Downhole bit pressure and torque measurement method and system

Abstract

The present application discloses a downhole WOB and torque measurement method and system, which relates to the field of drilling measurement. The method sets vibration measurement sensors at both ends of the drill collar; during the drilling process, the axial acceleration and tangential acceleration of the two ends of the drill collar are measured in real time by the vibration measurement sensors; the axial relative displacement between the two end sections of the drill collar is calculated based on the axial acceleration at both ends of the drill collar; the relative angular displacement between the two end sections of the drill collar is calculated based on the tangential acceleration at both ends of the drill collar; based on the axial relative displacement between the two end sections of the drill collar, the WOB experienced by the drill collar is obtained by using the relationship between WOB and axial relative displacement; based on the relative angular displacement between the two end sections of the drill collar, the torque experienced by the drill collar is obtained by using the relationship between torque and relative angular displacement. The present application proposes a new WOB and torque measurement method, which is simple to operate, has strong anti-interference performance, and can improve the measurement stability and adaptability of downhole WOB and torque.

Description

Technical Field

[0001] The present application relates to the field of drilling measurement, and in particular to a downhole weight-on-bit and torque measurement method and system. Background Art

[0002] With the rapid development of the oil and gas industry and the deepening of exploration and development, surface resource extraction is declining, and exploration is gradually shifting to deeper formations. However, the complex geological environment at deep depths makes drilling prone to problems such as stick-slip vibration, drill jumping, and sudden rotation, leading to drill bit tooth breakage and torsional deformation of drill tools. This seriously impacts drilling efficiency and tool life, extending drilling cycles and significantly increasing costs. Real-time measurement of drilling parameters such as weight on bit and torque near the drill bit can effectively prevent these accidents and provide technical support for safe and efficient drilling.

[0003] Measuring downhole WOB and torque enables drillers to more accurately control the drilling process, reduce drilling risks, and improve the observability and controllability of exploratory wells. However, downhole conditions are complex, and the harsh environment of high temperature and high pressure can interfere with the accuracy of torque and WOB measurements. Currently, downhole torque measurement is primarily based on the strain gauge measurement principle, using different strain gauge materials to measure WOB and torque. Measurement errors are reduced through data processing, using different methods of attaching strain gauges, adding pressure sensors, and temperature sensors. However, drill tools experience severe vibration downhole, making them prone to buckling and deformation. Furthermore, high downhole temperatures can affect the stability of strain gauges. Summary of the Invention

[0004] The purpose of this application is to provide a downhole bit weight and torque measurement method and system, which can improve the measurement stability and adaptability of downhole bit weight and torque.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides a downhole drilling pressure and torque measurement method, comprising: respectively setting vibration measurement sensors at both ends of a drill collar; establishing a relationship between drilling pressure and axial relative displacement; establishing a relationship between torque and relative angular displacement; during the drilling process, measuring the vibration acceleration at both ends of the drill collar in real time by means of the vibration measurement sensor; the vibration acceleration comprises axial acceleration and tangential acceleration; calculating the axial relative displacement between the two end sections of the drill collar according to the axial acceleration at both ends of the drill collar; calculating the relative angular displacement between the two end sections of the drill collar according to the tangential acceleration at both ends of the drill collar; obtaining the drilling pressure on the drill collar by using the relationship between drilling pressure and axial relative displacement based on the axial relative displacement between the two end sections of the drill collar; obtaining the torque on the drill collar by using the relationship between torque and relative angular displacement based on the relative angular displacement between the two end sections of the drill collar.

[0007] In a second aspect, the present application provides a downhole drilling pressure and torque measurement system, comprising: a drill tool, a computer and two vibration measurement sensors; the two vibration measurement sensors are respectively arranged at the two ends of the drill collar of the drill tool in a one-to-one correspondence; during drilling using the drill tool, the two vibration measurement sensors are used to measure the axial acceleration and tangential acceleration at both ends of the drill collar in real time; the computer is used to establish a relationship between drilling pressure and axial relative displacement and a relationship between torque and relative angular displacement, and to receive the axial acceleration and rotational speed at both ends of the drill collar, and calculate the axial relative displacement between the two end sections of the drill collar according to the axial acceleration at both ends of the drill collar; calculate the relative angular displacement between the two end sections of the drill collar according to the tangential acceleration at both ends of the drill collar; based on the axial relative displacement between the two end sections of the drill collar, use the relationship between drilling pressure and axial relative displacement to obtain the drilling pressure on the drill collar; based on the relative angular displacement between the two end sections of the drill collar, use the relationship between torque and relative angular displacement to obtain the torque on the drill collar.

[0008] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0009] The present application provides a method and system for measuring downhole weight-on-bit and torque. The vibration measurement sensor is a high-frequency measurement sensor. When measuring downhole vibration data, it is not affected by downhole vibration conditions and the harsh environment of high temperature and high pressure downhole. It can accurately measure vibration acceleration, and then solve the axial relative displacement and relative angular displacement through vibration acceleration. Based on the established relationship between weight-on-bit and axial relative displacement and the relationship between torque and relative angular displacement, the weight-on-bit and torque exerted on the drill collar are calculated, thereby improving the measurement stability and adaptability of downhole weight-on-bit and torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0011] Figure 1 Schematic diagram of changes caused by a drill collar subjected to a torsional force in one embodiment of the present application;

[0012] Figure 2 Schematic diagram of changes in two cross sections of a drill collar when subjected to torsional force in one embodiment of the present application;

[0013] Figure 3 Schematic diagram of the deformation of a drill collar under drilling pressure in one embodiment of the present application;

[0014] Figure 4 This is a force analysis diagram of any two cross sections of a flexible cylinder in an embodiment of the present application;

[0015] Figure 5 A torsion analysis diagram provided for another embodiment of the present application;

[0016] Figure 6 A schematic diagram of a vibration measurement sub connection provided in another embodiment of the present application;

[0017] Figure 7 A schematic diagram of the design structure of a first vibration measurement sub provided in another embodiment of the present application;

[0018] Figure 8 A schematic diagram of the design structure of a second vibration measurement sub provided in another embodiment of the present application;

[0019] Figure 9 A simplified flowchart of a downhole weight-on-bit and torque measurement method provided in one embodiment of the present application.

[0020] Reference numerals:

[0021] First vibration measuring sub-1, drill collar-2, second vibration measuring sub-3, sub-body-4, cover plate-5, sensor integrated unit-6, accommodating chamber-7. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0023] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0024] Figure 1 Shows the changes in the drill collar when it is subjected to torsional force. Figure 2 Part (a) and Figure 2 Part (b) shows the changes in the two cross sections of the drill collar when subjected to torsional force. Figure 3 The drill collar is a flexible cylinder, based on the Figures 1 to 3 The force deformation of the drill collar shown in the figure analyzes and measures the movement of the flexible cylinder: studies the motion equation of the relative motion between any two sections O1 and O2 of the same cylinder.

[0025] (1) Through the relevant mechanism of flexible cylinder, such as Figure 4 As shown, the changes in physical quantities during relative rotation between any two cross sections of a flexible cylinder are analyzed.

[0026]

[0027] Where J is the moment of inertia between the two sections, C is the damping coefficient, K is the torsional stiffness, and θ is the instantaneous angle. The dynamic torque measurement model is obtained by subtracting Equations (1) and (2), as shown in Equation (3).

[0028]

[0029] The moment between the two sections generates torque deformation during the transmission process. The flexible cylinder section O1 rotates by an angle θ1, and the section O2 rotates by an angle θ2. As a result, the difference in the two rotation angles θ causes shear strain in the unit. At the same time, the acceleration and velocity of the two sections also change.

[0030] (2) The flexible cylinder changes uniformly when subjected to force. Analyze the changes in physical quantities when axial relative motion occurs between the two cross sections when subjected to force.

[0031]

[0032] Where F is the axial force between the two sections, m is the mass, D is the damping coefficient, k is the stiffness, and y is the instantaneous displacement. When the ends of the flexible cylinder are stretched or compressed, the relative axial positions of the two sections change. When considering the relative displacement, the equation can be transformed into Equation (5).

[0033] Based on the above analysis, in an exemplary embodiment, this embodiment provides a downhole weight-on-bit and torque measurement method, including the following steps 101 to 108. In which:

[0034] Step 101: Install vibration measurement sensors at both ends of the drill collar.

[0035] Step 102: Establish a relationship between weight on bit and axial relative displacement.

[0036] Step 103: Establish a relationship between torque and relative angular displacement.

[0037] Step 104: During the drilling process, the vibration acceleration at both ends of the drill collar is measured in real time by a vibration measurement sensor; the vibration acceleration includes axial acceleration and tangential acceleration.

[0038] Step 105: Calculate the axial relative displacement between the two end sections of the drill collar based on the axial accelerations at the two ends of the drill collar.

[0039] Step 106: Calculate the relative angular displacement between the cross sections at both ends of the drill collar based on the tangential accelerations at both ends of the drill collar.

[0040] Step 107: Based on the axial relative displacement between the two end sections of the drill collar, the weight on bit of the drill collar is obtained using the relationship between the weight on bit and the axial relative displacement.

[0041] Step 108: Based on the relative angular displacement between the cross sections at both ends of the drill collar, the torque acting on the drill collar is obtained using the relationship between torque and relative angular displacement.

[0042] In implementing steps 101 to 108 above, the vibration measurement sensor is a high-frequency measurement sensor. When measuring downhole vibration data, it is not affected by downhole vibration conditions and the harsh environment of high temperature and high pressure downhole. It can accurately measure vibration acceleration, and then resolve axial relative displacement and relative angular displacement through vibration acceleration. Based on the established relationship between bit weight and axial relative displacement and the relationship between torque and relative angular displacement, the bit weight and torque on the drill collar are calculated, thereby improving the measurement stability and adaptability of downhole bit weight and torque.

[0043] In another exemplary embodiment of the present application, the vibration measurement sensor in step 101 is specifically an acceleration sensor, which has the advantages of small size, small mass, and wide frequency range.

[0044] In another exemplary embodiment of the present application, under the action of the bit pressure P, the length of the elastic drill collar in the axial direction changes from the original L to L+ΔL. Hooke's law of material mechanics in axial tension or compression is:

[0045] σ=Eε (6)

[0046] Where σ is the unidirectional normal stress, E is the elastic modulus of the material, and ε is the linear strain.

[0047]

[0048] Substituting equation (7) into equation (6), the conversion relationship between bit pressure and strain can be obtained as follows:

[0049] P=EAε (9)

[0050] Substituting equation (8) into equation (9), the relationship between bit pressure and axial relative displacement can be obtained as follows:

[0051]

[0052] in:

[0053]

[0054] Where, d m is the outer radius of the drill collar, d i is the inner radius of the drill collar.

[0055] In another exemplary embodiment of the present application, the relationship between torque and relative angular displacement is:

[0056]

[0057] Where: T is the torque applied at both ends of the rotating shaft, G is the shear elastic modulus of the rotating shaft, I p is the polar moment of inertia of the section of the rotating axis, L is the distance between the sections at both ends of the drill collar, is the relative angular displacement.

[0058] Polar moment of inertia of the section about the axis of rotation I p The formula is:

[0059]

[0060] In another exemplary embodiment of the present application, a material analysis of torque measurement is performed: Figure 4 and Figure 5 As shown, a pair of external couples of equal magnitude and opposite direction are applied to the front and rear ends of the shaft, and the rotation angle of the front end of the shaft is The rear end rotation angle of the shaft is Due to the difference in torsion angle The shear strain of the element is generated.

[0061] Take a microelement of length ΔX at any position on the surface. When a torque is applied, the side length AB is twisted to AE, and the twist angle is θ. Let ΔX→dx. The shear strain at radius ρ is obtained:

[0062]

[0063] τ=Gγ (15)

[0064] Where τ is the shear stress, G is the shear elastic modulus, and γ is the shear strain.

[0065] According to Equation (15), shear stress and shear strain are proportional. Therefore, at any cross section of a circular shaft, the shear stress along the radial direction follows the same pattern as the shear strain, increasing linearly along the radial direction. That is, the shear strain reaches its maximum value at the surface of the shaft. Let R be the outer radius and ρ be the distance from the microelement to the cylinder's axis, yielding Equation (16).

[0066] Combining Equations (14) and (15), the total torque T of a cross section is equal to the sum of the moments from the internal forces on each element of the cross section to the center of the circle. The relationship between torque and relative angular displacement is shown in Equation (16).

[0067]

[0068] Where, ∫ A ρ2 dA is the polar moment of inertia of the cross section.

[0069] In another exemplary embodiment of the present application, there is an integral operation relationship between acceleration and displacement, and the displacement signal can be obtained by integrating the measured acceleration signal. Due to the presence of trend terms in time domain integration, the error will gradually amplify during the integration process. In addition, the integral operation itself will produce a constant term that affects the operation result, and polynomial fitting is usually used to eliminate the influence. The frequency domain integration method is used to avoid the error caused by quadratic integration, and has higher stability than time domain integration. Then the above step 105 can be replaced by the following steps 201 to 203:

[0070] Step 201: According to the formula a(t)=Be jωt , perform Fourier transform on the axial acceleration at each end to obtain the Fourier component corresponding to the axial acceleration at each end; where a(t) is the Fourier component at frequency ω, B is the coefficient of axial acceleration at frequency ω, and t is a variable.

[0071] Step 202: Based on the Fourier components corresponding to the axial acceleration at each end, a frequency domain integration algorithm is used to obtain a time domain signal of the displacement at each end.

[0072] Step 203: The difference between the time domain signals of the displacements at both ends is used as the axial relative displacement between the two end sections of the drill collar.

[0073] In another exemplary embodiment of the present application, the acceleration signal is integrated to obtain the velocity signal, and the velocity signal is then integrated to obtain the displacement signal. The formula of the frequency domain integration algorithm in step 202 is:

[0074]

[0075] Where v(t) is the time domain signal of velocity, and s(t) is the time domain signal of displacement.

[0076] In another exemplary embodiment of the present application, the process of calculating the relative angular displacement between the two end sections of the drill collar in step 106 can be replaced by the following steps 301 to 303:

[0077] Step 301: Perform Fourier transform on the tangential acceleration at each end to obtain the Fourier component corresponding to the tangential acceleration at each end.

[0078] Step 302: According to the Fourier components corresponding to the tangential acceleration of each end, a frequency domain integration algorithm is used to obtain a time domain signal of the angular displacement of each end.

[0079] Step 303: The difference between the time domain signals of the angular displacements at both ends is used as the relative angular displacement between the cross sections at both ends of the drill collar.

[0080] Similarly, the axial acceleration data and the tangential acceleration data are processed by Fourier transform, and the frequency domain of the acceleration signal with the same main frequency is multiplied by The frequency domain signal of the displacement is obtained, and then an inverse Fourier transform is performed on the frequency domain signal to obtain the time domain signal of the displacement, i.e., the displacement curve. By comparing the displacements measured by two sensors within a given time t, the relative axial displacement between the two sections caused by axial tension and compression, as well as the relative angular displacement between the two sections caused by relative rotation under torsion, are obtained.

[0081] In another exemplary embodiment of the present application, the vibration measurement sensor at each end of the drill collar is disposed in a vibration measurement sub; the vibration measurement sub is connected to the end of the drill collar via a thread. That is, the method of the present application uses two vibration measurement subs, which are connected to the two ends of the drill collar via a thread, one-to-one. Figure 6 As shown in the figure, the first vibration measurement sub 5 is connected to the upper end of the drill collar 2 via a thread, and the second vibration measurement sub 3 is connected to the lower end of the drill collar 2 via a thread. The first vibration measurement sub 5 collects acceleration information from the upper end of the drill collar 2, while the second vibration measurement sub 3 collects acceleration information from the lower end of the drill collar 2.

[0082] In another exemplary embodiment of the present application, Figure 7 The design structure of the first vibration measurement sub 5 is shown. Figure 8 The design structure of the second vibration measurement sub 3 is shown. The vibration measurement sub comprises a sub body 4, a receiving chamber 7, and a cover plate 5. One end of the sub body 4 is provided with an internal tapered thread, and the other end is provided with an external tapered thread. The sub body 4 is connected to the drill collar 2 via the internal or external tapered threads. The receiving chamber 7 and the cover plate 5 are both mounted on the sub body 4. The vibration measurement sensor is built into the sealed space formed by the receiving chamber 7 and the cover plate 5.

[0083] like Figure 7 As shown, the first vibration measurement sub 5 is connected to one end of the drill collar 2 via an external tapered thread, and the first vibration measurement sub 5 is connected to the drill bit via an internal tapered thread. The second vibration measurement sub 3 is connected to the other end of the drill collar 2 via an internal tapered thread. The cover plate 5 is fixed to the sub body 4 by screws. The acceleration sensor can be a three-axis accelerometer, which performs parameter acquisition, collects acceleration data, and stores it. In addition to the three-axis accelerometer, a built-in battery can also be included in the storage compartment 7. The three-axis accelerometer and battery constitute the sensor integrated unit 6.

[0084] The method of the present application first analyzes the stress deformation model of the drill collar, then analyzes the stress condition of the drill collar by combining the vibration acceleration and other information measured by the built-in sensor of the high-frequency measurement pup joint, and calculates the magnitude of the drilling pressure and torque based on the measured data.

[0085] This application analyzes the relevant force mechanisms of flexible cylinders and, based on the principles of dynamics, analyzes the changes in the relative motion dynamic parameters between any two cross-sections of the cylinder when subjected to drilling pressure and torque. Based on the principles of material mechanics, the application analyzes the relationship between the magnitude of the force deformation of different coaxial cross-sections under drilling pressure and torque and the magnitude of the drilling pressure and torque. At the same time, by installing high-frequency measurement short sections on both sides of the drill collar to measure the tangential torsion parameters of the two different cross-sections of the drill collar, the torque applied to the drill collar at this time is analyzed and calculated. This provides new ideas for simplifying measurement methods, reducing design difficulty, and reducing costs.

[0086] The brief process of this application method is as follows Figure 9 As shown in the figure, first the relative rotation dynamics analysis of the cylinder is carried out, then the downhole vibration data is collected and the acceleration data is preprocessed. Then, the results of the above two steps are combined to calculate the relative displacement through the dynamic data. Finally, based on the principle of material mechanics, the bit pressure and torque are calculated through the relative displacement.

[0087] Based on the same inventive concept, embodiments of the present application also provide a downhole WOB and torque measurement system for implementing the aforementioned downhole WOB and torque measurement method. The solution provided by this system is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more of the following downhole WOB and torque measurement system embodiments can be found in the above-described limitations of the downhole WOB and torque measurement method and are not further elaborated here.

[0088] In an exemplary embodiment, a downhole weight-on-bit and torque measurement system is provided, comprising: a drill tool, a computer, and two vibration measurement sensors. The two vibration measurement sensors are disposed one-to-one at each end of a drill collar of the drill tool; during drilling using the drill tool, the two vibration measurement sensors are used to measure the axial acceleration and tangential acceleration at both ends of the drill collar in real time; the computer is used to establish a relationship between weight-on-bit and axial relative displacement, and a relationship between torque and relative angular displacement, and to receive the axial acceleration and rotational speed at both ends of the drill collar. Based on the axial acceleration at both ends of the drill collar, the computer calculates the axial relative displacement between the two end sections of the drill collar; based on the tangential acceleration at both ends of the drill collar, the computer calculates the relative angular displacement between the two end sections of the drill collar; based on the axial relative displacement between the two end sections of the drill collar, the computer calculates the weight-on-bit on the drill collar using the relationship between weight-on-bit and axial relative displacement; and based on the relative angular displacement between the two end sections of the drill collar, the computer calculates the torque on the drill collar using the relationship between torque and relative angular displacement.

[0089] As an optional implementation, a vibration measurement sensor is provided in a vibration measurement short section. The connection relationship and specific composition of the vibration measurement short section can be found in the above description and will not be repeated here.

[0090] This application proposes a drilling pressure and torque measurement system based on a high-frequency measurement sensor. The high-frequency measurement sensor can accurately measure three-axis acceleration and calculate downhole drilling pressure and torque through three-axis acceleration and dynamic principle analysis.

[0091] The accelerometer used in this application features a small size, low mass, and wide frequency range. Compared to methods using adhesively bonded strain gauges, it eliminates the need for patch placement, simplifying the measurement process. Its layout is simple, eliminating the need for complex patch layout and circuit design. Simply opening a hole to house the vibration measurement sensor reduces structural design complexity and simplifies the amplification and processing of weak current signals. Its structure allows for torque measurement over large areas, which is crucial for guiding drilling operations.

[0092] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A downhole weight on bit and torque measurement method, characterized in that: include: Vibration measurement sensors are respectively set at both ends of the drill collar; Establish the relationship between bit weight and axial relative displacement; The relationship between torque and relative angular displacement is established; the relationship between torque and relative angular displacement is: Where T is the torque applied at both ends of the rotating shaft, G is the shear elastic modulus of the rotating shaft, is the relative angular displacement, ρ is the distance from the infinitesimal element to the axis of the cylinder, dx is the length of the infinitesimal element, and A is the cross-sectional area of ​​the sections at both ends of the drill collar; During the drilling process, the vibration acceleration at both ends of the drill collar is measured in real time by a vibration measurement sensor; the vibration acceleration includes axial acceleration and tangential acceleration; According to the axial acceleration at both ends of the drill collar, the axial relative displacement between the two end sections of the drill collar is calculated; According to the tangential acceleration at both ends of the drill collar, the relative angular displacement between the two end sections of the drill collar is calculated; According to the axial relative displacement between the two end sections of the drill collar, the drilling pressure on the drill collar is obtained by using the relationship between the drilling pressure and the axial relative displacement. According to the relative angular displacement between the two end sections of the drill collar, the torque on the drill collar is obtained by using the relationship between torque and relative angular displacement; According to the axial acceleration at both ends of the drill collar, the axial relative displacement between the two end sections of the drill collar is calculated, specifically including: According to the formula a(t)=Be jωt , perform Fourier transform on the axial acceleration at each end to obtain the Fourier component corresponding to the axial acceleration at each end; where a(t) is the Fourier component at frequency ω, B is the coefficient of axial acceleration at frequency ω, and t is a variable; According to the Fourier components corresponding to the axial acceleration at each end, the frequency domain integration algorithm is used to obtain the time domain signal of the displacement at each end; The difference between the time domain signals of the displacements at both ends is taken as the axial relative displacement between the two end sections of the drill collar.

2. The downhole weight-on-bit and torque measurement method according to claim 1, characterized in that: The relationship between the bit pressure and the axial relative displacement is: Where P is the bit pressure, ΔL is the axial relative displacement, L is the distance between the sections at both ends of the drill collar, ε is the linear strain, and A is the cross-sectional area of ​​the sections at both ends of the drill collar.

3. The downhole weight-on-bit and torque measurement method according to claim 1, characterized in that: The relationship between the torque and the relative angular displacement can also be expressed as: Where T is the torque applied at both ends of the rotating shaft, G is the shear elastic modulus of the rotating shaft, and I p is the polar moment of inertia of the section of the rotating axis, L is the distance between the sections at both ends of the drill collar, is the relative angular displacement.

4. The downhole weight-on-bit and torque measurement method according to claim 1, characterized in that: The formula of the frequency domain integration algorithm is: Where v(t) is the time domain signal of velocity, and s(t) is the time domain signal of displacement.

5. The downhole weight-on-bit and torque measurement method according to claim 1, characterized in that: According to the tangential acceleration at both ends of the drill collar, the relative angular displacement between the cross sections at both ends of the drill collar is calculated, specifically including: Perform Fourier transform on the tangential acceleration at each end to obtain the Fourier component corresponding to the tangential acceleration at each end; According to the Fourier components corresponding to the tangential acceleration at each end, the frequency domain integration algorithm is used to obtain the time domain signal of the angular displacement at each end; The difference in the time domain signals of the angular displacements at both ends is taken as the relative angular displacement between the two end sections of the drill collar.

6. The downhole weight-on-bit and torque measurement method according to claim 1, characterized in that: The vibration measurement sensor at each end of the drill collar is set in a vibration measurement sub; The vibration measuring sub is connected to the end of the drill collar through threads.

7. The downhole weight-on-bit and torque measurement method according to claim 6, characterized in that: The vibration measurement pup joint comprises: a pup joint body, a receiving chamber and a cover plate; One end of the short section body is provided with an internal tapered thread, and the other end of the short section body is provided with an external tapered thread; the short section body is matched and connected with the drill collar through the internal tapered thread or the external tapered thread; The accommodating chamber and the cover plate are both arranged on the short section body; the vibration measurement sensor is built into the sealed space formed by the accommodating chamber and the cover plate.

8. A downhole weight-on-bit and torque measurement system, characterized in that: include: drilling tools, a computer, and two vibration measurement sensors; Two vibration measurement sensors are respectively arranged at both ends of the drill collar of the drilling tool in a one-to-one correspondence; During the drilling process using the drill tool, two vibration measurement sensors are used to measure the axial acceleration and tangential acceleration at both ends of the drill collar in real time; The computer is used to establish a relationship between weight on bit and axial relative displacement and a relationship between torque and relative angular displacement, and receives axial acceleration and rotational speed at both ends of the drill collar, calculates the axial relative displacement between the two end sections of the drill collar based on the axial acceleration at both ends of the drill collar; calculates the relative angular displacement between the two end sections of the drill collar based on the tangential acceleration at both ends of the drill collar; obtains the weight on bit experienced by the drill collar based on the axial relative displacement between the two end sections of the drill collar using the relationship between weight on bit and axial relative displacement; and obtains the torque experienced by the drill collar based on the relative angular displacement between the two end sections of the drill collar using the relationship between torque and relative angular displacement; The relationship between the torque and the relative angular displacement is: Where T is the torque applied at both ends of the rotating shaft, G is the shear elastic modulus of the rotating shaft, is the relative angular displacement, ρ is the distance from the infinitesimal element to the axis of the cylinder, dx is the length of the infinitesimal element, and A is the cross-sectional area of ​​the sections at both ends of the drill collar; According to the axial acceleration at both ends of the drill collar, the axial relative displacement between the two end sections of the drill collar is calculated, specifically including: According to the formula a(t)=Be jωt , perform Fourier transform on the axial acceleration at each end to obtain the Fourier component corresponding to the axial acceleration at each end; where a(t) is the Fourier component at frequency ω, B is the coefficient of axial acceleration at frequency ω, and t is a variable; According to the Fourier components corresponding to the axial acceleration at each end, the frequency domain integration algorithm is used to obtain the time domain signal of the displacement at each end; The difference between the time domain signals of the displacements at both ends is taken as the axial relative displacement between the two end sections of the drill collar.

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