Underground vibration measurement method and device for rotary steering system

Abstract

The invention discloses an underground vibration measurement method and device for a rotary steering system, and the method comprises the steps: measuring the three-axis acceleration of symmetrical measurement points of a drill column in real time through two acceleration sensor groups which are disposed at the symmetrical positions of the outer wall of a cylindrical circuit skeleton in a guide head; the rotating speed of the guide head is measured in real time through an angular rate gyroscope eccentrically mounted on the outer wall of the cylindrical circuit framework; according to the two groups of three-axis acceleration instantaneous values and rotation speed instantaneous values which are measured in real time, the instantaneous three-axis acceleration and rotation angle acceleration of the rotation guiding head are determined according to the mapping relation between the three-component vibration and rotation speed measurement values of the preset measurement position and the three-component vibration and rotation angle acceleration of the rotation guiding head; and obtaining an underground impact data set based on the instantaneous three-axis acceleration and the rotation angular acceleration of the rotary guide head. Vibration, stick-slip vibration and impact generated in the rotating process of the drilling tool are measured in real time, and the actual situation of underground vibration of the rotary steering system is reflected.

Description

Technical Field

[0001] The present invention relates to the technical field of downhole measurement, and particularly to a downhole vibration measurement method and device for a rotary steerable system. Background Art

[0002] As an international cutting-edge automated drilling technology, the rotary steerable drilling system can provide effective solutions for drilling high-difficulty wells such as ultra-deep wells, high-difficulty directional wells, extended reach wells, and horizontal wells. As the drilling target moves towards deeper and more complex oil and gas reservoirs and unconventional reservoirs, the rotary steerable system faces more complex and harsh downhole working conditions during the drilling process, and the construction difficulty is increasing day by day. Due to the harsh construction environment in the deep well section, the rotary steerable system is usually affected by lateral vibration, longitudinal vibration, torsional vibration, and tangential vibration during the drilling process, and then generates complex forms of vibration such as drill string jumping, stick-slip, and whirling, which have a great impact on the steering ability, steering stability and accuracy, service life of the steering shaft, and wellbore trajectory control of the rotary steerable drill string.

[0003] According to the global failure statistical analysis of Schlumberger in 2014, 75% of downhole complex accidents are attributed to downhole drill string vibration, and the global economic loss caused by downhole vibration reaches up to $300 million per year. To address the above problems, most of the existing technologies use a triaxial acceleration sensor fixed on the axial plane of the outer wall of the drill string, and the accelerations of the X, Y, and Z axes of the drill string can be measured. However, since the rotary steerable system rotates continuously when working downhole, the actual acceleration measurement value also includes a radial acceleration component rω 2 and a tangential acceleration component When the rotation speed of the drill string is low, the radial acceleration component rω 2 and the tangential acceleration component are small and can be ignored; when the drill string rotation speed is high, the radial acceleration component rω 2 and the tangential acceleration component are large, which will affect the judgment of the lateral vibration state.

[0004] Therefore, since the measurement method of the existing technology cannot eliminate the errors representing lateral and tangential vibrations, it is difficult to accurately measure and identify lateral and tangential vibrations. Therefore, in order to effectively reduce the risk of drill string damage and extend the service life of the drill bit, and improve the safety of drilling, it is crucial for the existing technology to establish a downhole vibration measurement scheme for the rotary steerable system. Summary of the Invention

[0005] The present invention aims to establish a downhole vibration measurement method and device for a rotary steerable system in order to effectively reduce the risk of drill string damage and extend the service life of the drill bit, and improve the safety of drilling.

[0006] To solve the above technical problems, an embodiment of the present invention provides a downhole vibration measurement method for a rotary steerable system, including: measuring the three-axis acceleration of symmetric measuring points on the drill string in real time through two groups of acceleration sensor groups symmetrically arranged on the outer wall of a cylindrical circuit framework installed inside the steering head; measuring the rotational speed of the measuring point on the steering head in real time through an angular rate gyro eccentrically installed on the outer wall of the cylindrical circuit framework; determining the instantaneous three-axis acceleration and instantaneous rotational angular acceleration of the rotary steerable head according to the instantaneous values of the two groups of three-axis accelerations and the instantaneous rotational speed measured in real time, and using the mapping relationship between the three-component vibration and rotational speed measurement values at the preset measurement position and the three-component vibration and rotational angular acceleration of the rotary steerable head; obtaining a downhole vibration data set based on the instantaneous three-axis acceleration and instantaneous rotational angular acceleration of the rotary steerable head, and the downhole vibration data set includes but is not limited to: vibration three-component characteristics, stick-slip vibration characteristics, and impact characteristics.

[0007] Preferably, the mapping relationship includes a first relationship between the two groups of three-component vibrations at the symmetric measurement positions and the three-component vibration of the rotary steerable head, and a second relationship between the eccentric rotational speed at the measurement position and the rotational speed of the rotary steerable head. Among them, the first relationship is expressed by the following formula:

[0008]

[0009] Wherein, X 1 and X 2 respectively represent the radial acceleration measurement values at the symmetric positions, Y 1 and Y 2 respectively represent the tangential acceleration measurement values at the symmetric positions, Z 1 and Z 2 respectively represent the axial acceleration measurement values at the symmetric positions, a cx represents the radial acceleration of the rotary steerable head, a cy represents the tangential acceleration of the rotary steerable head, a cz represents the axial acceleration of the rotary steerable head, e represents the radius of the cylindrical circuit framework, ω represents the instantaneous rotational speed of the rotary steerable head; the second relationship is expressed by the following formula:

[0010]

[0011] Wherein, Ω represents the rotational speed of the rotary steerable head, represents the rotational speed measured by the angular rate gyro.

[0012] Preferably, based on the first relationship, the instantaneous three-axis acceleration and instantaneous rotational angular acceleration of the rotary steerable head are determined. Among them, the instantaneous three-axis acceleration and instantaneous rotational angular acceleration of the rotary steerable head are expressed by the following formula:

[0013]

[0014] where a cω represents the angular acceleration of the rotary steering head.

[0015] Preferably, according to the instantaneous triaxial acceleration and the instantaneous angular acceleration of the rotary steering head, vibration three-component characteristics are obtained, including: calculating the radial acceleration characteristic index, the tangential acceleration characteristic index, the axial acceleration characteristic index and the angular acceleration characteristic index within the first unit time according to the instantaneous triaxial acceleration data sequence and the instantaneous angular acceleration sequence; calculating the lateral vibration of the rotary steering head according to the radial acceleration characteristic index and the tangential acceleration characteristic index; calculating the tangential vibration of the rotary steering head according to the angular acceleration characteristic index; and calculating the longitudinal vibration of the rotary steering head according to the axial acceleration characteristic index.

[0016] Preferably, the characteristic index is the root mean square value of the corresponding data sequence within the specified unit time, and the vibration three-component characteristics are calculated by the following expressions:[[]]

[0017]

[0018] where Vib L represents the lateral vibration of the rotary steering head, Vib T represents the tangential vibration of the rotary steering head, Vib Z represents the longitudinal vibration of the rotary steering head, gRMS x represents the root mean square value of the radial acceleration, gRMS y represents the root mean square value of the tangential acceleration, gRMS ω represents the root mean square value of the angular acceleration, gRMS z represents the root mean square value of the axial acceleration.

[0019] Preferably, according to the instantaneous rotational speed of the rotary steering head, instantaneous stick-slip vibration characteristics are obtained, including: calculating a first stick-slip index representing the change amplitude of the rotational speed peak value of the rotary steering head according to the maximum instantaneous rotational speed, the minimum instantaneous rotational speed and the average instantaneous rotational speed of the rotary steering head within the second unit time; calculating a second stick-slip index representing the proportion of the number of measured negative-direction rotational speeds of the rotary steering head according to the total number of rotational speed data and the number of negative-direction rotational speeds of the rotary steering head within the second unit time, where the first stick-slip index and the second stick-slip index are respectively represented by the following expressions:[[]]

[0020]

[0021] where S 1 represents the first stick-slip index, S 2 represents the second stick-slip index, RPM max represents the maximum instantaneous rotational speed within the second unit time, RPM minRepresents the minimum instantaneous rotational speed within the second unit of time, RPM avg Represents the average value of the instantaneous rotational speed within the second unit of time. N represents the total number of measurement points within the second unit of time, and n represents the number of rotational speeds in the negative direction within the second unit of time.

[0022] Preferably, based on the triaxial acceleration of the rotary steering head, the instantaneous impact characteristics are obtained, including: calculating the lateral impact of the rotary steering head according to the instantaneous radial acceleration and the instantaneous tangential acceleration of the rotary steering head; calculating the longitudinal impact of the rotary steering head according to the instantaneous axial acceleration of the rotary steering head, where the lateral impact and the longitudinal impact are respectively represented by the following expressions:

[0023]

[0024] Where, Shock L Represents the lateral impact of the rotary steering head, Shock Z Represents the longitudinal impact of the rotary steering head.

[0025] Preferably, the mapping relationship is obtained in the following way: Analyze the structure of the cylindrical circuit skeleton inside the steering head in the rotary steering system to determine the installation positions of each sensor; Based on the Lagrangian mechanics principle, combined with the installation positions of each sensor, deduce the physical components of the triaxial acceleration value at the target measurement position that the steering head contains, thereby forming a mapping relationship expression for representing each measurement parameter according to the physical components of the steering head. The physical components of the steering head include the physical components for reflecting the vibration and impact in each direction of the steering head and the physical components for reflecting the stick-slip state of the steering head.

[0026] Preferably, the physical components for reflecting the vibration and impact in each direction of the steering head are obtained based on the analysis of the vibration characteristics of the drill string; The physical components for reflecting the stick-slip state of the steering head are obtained based on the analysis of the torsional vibration characteristics of the drill string.

[0027] In addition, an embodiment of the present invention also provides a downhole vibration measurement device for a rotary steering system, including: at least two groups of acceleration sensor groups, which are used to measure the triaxial acceleration of symmetric measurement points on the outer wall of the drill string in real time; an angular rate gyro, which is used to measure the rotational speed of the measurement points of the rotary steering head in real time; a calculation module, which is used to determine the instantaneous triaxial acceleration and the instantaneous rotational angular acceleration of the rotary steering head according to the instantaneous values of the triaxial acceleration of the two groups measured in real time and the instantaneous value of the rotational speed, using the mapping relationship between the three-component vibration and rotational speed measurement values at the preset measurement position and the three-component vibration and rotational angular acceleration of the rotary steering head; a data processing module, which is used to obtain a downhole vibration data set based on the instantaneous triaxial acceleration and the instantaneous rotational angular acceleration of the rotary steering head. The downhole vibration data set includes but is not limited to: vibration three-component characteristics, stick-slip vibration characteristics, impact characteristics.

[0028] Compared with the prior art, one or more embodiments of the above solution may have the following advantages or beneficial effects:

[0029] The present invention provides a downhole vibration measurement method and device for a rotary steerable system. The present invention solves the problem that the downhole vibration and impact parameters cannot be accurately measured during the drilling process of the existing drill string. By using an acceleration sensor group and an angular rate gyroscope symmetrically arranged on the outer wall of a cylindrical circuit skeleton inside the steering head, the radial, tangential, and axial rotational components generated during the rotation of the drill string are solved in real time, and the effective values representing lateral, tangential, longitudinal, and stick-slip vibrations are retained, accurately reflecting the actual situation of downhole vibration and impact of the rotary steerable system. The present invention can effectively reduce the risk of drill string damage and extend the service life of the drill bit, which is of great significance for evaluating the vibration intensity of downhole drill strings and helping technicians identify the working state of downhole drill strings.

[0030] Other features and advantages of the present invention will be described in the following specification, and in part will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the specification, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0032] Figure 1 It is a schematic diagram of the steps of the downhole vibration measurement method for a rotary steerable system according to an embodiment of the present application.

[0033] Figure 2 It is a flowchart of the downhole vibration measurement method for a rotary steerable system according to an embodiment of the present application.

[0034] Figure 3 It is an exemplary diagram of the arrangement of the acceleration sensor group in the downhole vibration measurement method for a rotary steerable system according to an embodiment of the present application.

[0035] Figure 4 It is an exemplary diagram of the arrangement of the angular rate gyroscope in the downhole vibration measurement method for a rotary steerable system according to an embodiment of the present application.

[0036] Figure 5 It is a schematic diagram of the principle of the drill string acceleration components in the wellbore plane in the downhole vibration measurement method for a rotary steerable system according to an embodiment of the present application.

[0037] Figure 6 It is a schematic diagram of the overall structure of the downhole vibration measurement device for a rotary steerable system according to an embodiment of the present application. Detailed Embodiments

[0038] The following will describe in detail the embodiments of the present invention in conjunction with the accompanying drawings and embodiments, so as to fully understand how the present invention uses technical means to solve technical problems and achieve the implementation process of technical effects and implement accordingly. It should be noted that as long as there is no conflict, the various embodiments in the present invention and the various features in each embodiment can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

[0039] In addition, the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0040] The terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "a" and "an" used herein are also intended to include the plural. It should also be understood that the terms "comprising" and / or "including" used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, and do not exclude the presence or addition of one or more other features, integers, steps, operations, units, components, and / or their combinations.

[0041] As an international cutting-edge automated drilling technology, the rotary steerable drilling system can provide effective solutions for the drilling of high-difficulty wells such as ultra-deep wells, high-difficulty directional wells, extended-reach wells, and horizontal wells. As the drilling target moves towards deeper and more complex oil and gas reservoirs and unconventional reservoirs, the rotary steerable system faces more complex and harsh downhole conditions during the drilling process, and the construction difficulty is increasing day by day. Due to the harsh construction environment in the deep well section, the rotary steerable system is usually affected by lateral vibration, longitudinal vibration, torsional vibration, and tangential vibration during the drilling process, and then generates complex forms of vibration such as bit bounce, stick-slip, and whirling, which have a great impact on the steering ability, steering stability and accuracy, service life of the steering shaft, and wellbore trajectory control of the rotary steerable drill string.

[0042] To solve one or more problems in the above-mentioned background art, the present invention proposes a downhole vibration measurement method and device for a rotary steering system. The present invention solves the situation that the downhole vibration and impact parameters cannot be accurately measured during the drilling process of the existing drill string. Through the acceleration sensor group and angular rate gyroscope symmetrically arranged on the outer wall of the cylindrical circuit skeleton inside the steering head, the radial, tangential, and axial rotation components generated by the drill string during rotation are real-time calculated, and the effective values representing lateral, tangential, longitudinal, and stick-slip vibrations are retained, accurately reflecting the actual situation of downhole vibration and impact of the rotary steering system. The present invention can effectively reduce the risk of drill string damage and extend the service life of the drill bit, which is of great significance for evaluating the vibration intensity of downhole drill strings and helping technicians identify the working state of downhole drill strings.

[0043] Example 1

[0044] Figure 1 Schematic diagram of the steps of the downhole vibration measurement method for a rotary steering system according to an embodiment of the present application. Figure 2 Flowchart of the downhole vibration measurement method for a rotary steering system according to an embodiment of the present application. The following combines Figure 1 and Figure 2 , and details the specific process of the downhole vibration measurement method for a rotary steering system disclosed in the embodiments of the present invention.

[0045] Step S110: Through two groups of acceleration sensor groups symmetrically arranged on the outer wall of the cylindrical circuit skeleton inside the steering head, the triaxial accelerations of the symmetric measuring points of the drill string are measured in real time.

[0046] In the embodiment of the present invention, a cylindrical circuit skeleton structure is centrally installed inside the steering head of the rotary steering system. The outer walls on both sides of the cylindrical circuit skeleton are symmetrically windowed, so that the two outer walls are separated by a central angle of 180°. A plane is respectively fixed in the two windows for installing three single-axis acceleration sensors. The vibration and impact conditions received by the steering head can be directly measured by the two groups of acceleration sensor groups.

[0047] Figure 3 Schematic diagram of the arrangement method of the acceleration sensor group in the downhole vibration measurement method for a rotary steering system according to an embodiment of the present application. As Figure 3 shown, the two groups of acceleration sensor groups (six acceleration sensors) inside the steering head of the rotary steering system are arranged symmetrically on the outer wall of the cylindrical circuit skeleton. Each group of acceleration sensor groups will obtain the three-component accelerations at the corresponding skeleton positions, that is, the two groups of acceleration sensor groups will obtain the radial acceleration (X direction), tangential acceleration (Y direction), and axial acceleration (Z direction) at the symmetric positions, and measure the instantaneous values of the triaxial accelerations of the symmetric measuring points of the drill string in real time.

[0048] Step S120: Use an angular rate gyroscopically mounted eccentrically on the outer wall of a cylindrical circuit skeleton to measure the rotational speed of the measurement point of the steering head in real time.

[0049] Figure 4 This is an example diagram of the angular rate gyroscope arrangement in the downhole vibration measurement method for a rotary steering system according to an embodiment of the present application. As Figure 4 shown, there are two symmetric planes installed on the outer wall of the cylindrical circuit skeleton. The angular rate gyroscope is fixed on any one of the planes to measure the rotational speed at the installation position in real time, so as to further obtain the instantaneous rotational speed value of the rotary steering head.

[0050] Step S130: According to the two sets of instantaneous three-axis (three-component) acceleration values and the instantaneous rotational speed value measured in real time, use the mapping relationship between the three-component vibration and rotational speed measurement values at the preset measurement position and the three-component vibration and rotational angular acceleration of the rotary steering head to determine the instantaneous three-axis acceleration and the instantaneous rotational angular acceleration of the rotary steering head. In one embodiment, the above mapping relationship includes: a first relationship between the two sets of three-component vibrations at symmetric measurement positions and the three-component vibrations of the rotary steering head, and a second relationship representing the eccentric rotational speed measurement value at the measurement position and the rotational speed of the rotary steering head.

[0051] In one embodiment, analyze the structure of the cylindrical circuit skeleton inside the steering head in the rotary steering system to determine the installation positions of the sensors; based on the Lagrangian mechanics principle, combined with the installation positions of the sensors, deduce the physical components of the steering head included in the three-axis acceleration value at the target measurement position, so as to form a mapping relationship expression for representing various measurement parameters according to the physical components of the steering head. The physical components of the steering head include: physical components for reflecting the vibrations and impacts in various directions of the steering head and physical components for reflecting the stick-slip state of the steering head. Among them, the physical components for reflecting the vibrations and impacts in various directions of the steering head are obtained based on the analysis of the vibration characteristics of the drill string; the physical components for reflecting the stick-slip state of the steering head are obtained based on the analysis of the torsional vibration characteristics of the drill string.

[0052] Figure 5 This is a schematic diagram of the principle of the drill string acceleration component in the wellbore plane in the downhole vibration measurement method for a rotary steering system according to an embodiment of the present application. In the embodiment of the present invention, based on the structure of the cylindrical circuit skeleton centrally installed inside the steering head, the installation position of the sensor is determined to be the outer wall of the cylindrical skeleton. According to this installation method, the acceleration sensor model can refer to Figure 5 the acceleration component diagram of the drill string in the wellbore plane. Based on the Lagrangian mechanics principle, the radial and tangential accelerations at the measurement position can be expressed by the following expressions:

[0053]

[0054] where, a GRepresents the acceleration at the eccentric position G point; Represents the radial acceleration in the cylindrical coordinate system; Represents the tangential acceleration in the cylindrical coordinate system; Represents the revolution centrifugal acceleration; Represents the Coriolis acceleration; eω 2 Represents the rotation centrifugal acceleration; Represents the angular acceleration of rotation; r represents the radial displacement; Represents the revolution angle; ω represents the rotational speed; e represents the distance from the measurement point to the center; t represents time; i represents the unit vector in the X-axis direction; j represents the unit vector in the Y-axis direction.

[0055] Furthermore, when transforming formula (1) into the Cartesian coordinate points, it can be expressed by the following expressions:

[0056]

[0057] Furthermore, it can be known from formula (2) that the acceleration at the measurement point G includes: the acceleration caused by the translation and revolution of the drill string and the acceleration caused by the eccentricity and rotation of the measurement point. Therefore, formula (2) can be simplified to the following expressions:

[0058]

[0059] Among them, a cx Represents the radial acceleration at the center of the rotary steering head; a cy Represents the tangential acceleration at the center of the rotary steering head. From formula (3), the physical components included in the triaxial acceleration and single-axis rotational speed at the measurement position are deduced. The mapping relationship between the three-component vibration and rotational speed measurement values at the measurement position and the three-component vibration and rotational speed of the rotary steering head can be expressed by the following expressions:

[0060]

[0061] Among them, X a Represents the radial acceleration at the measurement position; Y a Represents the tangential acceleration at the measurement position; Z a Represents the axial acceleration at the measurement position; Ω represents the rotational speed of the rotary steering head; a cz Represents the axial acceleration at the center of the rotary steering head; Represents the rotational speed measured by the angular rate gyro.

[0062] In an embodiment of the present invention, based on the vibration characteristics of the drill string, physical components reflecting the vibrations in all directions of the rotary steering head are determined. Among them, the lateral vibration is represented by the radial acceleration and tangential acceleration of the rotary steering head, the tangential vibration is represented by the angular acceleration of rotation at the eccentric position, and the longitudinal vibration is represented by the axial acceleration. Based on this, a six-acceleration sensor arrangement scheme with eccentric symmetry is determined to measure the radial acceleration, tangential acceleration, and axial acceleration at symmetric positions of the cylindrical circuit skeleton. The mapping relationship between the three-component vibration at the measurement position and the three-component vibration of the rotary steering head is the first relationship, as follows:

[0063]

[0064] Wherein, X 1 and X 2 respectively represent the measured values of the radial acceleration at the symmetric position, Y 1 and Y 2 respectively represent the measured values of the tangential acceleration at the symmetric position, and Z 1 and Z 2 respectively represent the measured values of the axial acceleration at the symmetric position.

[0065] Furthermore, based on the torsional vibration characteristics of the drill string, the physical component reflecting the stick-slip state of the rotary steering head, that is, the rotational speed of the rotary steering head, is determined. Thus, an eccentric angular rate gyro arrangement scheme is determined, and the mapping relationship between the measured rotational speed at the measurement position and the rotational speed of the rotary steering head is the second relationship, as follows:

[0066]

[0067] Step S140: Based on the instantaneous three-axis acceleration and instantaneous rotational speed of the rotary steering head obtained in step S130, an underground vibration data set is obtained.

[0068] In an embodiment of the present invention, the underground vibration data set includes vibration three-component characteristics. Among them, according to the instantaneous three-axis acceleration and instantaneous rotational speed of the rotary steering head, the underground vibration three-component characteristics are obtained. It includes: according to the instantaneous three-axis acceleration data sequence and the instantaneous angular acceleration of rotation sequence, calculating the radial acceleration characteristic index, tangential acceleration characteristic index, axial acceleration characteristic index, and angular acceleration of rotation characteristic index within each first unit time; according to the radial acceleration characteristic index and the tangential acceleration characteristic index, calculating the lateral vibration of the rotary steering head; according to the angular acceleration of rotation characteristic index, calculating the tangential vibration of the rotary steering head; and according to the axial acceleration characteristic index, calculating the longitudinal vibration of the rotary steering head.

[0069] Specifically, according to formula (5), the expressions for the radial acceleration, tangential acceleration, axial acceleration, and angular acceleration of rotation at the center of the rotary steering head can be obtained as follows:

[0070]

[0071] where a cω represents the rotational angular acceleration of the rotary steering head.

[0072] In an embodiment of the present invention, a measurement frequency of 500 Hz is selected to sample six eccentric symmetric acceleration sensors, and a preset measurement period is 1 second, which is the first unit of time. 500 sampling point values of the six acceleration sensors within the first unit of time are obtained, and the radial acceleration, tangential acceleration, axial acceleration, and rotational angular acceleration of the rotary steering head are calculated and represented using formula (6).

[0073] Furthermore, the root mean square values of the radial acceleration, tangential acceleration, axial acceleration, and rotational angular acceleration of the rotary steering head within the first unit of time are calculated. Based on the root mean square values of the radial acceleration and tangential acceleration, the lateral vibration characteristics are calculated. Based on the root mean square value of the rotational angular acceleration, the tangential vibration characteristics are calculated. Based on the root mean square value of the axial acceleration, the longitudinal vibration characteristics are calculated. Among them, the three-component characteristics of downhole vibration are calculated using the following expressions:

[0074]

[0075] where Vib L represents lateral vibration; Vib T represents tangential vibration; Vib Z represents longitudinal vibration; gRMS x represents the root mean square value of the radial acceleration within the first unit of time; gRMS y represents the root mean square value of the tangential acceleration within the first unit of time; gRMS ω represents the root mean square value of the rotational acceleration within the first unit of time; gRMS z represents the root mean square value of the axial acceleration within the first unit of time.

[0076] Furthermore, the downhole vibration data set also includes stick-slip vibration characteristics. Among them, according to the instantaneous rotational speed of the rotary steering head, the instantaneous stick-slip vibration characteristics are obtained. It includes: calculating a first stick-slip index that characterizes the change amplitude of the rotational speed peak value of the rotary steering head according to the maximum instantaneous rotational speed, minimum instantaneous rotational speed, and average instantaneous rotational speed of the rotary steering head within the second unit of time measurement period; calculating a second stick-slip index that characterizes the proportion of the number of measurements of the negative-direction rotational speed of the rotary steering head according to the total number of rotational speed data and the number of negative-direction rotational speeds of the rotary steering head within the second unit of time measurement period.

[0077] In an embodiment of the present invention, based on the rotational speed measured by an eccentric angular rate gyroscope, a stick-slip vibration characteristic is determined. Among them, the sampling frequency of the angular rate gyroscope is set to 80 Hz, and the preset measurement period is 7.5 seconds, which is the second unit of time. Within the second unit of time, 600 angular rate gyroscope sampling data are obtained. Further, based on the maximum value, minimum value, average value of the sampling data within the measurement period, and the number of negative-direction rotational speeds, the stick-slip vibration characteristic is calculated. The stick-slip vibration is represented by a first stick-slip index and a second stick-slip index. Among them, the first stick-slip index and the second stick-slip index are calculated using the following expressions:

[0078]

[0079] Among them, S 1 represents the first stick-slip index, which is used to represent the change amplitude of the rotational speed peak value. The larger the value, the stronger the stick-slip vibration; S 2 represents the second stick-slip index, which is used to represent the proportion of the number of negative-direction rotational speeds. Under normal circumstances, it is 0; RPM max represents the maximum instantaneous rotational speed within a measurement period; RPM min represents the minimum instantaneous rotational speed within the second unit of time; RPM avg represents the average rotational speed within the second unit of time; N represents the number of measurement points within the second unit of time; n represents the number of negative-direction rotational speeds.

[0080] Further, the downhole vibration data set further includes an impact characteristic. According to the triaxial acceleration of the rotary steerable head, an instantaneous impact characteristic is obtained. It includes: calculating the lateral impact of the rotary steerable head according to the instantaneous radial acceleration and instantaneous tangential acceleration of the rotary steerable head; calculating the longitudinal impact of the rotary steerable head according to the instantaneous axial acceleration of the rotary steerable head.

[0081] In an embodiment of the present invention, based on the radial acceleration, tangential acceleration, and axial acceleration measured at the center of the rotary steerable head by an eccentric symmetric acceleration sensor, an impact characteristic is determined, including: a lateral impact characteristic and a longitudinal impact characteristic. Among them, the lateral impact is represented by the transient measurement values of the radial acceleration and the tangential acceleration, and the longitudinal impact is represented by the transient measurement value of the axial acceleration. Thus, the impact characteristic can be calculated through the following expressions:

[0082]

[0083] Among them, Shock L is the lateral impact; Shock Z is the longitudinal impact.

[0084] Example 2

[0085] Based on the downhole vibration measurement method for a rotary steerable system described in the above-mentioned Embodiment 1, the present invention also provides a downhole vibration measurement device for a rotary steerable system. This device is used to implement the downhole vibration measurement method for a rotary steerable system described in the above-mentioned Embodiment 1.

[0086] Figure 6 It is a schematic structural diagram of the downhole vibration measurement device for a rotary steerable system according to an embodiment of the present application. As Figure 6 shown, the device described in the embodiment of the present invention includes: an acceleration sensor group 601, an angular rate gyro 602, a solution module 603, and a data processing module 604.

[0087] Specifically, the acceleration sensor group 601 is implemented according to the method described in the above step S110. The number of the acceleration sensor group is at least two groups, and it is configured to measure the three-axis accelerations of symmetric measuring points on the outer wall of the drill string in real time; the angular rate gyro 602 is implemented according to the method described in the above step S120, and it is configured to measure the rotational speed of the measuring point of the rotary steerable head in real time; the solution module 603 is implemented according to the method described in the above step S130, and it is configured to determine the instantaneous three-axis acceleration and the instantaneous rotational angular acceleration of the rotary steerable head according to the instantaneous values of the two groups of three-axis accelerations and the instantaneous value of the rotational speed measured in real time, by using the mapping relationship between the three-component vibration and rotational speed measurement values at the preset measurement position and the three-component vibration and rotational angular acceleration of the rotary steerable head; the data processing module 604 is implemented according to the method described in the above step S140, and it is configured to obtain a downhole vibration data set based on the instantaneous three-axis acceleration and the instantaneous rotational angular acceleration of the rotary steerable head. The downhole vibration data set includes, but is not limited to: vibration three-component characteristics, stick-slip vibration characteristics, and impact characteristics.

[0088] The present invention discloses a downhole vibration measurement method and device for a rotary steerable system. The present invention solves the situation that the downhole vibration and impact parameters cannot be accurately measured during the drilling process of the existing drill string. By the acceleration sensor group and the angular rate gyro installed at the symmetric positions on the outer wall of the cylindrical circuit skeleton inside the steerable head, the radial, tangential, and axial rotational components generated during the rotation of the drill string are solved in real time, and the effective values representing the lateral, tangential, longitudinal, and stick-slip vibrations are retained, accurately reflecting the actual situation of the downhole vibration and impact of the rotary steerable system. The present invention can effectively reduce the risk of drill string damage and extend the service life of the drill bit, and is of great significance for evaluating the downhole drill string vibration intensity and helping technicians identify the working state of the downhole drill string.

[0089] As described above, it is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

[0090] In the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0091] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0092] It should be understood that the embodiments disclosed by the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should extend to equivalent alternatives of these features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are only for the purpose of describing specific embodiments and do not mean to limit.

[0093] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in connection with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" that appear throughout the specification do not necessarily all refer to the same embodiment.

[0094] Although the disclosed embodiments of the present invention are as above, the content described is only the embodiment adopted for the convenience of understanding the present invention and is not used to limit the present invention. Any person skilled in the art within the technical field to which the present invention pertains can make any modifications and changes in the form of implementation and details without departing from the spirit and scope disclosed by the present invention. However, the patent protection scope of the present invention shall still be subject to the scope defined by the appended claims.

Claims

1. A downhole vibration measurement method for a rotary steerable system, characterized in that: include: The three-axis acceleration of the symmetrical measuring points of the drill string is measured in real time by two groups of acceleration sensors installed at symmetrical positions on the outer wall of the cylindrical circuit frame inside the guide head; The rotation speed of the guide head measuring point is measured in real time by using an angular rate gyro eccentrically installed on the outer wall of the cylindrical circuit frame; According to the two sets of instantaneous values ​​of three-axis acceleration and instantaneous values ​​of rotation speed measured in real time, the instantaneous three-axis acceleration and instantaneous rotational angular acceleration of the rotating guide head are determined by using the mapping relationship between the three-component vibration and rotational speed measurement values ​​of the preset measuring position and the three-component vibration and rotational angular acceleration of the rotating guide head; Based on the instantaneous three-axis acceleration and the instantaneous rotational angular acceleration of the rotary guide head, a downhole vibration data group is obtained, and the downhole vibration data group includes but is not limited to: vibration three-component characteristics, stick-slip vibration characteristics, and impact characteristics.

2. The downhole vibration measurement method according to claim 1, characterized in that: The mapping relationship includes a first relationship between two groups of three-component vibrations at symmetrical measurement positions and the three-component vibrations of the rotating guide head, and a second relationship between the eccentric rotation speed at the measurement position and the rotation speed of the rotating guide head, wherein the first relationship is expressed by the following expression: Among them, X1 and X2 represent the radial acceleration measurement values ​​at the symmetrical positions, Y1 and Y2 represent the tangential acceleration measurement values ​​at the symmetrical positions, Z1 and Z2 represent the axial acceleration measurement values ​​at the symmetrical positions, and a cx represents the radial acceleration of the rotating guide head, a cy is the tangential acceleration of the rotating guide head, a cz represents the axial acceleration of the rotating guide head, e represents the radius of the cylindrical circuit skeleton, and ω represents the instantaneous rotation speed of the rotating guide head; The second relationship is expressed by the following expression: Where, Ω represents the rotation speed of the rotary guide head, Indicates the angular rate gyro measures the rotational speed.

3. The downhole vibration measurement method according to claim 2, characterized in that: Based on the first relationship, the instantaneous three-axis acceleration and the instantaneous rotational angular acceleration of the rotating guide head are determined, wherein the instantaneous three-axis acceleration and the instantaneous rotational angular acceleration of the rotating guide head are expressed by the following expressions: Among them, a cω Indicates the angular acceleration of the rotating guide head.

4. The downhole vibration measurement method according to any one of claims 1 to 3, characterized in that: According to the instantaneous three-axis acceleration and instantaneous rotational angular acceleration of the rotating guide head, the three-component vibration characteristics are obtained, which include: Calculating the radial acceleration characteristic index, the tangential acceleration characteristic index, the axial acceleration characteristic index and the angular acceleration characteristic index in the first unit time according to the instantaneous three-axis acceleration data sequence and the instantaneous angular acceleration sequence; calculating the lateral vibration of the rotary guide head according to the radial acceleration characteristic index and the tangential acceleration characteristic index; Calculating the tangential vibration of the rotating guide head according to the rotational angular acceleration characteristic index; The longitudinal vibration of the rotary guide head is calculated according to the axial acceleration characteristic index.

5. The downhole vibration measurement method according to claim 4, characterized in that: The characteristic index is the root mean square value of the corresponding data sequence in a specified unit time, wherein the vibration three-component characteristics are calculated using the following expression: Among them, Vib L Indicates the lateral vibration of the rotating guide head, Vib T Indicates the tangential vibration of the rotating guide head, Vib Z represents the longitudinal vibration of the rotating guide head, gRMS x Indicates the root mean square value of radial acceleration, gRMS y Represents the root mean square value of tangential acceleration, gRMS ω Indicates the root mean square value of the angular acceleration, gRMS z It represents the RMS value of axial acceleration.

6. The downhole vibration measurement method according to any one of claims 1 to 5, characterized in that: According to the instantaneous rotation speed of the rotating guide head, the instantaneous stick-slip vibration characteristics are obtained, including: Calculating a first stick-slip index representing a variation range of a peak value of a rotational speed of the rotational guide head according to a maximum instantaneous rotational speed, a minimum instantaneous rotational speed and an average value of the instantaneous rotational speed of the rotational guide head within a second unit time; According to the total number of rotation speed data and the number of negative rotation speeds of the rotating guide head in the second unit time, a second stick-slip index characterizing the proportion of the number of measurements of the negative rotation speed of the rotating guide head is calculated, wherein the first stick-slip index and the second stick-slip index are respectively expressed by the following expressions: Where S1 represents the first stick-slip index, S2 represents the second stick-slip index, RPM max Indicates the maximum instantaneous speed in the second unit time, RPM min Indicates the minimum instantaneous speed in the second unit time, RPM avg It represents the instantaneous average speed in the second unit time, N represents the total number of measuring points in the second unit time, and n represents the number of negative speeds in the second unit time.

7. The downhole vibration measurement method according to any one of claims 1 to 6, characterized in that: According to the three-axis acceleration of the rotating guide head, the instantaneous impact characteristics are obtained, including: Calculate the lateral impact of the rotating guide head according to the instantaneous radial acceleration and the instantaneous tangential acceleration of the rotating guide head; According to the instantaneous axial acceleration of the rotating guide head, the longitudinal impact of the rotating guide head is calculated, wherein the lateral impact and the longitudinal impact are respectively expressed by the following expressions: Among them, Shock L Indicates the lateral impact of the rotating guide head, Shock Z Indicates the longitudinal impact of the rotating guide head.

8. The downhole vibration measurement method according to any one of claims 1 to 7, characterized in that: The mapping relationship is obtained in the following way: Analyze the structure of the cylindrical circuit skeleton inside the guide head of the rotary guide system and determine the installation position of each sensor; Based on the principle of Lagrangian mechanics and in combination with the installation positions of the sensors, the physical components of the guide head contained in the three-axis acceleration values ​​at the target measurement position are derived, thereby forming a mapping relationship expression for representing various measurement parameters according to the physical components of the guide head. The physical components of the guide head include physical components for reflecting the vibration and impact of the guide head in various directions and physical components for reflecting the stick-slip state of the guide head.

9. The downhole vibration measurement method according to claim 8, characterized in that: The physical components used to reflect the vibration and impact of the guide head in various directions are obtained based on the analysis of the vibration characteristics of the drill string; The physical component used to reflect the stick-slip state of the guide head is obtained based on the analysis of the torsional vibration characteristics of the drill string.

10. A downhole vibration measuring device for a rotary steering system, characterized in that: The downhole vibration measuring device is implemented by using the downhole vibration measuring method according to any one of claims 1 to 9, wherein the downhole vibration measuring device comprises: At least two groups of acceleration sensors, which are used to measure the three-axis acceleration of symmetrical measuring points on the outer wall of the drill string in real time; Angular rate gyro, which is used to measure the rotation speed of the measuring point of the rotating guide head in real time; A solution module is used to determine the instantaneous three-axis acceleration and instantaneous rotational angular acceleration of the rotary guide head according to two sets of instantaneous three-axis acceleration values ​​and instantaneous rotational speed values ​​measured in real time, using the mapping relationship between the three-component vibration and rotational speed measurement values ​​of the preset measurement position and the three-component vibration and rotational angular acceleration of the rotary guide head; A data processing module is used to obtain a downhole vibration data set based on the instantaneous three-axis acceleration and instantaneous rotational angular acceleration of the rotating guide head, wherein the downhole vibration data set includes but is not limited to: vibration three-component characteristics, stick-slip vibration characteristics, and impact characteristics.

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