Downhole bit pressure and torque measuring method and system

Abstract

The invention discloses an underground bit pressure and torque measuring method and system, and relates to the field of well drilling measurement. According to the method, vibration measurement sensors are arranged at two ends of a drill collar respectively; in the drilling process, the axial acceleration and the tangential acceleration of the two ends of the drill collar are measured in real time through the vibration measurement sensor; calculating the axial relative displacement between the sections of the two ends of the drill collar according to the axial acceleration of the two ends of the drill collar; calculating the relative angular displacement between the sections of the two ends of the drill collar according to the tangential accelerations of the two ends of the drill collar; according to the axial relative displacement between the sections of the two ends of the drill collar, the bit pressure borne by the drill collar is obtained through the relational expression of the bit pressure and the axial relative displacement; according to the relative angular displacement between the sections of the two ends of the drill collar, the torque borne by the drill collar is obtained through the relation between the torque and the relative angular displacement. The invention provides a novel bit pressure and torque measurement mode, the method is simple to operate and high in anti-interference performance, and the measurement stability and adaptability of the underground bit pressure and torque can be improved.

Description

Technical Field

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

[0002] With the rapid development of the oil and gas industry and the continuous deepening of exploration and development, the amount of surface resources has been declining, and exploration has gradually shifted to deep development. However, the deep geological environment is complex, and problems such as stick-slip vibration, drill jumping, and sudden rotation are prone to occur during drilling, resulting in drill bit tooth collapse and drill tool torsional deformation. This seriously affects the drilling efficiency and drill tool life, resulting in extended drilling cycles and significantly increased costs. Real-time measurement of changes in drilling engineering parameters such as drilling pressure and torque near the drill bit can effectively prevent such accidents and provide technical support for safe and efficient drilling.

[0003] The measurement of drilling pressure and torque at the bottom of the hole can enable drillers to control the drilling process more accurately, reduce drilling risks, and improve the observability and controllability of the drilling well. However, the situation downhole is complicated, and the harsh environment of high temperature and high pressure will interfere with the accuracy of torque and drilling pressure measurement. At present, the measurement of downhole torque is mainly based on the strain measurement principle, using different strain materials to measure drilling pressure and torque, and reducing the measurement error through data processing by pasting different strain gauges, adding pressure sensors, temperature sensors and other methods. However, the vibration conditions of the drill tool in the downhole are severe, and the drill tool is prone to bending and deformation. At the same time, the high temperature downhole will affect the stability of the strain gauge. Summary of the invention

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

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

[0006] In a first aspect, the present application provides a method for measuring downhole drilling pressure and torque, comprising: respectively arranging 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 exerted on the drill collar by using the relationship between drilling pressure and axial relative displacement according to the axial relative displacement between the two end sections of the drill collar; obtaining the torque exerted on the drill collar by using the relationship between torque and relative angular displacement according to 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 the drilling process using the drill tool, the two vibration measurement sensors are used to measure the axial acceleration and tangential acceleration at the two 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 receive the axial acceleration and rotation speed at the two 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 the two 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 the two ends of the drill collar; based on the axial relative displacement between the two end sections of the drill collar, the drilling pressure exerted on the drill collar is obtained by using the relationship between drilling pressure and axial relative displacement; based on the relative angular displacement between the two end sections of the drill collar, the torque exerted on the drill collar is obtained by using the relationship between torque and relative angular displacement.

[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 drilling pressure 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 drilling pressure and axial relative displacement and the relationship between torque and relative angular displacement, the drilling pressure and torque exerted on the drill collar are calculated, thereby improving the measurement stability and adaptability of downhole drilling pressure 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 drawings required for use in the embodiments will be briefly introduced below. 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 paying creative work.

[0011] Figure 1 This is a schematic diagram of changes that occur when a drill collar is subjected to a torsional force in one embodiment of the present application;

[0012] Figure 2 It is a schematic diagram of the changes that will occur in the two cross sections of the drill collar when subjected to a torsional force in one embodiment of the present application;

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

[0014] Figure 4 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 by another embodiment of the present application;

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

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

[0019] Fig. 9 A simplified flowchart of a downhole drilling pressure and torque measurement method provided in one embodiment of the present application.

[0020] Reference numerals:

[0021] A first vibration measuring short section-1, a drill collar-2, a second vibration measuring short section-3, a short section body-4, a cover plate-5, a sensor integrated unit-6, and a containing chamber-7. DETAILED DESCRIPTION

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

[0023] In order to make the above-mentioned objects, 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 torsion. Figure 2 Part (a) and Figure 2 Part (b) shows the changes in the two cross sections of the drill collar when subjected to torsion. 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 mechanisms of flexible cylinders, 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 rotation angle. The dynamic torque measurement model is obtained by subtracting equation (1) from equation (2), as shown in equation (3).

[0028]

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

[0030] (2) The change of the physical quantity of a flexible cylinder when subjected to force is uniform. The change of the physical quantity when axial relative motion occurs between the two cross sections when subjected to force is analyzed.

[0031]

[0032] In the formula, 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 two ends of the flexible cylinder are stretched or compressed, the axial relative positions of the two sections change. When considering the relative displacement, the equation can be transformed into formula (5).

[0033] Based on the above analysis, in an exemplary embodiment, this embodiment provides a method for measuring downhole drilling pressure and torque, including the following steps 101 to 108. Among them:

[0034] Step 101: Vibration measurement sensors are respectively arranged at both ends of the drill collar.

[0035] Step 102: Establish a relationship between bit pressure 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 according to 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 according to the tangential acceleration at both ends of the drill collar.

[0040] Step 107: 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.

[0041] Step 108: According to the relative angular displacement between the cross sections at both ends of the drill collar, the torque applied to the drill collar is obtained by using the relationship between the torque and the relative angular displacement.

[0042] In implementing the above steps 101 to 108, 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, and can accurately measure vibration acceleration, and then solve the axial relative displacement and relative angular displacement through vibration acceleration, and based on the established relationship between drilling pressure and axial relative displacement and the relationship between torque and relative angular displacement, the drilling pressure and torque on the drill collar are calculated, thereby improving the measurement stability and adaptability of downhole drilling pressure and torque.

[0043] In another exemplary embodiment of the present application, the vibration measurement sensor in the above 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 drilling pressure P, the length of the elastic drill collar in the axial direction changes from the original L to L+△L. 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 drilling 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 of the rotating axis I p The formula is:

[0059]

[0060] In another exemplary embodiment of the present application, the 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. After applying torque, 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 formula (15), shear stress and shear strain have a proportional relationship. Therefore, on any cross section of the circular axis, the change law of radial shear stress is consistent with that of shear strain, and both increase linearly along the radial direction, that is, the shear strain reaches the maximum value on the surface of the circular axis. Let R be the outer radius and ρ be the distance from the microelement to the axis of the cylinder, and we can get formula (16).

[0066] Combining equations (14) and (15), the total torque T of the cross section is equal to the sum of the moments from the internal force on each microelement 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] In the formula, ∫ 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 existence of trend terms in time domain integration, the error will gradually increase during the integration process. In addition, the integral operation itself will produce constant terms that affect the operation results, 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, which has higher stability than the 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: According to the Fourier component corresponding to the axial acceleration of each end, a frequency domain integration algorithm is used to obtain a time domain signal of the displacement of 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 the above 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 component 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 the frequency domain signal of the displacement is inversely transformed by Fourier to obtain the time domain signal of the displacement, that is, the displacement curve. The displacement comparison is measured by two sensors within a given time t to obtain the axial relative displacement caused by axial tension and compression between the two sections and the relative angular displacement caused by relative rotation between the two sections under the action of torsion.

[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 through a thread. That is, the method of the present application uses two vibration measurement subs, and the two vibration measurement subs are connected to the two ends of the drill collar one by one through threads, such as Figure 6 As shown. The first vibration measuring sub 5 is connected to the upper end of the drill collar 2 through a thread, and the second vibration measuring sub 3 is connected to the lower end of the drill collar 2 through a thread. The first vibration measuring sub 5 collects acceleration information of the upper end of the drill collar 2, and the second vibration measuring sub 3 collects acceleration information of 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 short section 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 conical thread, and the other end of the sub body 4 is provided with an external conical thread; the sub body 4 is matched and connected with the drill collar 2 through the internal conical thread or the external conical thread; the receiving chamber 7 and the cover plate 5 are both provided on the sub body 4; and the vibration measurement sensor is built in the sealed space formed by the receiving chamber 7 and the cover plate 5.

[0083] like Figure 7 As shown, the first vibration measuring short section 5 is connected to one end of the drill collar 2 through an external tapered thread, and the first vibration measuring short section 5 is connected to the drill bit through an internal tapered thread. The second vibration measuring short section 3 is connected to the other end of the drill collar 2 through an internal tapered thread. The cover plate 5 is fixed to the short section 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 battery can also be built-in in the accommodation chamber 7. The three-axis accelerometer and the battery constitute a 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 in combination with information such as vibration acceleration measured by a sensor built into a high-frequency measurement sub, and calculates the drilling pressure and torque in combination with the measured data.

[0085] This application analyzes the relevant mechanism of the force on the flexible cylinder, and based on the principle 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 principle of material mechanics, analyzes the relationship between the magnitude of the force deformation of different coaxial sections under the action of drilling pressure and torque and the magnitude of 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 two different cross-sections of the drill collar, the torque to which the drill collar is subjected at this time is analyzed and calculated. This provides new ideas for simplifying the measurement method, reducing the difficulty of design, and reducing costs.

[0086] The brief process of this application method is as follows Fig. 9 As shown, firstly, the relative rotation dynamics analysis of the cylinder is carried out, then the downhole vibration data is collected, the acceleration data is preprocessed, and 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 drilling pressure and torque are calculated through the relative displacement.

[0087] Based on the same inventive concept, the embodiment of the present application also provides a downhole drilling pressure and torque measurement system for implementing the downhole drilling pressure and torque measurement method involved above. The implementation scheme for solving the problem provided by the system is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more downhole drilling pressure and torque measurement system embodiments provided below can refer to the above limitations on the downhole drilling pressure and torque measurement method, and will not be repeated here.

[0088] In an exemplary embodiment, a downhole drilling pressure and torque measurement system is provided, including: a drilling 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 drilling tool in a one-to-one correspondence; during the drilling process using the drilling tool, the two vibration measurement sensors are used to measure the axial acceleration and tangential acceleration of the two 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 receive the axial acceleration and rotation speed at the two 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 the two 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 the two ends of the drill collar; 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 drilling pressure and 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.

[0089] As an optional implementation, a vibration measurement sensor is disposed 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] The present application proposes a drilling pressure and torque measurement system based on a high-frequency measurement sensor, which can accurately measure three-axis acceleration, and calculate downhole drilling pressure and torque through three-axis acceleration and dynamic principle analysis.

[0091] The acceleration sensor used in this application is small in size, small in mass and has a wide frequency range. Compared with the method of sticking strain gauges, it does not require patches, which simplifies the measurement process. The layout is simple and does not require complex layout and circuit design. It only needs to open a hole to place the vibration measurement sensor, which reduces the difficulty of structural design. At the same time, it simplifies the amplification and processing process of weak current signals. Structurally, it can be used for torque measurement in large parts, which is of great significance for guiding the progress of drilling work.

[0092] The technical features of the above embodiments may 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 article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will 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 drilling pressure and torque measurement method, characterized in that: include: Vibration measurement sensors are respectively arranged at both ends of the drill collar; Establish the relationship between bit pressure and axial relative displacement; Establish the relationship between torque and relative angular displacement; 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 cross sections at both ends 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 cross sections at both ends of the drill collar, the torque acting on the drill collar is obtained by using the relationship between the torque and the relative angular displacement.

2. The downhole drilling pressure 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 drilling pressure and torque measurement method according to claim 1, characterized in that: 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, 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 drilling pressure and torque measurement method according to claim 1, characterized in that: 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 microelement to the axis of the cylinder, dx is the length of the microelement, and A is the cross-sectional area of ​​the sections at both ends of the drill collar.

5. The downhole drilling pressure and torque measurement method according to claim 1, characterized in that: 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, 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.

6. The downhole drilling pressure and torque measurement method according to claim 5, 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.

7. The downhole drilling pressure 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, 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 of 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.

8. The downhole drilling pressure and torque measurement method according to claim 1, characterized in that: The vibration measurement sensor at each end of the drill collar is arranged in a vibration measurement sub; The vibration measuring nipple is connected to the end of the drill collar through threads.

9. The downhole drilling pressure and torque measurement method according to claim 8, characterized in that: The vibration measurement pup joint comprises: a pup joint body, a containing 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 in the sealed space formed by the accommodating chamber and the cover plate.

10. A downhole drilling pressure and torque measurement system, characterized in that: include: drilling tools, computers and two vibration measurement sensors; Two vibration measurement sensors are respectively arranged at two ends of the drill collar of the drilling tool in a one-to-one correspondence; During the drilling process using the drill bit, 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 receives the axial acceleration and rotation speed at both ends of the drill collar, and calculates 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; calculates 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; obtains the drilling pressure on the drill collar based on the axial relative displacement between the two end sections of the drill collar and the relationship between drilling pressure and axial relative displacement; obtains the torque on the drill collar based on the relative angular displacement between the two end sections of the drill collar and the relationship between torque and relative angular displacement.

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