Method and equipment for suppressing vibration of drill string in drilling process based on modal analysis

Abstract

The invention provides a drilling process drill string vibration suppression method and device based on modal analysis, and relates to the field of geological drilling engineering.The method comprises the steps that S1, a drill string vibration model of a drill string system is constructed, and the drill string vibration model comprises a drill string dynamic model and a drill bit-rock interaction model; s2, performing simulation through a drill bit-rock interaction model to obtain an external interference signal with a multi-modal characteristic, and extracting a main modal frequency of the external interference signal; and S3, based on the drill string dynamic model and the main modal frequency, constructing an active suppression system by adopting an equivalent input interference method, and performing drill string vibration suppression on the drill string system through the active suppression system. The active suppression system is designed based on the drill string dynamic model and the main modal frequency, multi-modal disturbance caused by multi-drilling-tool combination can be eliminated, the stick-slip vibration phenomenon generated in the drilling process is effectively suppressed, and the drilling efficiency can be improved.

Description

Technical Field

[0001] The invention relates to the field of geological drilling engineering, and in particular to a method and equipment for suppressing drill string vibration during drilling based on modal analysis. Background Art

[0002] The drill string system is an important tool for geological drilling. It serves as a hub to connect the drilling rig on the ground and the drill bit in the well, transmit the driving torque on the well to the drill bit at the bottom of the well, and apply pressure to the drill bit to perform rock breaking operations. Therefore, the key to achieving safe and efficient geological drilling lies in how to drive the drill string to move, thereby driving the drill bit to squeeze and twist the rock. As the drilling process continues, the length of the drill string used can reach several thousand meters, but its diameter is often less than 1 meter. Such a large aspect ratio makes the drill string have the physical characteristics of elastic deformation and rigid body motion coupling. Due to this structural characteristic of the drill string, the drill string is very likely to vibrate when driving the drill bit to break the rock, which makes drill string vibration one of the most common and prominent adverse phenomena in the geological drilling process. As the drilling depth gradually increases, the formation changes become more complex, and the drill bit-rock interaction at the bottom of the hole is more and more intense. The influence of these factors often causes drill string vibration phenomena such as stick-slip and drill bit rebound, which seriously affects the drilling efficiency and the service life of the drill tool.

[0003] As the drilling depth increases, the formation changes affect the drill string vibration, showing a complex multi-modal and highly nonlinear motion state, which brings great difficulties to the control of the drilling process. Most existing controllers can only suppress the low-order modes of drill string vibration, and the control effect on the high-order vibration modes of the drill string is average, resulting in the designed controller being unable to eliminate the drill string vibration in the actual deep drilling process. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a method and equipment for suppressing drill string vibration during drilling based on modal analysis, which is used to solve the problem of drill string stick-slip vibration with multi-modal characteristics caused by multiple drill tool combinations, which is common in the current deep geological drilling process.

[0005] The present invention provides a method for suppressing drill string vibration during drilling based on modal analysis, comprising:

[0006] S1: Construct a drill string vibration model of the drill string system. The drill string vibration model includes: a drill string dynamics model and a drill bit-rock interaction model;

[0007] S2: Through the drill bit-rock interaction model, simulate and obtain the external interference signal with multi-modal characteristics, and extract the main modal frequency of the external interference signal;

[0008] S3: Based on the drill string dynamics model and main modal frequencies, an active suppression system is constructed using the equivalent input interference method to suppress the drill string vibration of the drill string system.

[0009] Preferred:

[0010] The expression of the drill string dynamics model is:

[0011]

[0012] in, θ p is the angular position of the top drive with 1 degree of freedom, θ pn is the angular position of the drill rod with n degrees of freedom, θ h is the angular position of the weighted drill rod with 1 degree of freedom, θ d is the angular position of the drill collar with 1 degree of freedom; is the input torque; is the reaction torque on the drill bit; For a given input channel; is the disturbance input channel; C a , J and are the local damping matrix, inertia matrix and torsional stiffness matrix respectively;

[0013] The expression of the drill bit-rock interaction model is:

[0014]

[0015] Among them, W b is the drilling pressure at the drill bit, R b is the drill bit radius, μ b is the dry friction coefficient.

[0016] Preferred:

[0017] Based on the drill string dynamics model, the state space equation from input torque to speed output is constructed, and the state variable x is selected as:

[0018]

[0019] where · represents the first-order derivative with respect to time;

[0020] The state space equation is expressed as:

[0021]

[0022] Among them, x(t) is the state variable function, y(t) is the rotation speed of the top drive, u(t)=T1 is the control input, d(t)=T2 is the external interference signal, and A, B1, B2 and C are all state space matrices.

[0023] Preferably, step S2 specifically comprises:

[0024] S21: The reaction torque of the drill bit-rock interaction model is used as the external disturbance signal of the drill string system;

[0025] S22: Decomposing the external interference signal into K-1 modal components and an unprocessed signal by using a variational mode decomposition method;

[0026] S23: The component with the largest proportion in the modal components is taken as the main mode, and the main modal frequency is extracted.

[0027] Preferred:

[0028] The expression of the external interference signal d(t) is:

[0029]

[0030] Among them, d k (t) is the modal component obtained by decomposition, d u (t) is the unprocessed signal.

[0031] Preferably, step S3 specifically comprises:

[0032] S31: Building an Observer Its expression is:

[0033]

[0034] where · represents the first-order derivative with respect to time, is the equivalent disturbance estimated by the equivalent input disturbance, L is the gain of the observer, K L is the gain factor;

[0035] Solve the observer's parameters based on the linear matrix inequality method;

[0036] S32: Construct a state feedback device, considering the internal model and augmented state of the drill string system Status Feedback It is expressed as:

[0037]

[0038] Among them, u(t) is the control input, d(t) is the external interference signal, A, B1, B2 and C are all state space matrices;

[0039] Solve the parameters of the state feedback device based on the linear quadratic regulator;

[0040] S33: Construct a disturbance estimator, where the expression of the filter F(s) is:

[0041]

[0042] Where T is the time constant;

[0043] Adjust the filter bandwidth so that the disturbance estimator only covers the main mode frequencies of the decomposed disturbance;

[0044] S34: An active suppression system is constructed by the observer, the state feedback device and the disturbance estimator, and the drill string vibration of the drill string system is suppressed by the active suppression system.

[0045] A storage medium stores instructions and data for implementing the method for suppressing drill string vibration during drilling based on modal analysis.

[0046] A drilling process drill string vibration suppression device based on modal analysis includes: a processor and a storage medium; the processor loads and executes instructions and data in the storage medium to implement the drilling process drill string vibration suppression method based on modal analysis.

[0047] The present invention has the following beneficial effects:

[0048] The stick-slip vibration of the drill string is simulated by constructing a drill string dynamics model, the external interference signal is simulated by the drill bit-rock interaction model, the main modal frequency of the external interference signal is extracted using the variational mode decomposition method, and an active suppression system is designed based on the drill string dynamics model and the main modal frequency. This can eliminate the multi-modal disturbance caused by the multi-drill tool combination, effectively suppress the stick-slip vibration phenomenon generated during the drilling process, and improve the drilling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a flow chart of a method according to an embodiment of the present invention;

[0050] Figure 2 This is the external interference signal diagram caused by the interaction between the drill bit and the rock;

[0051] Figure 3 Main mode diagrams extracted by performing two variational mode decompositions for external disturbance signals;

[0052] Figure 4 This is the structure diagram of the active suppression system;

[0053] Figure 5 This is the control effect diagram of the active suppression system;

[0054] Figure 6 This is a structural diagram of the device according to an embodiment of the present invention;

[0055] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0056] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0057] Reference Figure 1 The present invention provides a method for suppressing drill string vibration during drilling based on modal analysis, comprising:

[0058] S1: Construct a drill string vibration model of the drill string system. The drill string vibration model includes: a drill string dynamics model and a drill bit-rock interaction model;

[0059] Furthermore, based on the actual drill string system, in order to better study the stick-slip vibration of the drill string, the dynamic equation of the drill string in the torsional dimension is established; based on the analysis of drill bit rock breaking, a drill bit-rock interaction model is established, and the reaction torque caused by the drill bit-rock interaction is considered as an external interference signal of the drill string system.

[0060] The expression of the drill string dynamics model is:

[0061]

[0062] in, θ p is the angular position of the top drive with 1 degree of freedom, θ pn is the angular position of the drill rod with n degrees of freedom, θ h is the angular position of the weighted drill rod with 1 degree of freedom, θ d is the angular position of the drill collar with 1 degree of freedom; is the input torque; is the reaction torque on the drill bit; For a given input channel; is the disturbance input channel; C a , J and are the local damping matrix, inertia matrix and torsional stiffness matrix respectively;

[0063] The expression of the drill bit-rock interaction model is:

[0064]

[0065] Among them, W b is the drilling pressure at the drill bit, R b is the drill bit radius, μ b is the dry friction coefficient.

[0066] Specifically, the dry friction coefficient can be expressed as:

[0067]

[0068] Ca , J and They can be expressed as:

[0069]

[0070] Based on the relevant content of material mechanics, each item in the matrix is ​​calculated by the following formula:

[0071]

[0072] Where, ∈∈{p1,…,pn,h,d} represents the i-th (i∈1…n) drill pipe unit, weighted drill pipe unit and drill collar; ρ and G s Indicates the density and shear modulus of the drill string; and I ∈ They represent the outer diameter, inner diameter and polar moment of inertia respectively. is the damping coefficient of drilling fluid per unit drill pipe length; the inertia of top drive J p Is a constant value.

[0073] The torsional drill string vibration model is established according to the drilling tool parameters of a well site in Xiangyang, Hubei. The drilling tool parameters are shown in Table 1.

[0074] Table 1 Drill string vibration test simulation parameters

[0075]

[0076] Furthermore, based on the drill string dynamics model, the state space equation from input torque to speed output is constructed, and the state variable x is selected as:

[0077]

[0078] where · represents the first-order derivative with respect to time;

[0079] The state space equation is expressed as:

[0080]

[0081] Among them, x(t) is the state variable function, y(t) is the rotation speed of the top drive, u(t)=T1 is the control input, d(t)=T2 is the external interference signal, and A, B1, B2 and C are all state space matrices.

[0082] Specifically, the top drive and drill collar speeds are The disturbance signal is Figure 2 shown.

[0083] S2: Through the drill bit-rock interaction model, simulate and obtain the external interference signal with multi-modal characteristics, and extract the main modal frequency of the external interference signal;

[0084] Furthermore, step S2 is specifically as follows:

[0085] S21: The reaction torque of the drill bit-rock interaction model is used as the external disturbance signal of the drill string system;

[0086] S22: Decomposing the external interference signal into K-1 modal components and an unprocessed signal by using a variational mode decomposition method;

[0087] S23: The component with the largest proportion in the modal components is taken as the main mode, and the main modal frequency is extracted.

[0088] Furthermore, the expression of the external interference signal d(t) is:

[0089]

[0090] Among them, d k (t) is the modal component obtained by decomposition, d u (t) is the unprocessed signal.

[0091] S3: Based on the drill string dynamics model and main modal frequencies, an active suppression system is constructed using the equivalent input interference method to suppress the drill string vibration of the drill string system.

[0092] Furthermore, an improved equivalent input disturbance method is used to determine the controller parameters based on the modal analysis results. The improved equivalent input disturbance method is used to suppress external disturbances, and the frequency of equivalent disturbances is determined according to the extracted main modal frequencies, thereby improving the estimated disturbance accuracy, suppressing disturbances, and further achieving vibration suppression of the drill string system.

[0093] Step S3 is specifically as follows:

[0094] S31: Building an Observer Its expression is:

[0095]

[0096] where · represents the first-order derivative with respect to time, is the equivalent disturbance estimated by the equivalent input disturbance, L is the gain of the observer, K L is the gain factor;

[0097] Solve the observer's parameters based on the linear matrix inequality method;

[0098] Specifically, the equivalent perturbation of the equivalent input disturbance estimate is It can be expressed as:

[0099]

[0100] Then, the disturbance estimate after filtering by F(s) can be expressed as:

[0101]

[0102] in, and They are and The Laplace transform of

[0103] For the solution of the observer, the linear matrix inequality method is used, and the definition is:

[0104]

[0105] The state space model of the vibration suppression system can be expressed as:

[0106]

[0107] in,

[0108]

[0109] Given 4 positive scalars α, β, χ, γ and a set of feedback control gains K, if there exists a symmetric positive definite matrix;

[0110]

[0111] in,

[0112]

[0113] Satisfies the following inequality

[0114]

[0115] in,

[0116]

[0117] The stability of the closed-loop system can be guaranteed, and the observer gain L and gain factor KL can be expressed as:

[0118] L=-[I 0]P2 -1 W1,

[0119]

[0120] S32: Construct a state feedback device, considering the internal model and augmented state of the drill string system Status Feedback It is expressed as:

[0121]

[0122] Among them, u(t) is the control input, d(t) is the external interference signal, A, B1, B2 and C are all state space matrices;

[0123] Solve the parameters of the state feedback device based on the linear quadratic regulator;

[0124] Specifically, the objective function of the parameter solution of the state feedback device is as follows:

[0125]

[0126] Q=diag{ones(1,10),100,ones(1,10),10},R=1

[0127] The state feedback gain can be expressed as:

[0128]

[0129] Where P can be obtained by the following formula:

[0130]

[0131] S33: Construct a disturbance estimator, where the expression of the filter F(s) is:

[0132]

[0133] Where T is the time constant;

[0134] Adjust the filter bandwidth so that the disturbance estimator only covers the main mode frequencies of the decomposed disturbance;

[0135] Specifically, by analyzing the main modes of the disturbance extracted after decomposition, its frequency is concentrated between 0.0015-1Hz, accounting for 89.5% of the entire vibration signal. The signal diagram of the decomposed external interference signal is as follows: Figure 3 As shown, Figure 3 As shown in (a), after the first decomposition, the main mode still has a certain modal aliasing phenomenon, so a second decomposition is performed to obtain Figure 3 (b),After analysis, it is found that the mode with frequency concentrated between 0.0015-0.22Hz plays a major role, accounting for more than 90%.

[0136] Based on the modal analysis results, the bandwidth of the filter is adjusted so that it only covers the main modal frequencies of the decomposed disturbance. Finally, the disturbance with multi-modal characteristics is suppressed, and the vibration of the drill string is further suppressed.

[0137] S34: An active suppression system is constructed by the observer, the state feedback device and the disturbance estimator, and the drill string vibration of the drill string system is suppressed by the active suppression system.

[0138] Specifically, by following the idea of ​​separation theorem, the stability of the system can be ensured by designing the observer and state feedback separately. The structural diagram of the active suppression system is as follows: Figure 4 shown.

[0139] The final control effect diagram is as follows: Figure 5 As shown in the figure, the system achieves the best control effect at T = 0.7s, the system is out of the sticky state at 15s, and reaches a steady state at 50s. Through the analysis of the simulation results, it is found that in the improved equivalent input interference method, by adjusting the bandwidth of the filter, the control effect can be significantly improved, especially the time to reach a steady state. At the same time, although expanding the filter bandwidth will lead to unsatisfactory overall control effect, it can shorten the time for the drill string to first break away from the sticky stage during the drilling process and reduce the energy accumulation of the drill string, which is also meaningful for reducing the wear of the drill tool.

[0140] See also Figure 6 , Figure 6 4 is a schematic diagram of the working of the hardware device of an embodiment of the present invention, wherein the hardware device specifically comprises: a drill string vibration suppression device 401 during drilling based on modal analysis, a processor 402 and a storage medium 403.

[0141] A drill string vibration suppression device 401 during drilling process based on modal analysis: The drill string vibration suppression device 401 during drilling process based on modal analysis implements the drill string vibration suppression method during drilling process based on modal analysis.

[0142] Processor 402: The processor 402 loads and executes the instructions and data in the storage medium 403 to implement the method for suppressing drill string vibration during drilling based on modal analysis.

[0143] Storage medium 403: The storage medium 403 stores instructions and data; the storage medium 403 is used to implement the method for suppressing drill string vibration during drilling based on modal analysis.

[0144] 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.

[0145] 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.

[0146] 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 method for suppressing drill string vibration during drilling based on modal analysis, characterized in that: include: S1: Construct a drill string vibration model of the drill string system. The drill string vibration model includes: a drill string dynamics model and a drill bit-rock interaction model; S2: Through the drill bit-rock interaction model, simulate and obtain the external interference signal with multi-modal characteristics, and extract the main modal frequency of the external interference signal; S3: Based on the drill string dynamics model and main modal frequencies, an active suppression system is constructed using the equivalent input interference method to suppress the drill string vibration of the drill string system.

2. The method for suppressing drill string vibration during drilling based on modal analysis according to claim 1, characterized in that: The expression of the drill string dynamics model is: in, θ p is the angular position of the top drive with 1 degree of freedom, θ pn is the angular position of the drill rod with n degrees of freedom, θ h is the angular position of the weighted drill rod with 1 degree of freedom, θ d is the angular position of the drill collar with 1 degree of freedom; is the input torque; is the reaction torque on the drill bit; For a given input channel; is the disturbance input channel; C a , J and are the local damping matrix, inertia matrix and torsional stiffness matrix respectively; The expression of the drill bit-rock interaction model is: Among them, W b is the drilling pressure at the drill bit, R b is the drill bit radius, μ b is the dry friction coefficient.

3. The method for suppressing drill string vibration during drilling based on modal analysis according to claim 2, characterized in that: Based on the drill string dynamics model, the state space equation from input torque to speed output is constructed, and the state variable x is selected as: where · represents the first-order derivative with respect to time; The state space equation is expressed as: Among them, x(t) is the state variable function, y(t) is the rotation speed of the top drive, u(t)=T1 is the control input, d(t)=T2 is the external interference signal, and A, B1, B2 and C are all state space matrices.

4. The method for suppressing drill string vibration during drilling based on modal analysis according to claim 1, characterized in that: Step S2 is specifically as follows: S21: The reaction torque of the drill bit-rock interaction model is used as the external disturbance signal of the drill string system; S22: Decomposing the external interference signal into K-1 modal components and an unprocessed signal by using a variational mode decomposition method; S23: The component with the largest proportion in the modal components is taken as the main mode, and the main modal frequency is extracted.

5. The method for suppressing drill string vibration during drilling based on modal analysis according to claim 4, characterized in that: The expression of the external interference signal d(t) is: Among them, d k (t) is the modal component obtained by decomposition, d u (t) is the unprocessed signal.

6. The method for suppressing drill string vibration during drilling based on modal analysis according to claim 1, characterized in that: Step S3 is specifically as follows: S31: Building an Observer Its expression is: where · represents the first-order derivative with respect to time, is the equivalent disturbance estimated by the equivalent input disturbance, L is the gain of the observer, K L is the gain factor; Solve the observer's parameters based on the linear matrix inequality method; S32: Construct a state feedback device, considering the internal model and augmented state of the drill string system Status Feedback It is expressed as: Among them, u(t) is the control input, d(t) is the external interference signal, A, B1, B2 and C are all state space matrices; Solve the parameters of the state feedback device based on the linear quadratic regulator; S33: Construct a disturbance estimator, where the expression of the filter F(s) is: Where T is the time constant; Adjust the filter bandwidth so that the disturbance estimator only covers the main mode frequencies of the decomposed disturbance; S34: An active suppression system is constructed by the observer, the state feedback device and the disturbance estimator, and the drill string vibration of the drill string system is suppressed by the active suppression system.

7. A storage medium, characterized in that: The storage medium stores instructions and data for implementing the method for suppressing drill string vibration during drilling based on modal analysis as described in any one of claims 1 to 6.

8. A drill string vibration suppression device during drilling based on modal analysis, characterized in that: include: A processor and a storage medium; the processor loads and executes instructions and data in the storage medium to implement the method for suppressing drill string vibration during drilling based on modal analysis as described in any one of claims 1 to 6.

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