string system.

[0085] Embodiment three:

[0086] This embodiment provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the drill string axial-torsional coupled vibration analysis method described in Embodiment 1 when executing the program, and the effect achieved is the same as that of Embodiment 1, which will not be described in detail herein.

[0087] Embodiment 4:

[0088] This embodiment provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the drill string axial-torsional coupled vibration analysis method are implemented. The effect achieved is the same as that of the first embodiment and will not be repeated here.

[0089] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0090] The serial numbers of the embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In a unit claim that lists several means, several of these means may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order and these words may be interpreted as identifiers.

[0091] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A drill string axial-torsional coupled vibration analysis method and device, characterized in that The following steps are involved: S1: Establish a drill bit-rock interaction model considering friction and cutting effects; S2: Considering the multi-degree-of-freedom characteristics of the drill string system and the action of the near-bit power tool, a concentrated parameter dynamic model of the drill string with the action of the ground and near-bit power tools is established; combined with the drill bit-rock action model considering the friction and cutting action, the axial-torsion coupled vibration model of the drill string considering the action of the near-bit power tool is obtained; S3: Based on the established drill string axial-torsional coupled vibration model, actual data are used to consider the effects of near-bit power tools in the axial and torsional dimensions, and the influence of near-bit power tool outputs in different dimensions on the drill string axial-torsional coupled vibration is analyzed through numerical simulation.

2. A drill string axial-torsional coupled vibration analysis method as claimed in claim 1, characterized in that in step S1: In step S1, a drill bit-rock interaction model considering friction and cutting is established according to the physical and mechanical properties of the PDC drill bit in crushing rocks; Where W b and T b are the reaction force and reaction torque caused by the interaction between drill bit and rock; W bc and T bc They are the force and torque of the cutting process respectively; W bf and T bf are the force and torque of the friction process respectively; d(t) is the sum of the cutting depth of each blade during one rotation of the drill bit; represents the first derivative of the torsional position of the drill bit at the current moment; Represents the first derivative of the axial position of the blade at the current moment; and sgn(·) are the Heaviside function and the sign function, respectively, which are used to judge the different operation modes of the drill bit-rock interaction; x represents d(t), one of the.

3. A drill string axial-torsional coupled vibration analysis method and device as claimed in claim 1, characterized in that: In step S2, the process of establishing the drill string axial-torsional coupled vibration model includes: The drill string system is considered as a mass-spring-damper system with n degrees of freedom, and the dynamic equations in axial and torsional dimensions are established; Consider the axial and torsional motions of each concentrated mass unit, and ignore the lateral motion of the concentrated mass unit; The power input vector of the drill string system is divided into the ground power tool input vector and the near-bit power tool input vector. The effect of the near-bit power tool on the drill string system in the lateral dimension when it is in operation is ignored. The axial drilling pressure and torsional torque provided by the near-bit power tool are considered to act only on the near-bit drill tool assembly unit. Establish a concentrated parameter dynamic model of the drill string with the action of surface and near-bit power tools; The drill bit-rock interaction model considering friction and cutting is used to describe the coupling relationship between the axial and torsional motions of the drill string, and the axial-torsional coupled vibration model of the drill string considering the action of the near-bit power tool is obtained jointly.

4. A drill string axial-torsional coupled vibration analysis method and device as claimed in claim 1, characterized in that: In step S2, the formula of the drill string axial-torsional coupled vibration model is: Where, J = diag{J1, J2, …, J n } and M=diag{M1,M2,…,M n } are the diagonal real moment of inertia matrix and mass matrix with n rows and n columns respectively; Z(t)=col{Z1(t),Z2(t),…,Z n (t)} is the displacement state vector in the axial dimension, is the first derivative of the displacement state vector in the axial dimension, is the second derivative of the displacement state vector in the axial dimension; Φ(t)=col{Φ1(t),Φ2(t),…,Φ n (t)} represents the displacement state vector in the torsional dimension, The first derivative of the displacement state vector representing the torsional dimension, The second derivative of the displacement state vector representing the torsional dimension; C α and K α are the damping coefficient matrix and stiffness coefficient matrix of each dimension respectively. The subscript α∈{a,t} represents the axial dimension and torsional dimension respectively. W(t) and T(t) are the vector forms of the external forces in the axial and torsional dimensions respectively.

5. A drill string axial-torsional coupled vibration analysis device, characterized in that: The following units are included: The first modeling unit is used to establish a drill bit-rock interaction model considering friction and cutting effects; The second modeling unit is used to combine the drill bit-rock interaction model considering friction and cutting effects to establish a drill string axial-torsion coupled vibration model considering the action of the near-drill bit power tool; The vibration analysis unit is used to analyze the influence of the near-bit power tool output in different dimensions on the axial-torsional coupled vibration of the drill string.

6. The drill string axial-torsional coupled vibration analysis device according to claim 5, wherein in step S1: In the first modeling unit, based on the physical and mechanical properties of PDC drill bits in crushing rocks, a drill bit-rock interaction model considering friction and cutting is established. The formula is as follows: Where W b and T b are the reaction force and reaction torque caused by the interaction between drill bit and rock; W bc and T bc They are the force and torque of the cutting process respectively; W bf and T bf are the force and torque of the friction process respectively; d(t) is the sum of the cutting depth of each blade during one rotation of the drill bit; represents the first derivative of the torsional position of the drill bit at the current moment; Represents the first derivative of the axial position of the blade at the current moment; and sgn(·) are the Heaviside function and the sign function, respectively, which are used to judge the different operation modes of the drill bit-rock interaction; x represents d(t), one of the.

7. The drill string axial-torsional coupled vibration analysis device according to claim 5, wherein in step S1: In the second modeling unit, the process of establishing the drill string axial-torsional coupled vibration model includes: The drill string system is considered as a mass-spring-damper system with n degrees of freedom, and the dynamic equations in axial and torsional dimensions are established; Consider the axial and torsional motions of each concentrated mass unit, and ignore the lateral motion of the concentrated mass unit; The power input vector of the drill string system is divided into the ground power tool input vector and the near-bit power tool input vector. The effect of the near-bit power tool on the drill string system in the lateral dimension when it is in operation is ignored. The axial drilling pressure and torsional torque provided by the near-bit power tool are considered to act only on the near-bit drill tool assembly unit. Establish a concentrated parameter dynamic model of the drill string with the action of surface and near-bit power tools; The drill bit-rock interaction model considering friction and cutting is used to describe the coupling relationship between the axial and torsional motions of the drill string, and the axial-torsional coupled vibration model of the drill string considering the action of the near-bit power tool is obtained jointly.

8. The drill string axial-torsional coupled vibration analysis device according to claim 5, wherein in step S1: The formula of the drill string axial-torsional coupled vibration model is: Where, J = diag{J1, J2, …, J n } and M=diag{M1,M2,…,M n } are the diagonal real moment of inertia matrix and mass matrix with n rows and n columns respectively; Z(t)=col{Z1(t),Z2(t),…,Z n (t)} is the displacement state vector in the axial dimension, is the first derivative of the displacement state vector in the axial dimension, is the second derivative of the displacement state vector in the axial dimension; Φ(t)=col{Φ1(t),Φ2(t),…,Φ n (t)} represents the displacement state vector in the torsional dimension, The first derivative of the displacement state vector representing the torsional dimension, The second derivative of the displacement state vector representing the torsional dimension; C α and K α are the damping coefficient matrix and stiffness coefficient matrix of each dimension respectively. The subscript α∈{a,t} represents the axial dimension and torsional dimension respectively. W(t) and T(t) are the vector forms of the external forces in the axial and torsional dimensions respectively.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the drill string axial-torsional coupled vibration analysis method according to any one of claims 1 to 4 are implemented.

10. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the drill string axial-torsional coupled vibration analysis method according to any one of claims 1 to 4 are implemented.

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