CN111577268A - A method for judging rock lithology using vibration parameters of drilling tools - Google Patents

Abstract

The invention discloses a method for judging rock lithology by using drilling tool vibration parameters, which comprises the following steps: extracting vibration data of the drilling tool; analyzing rock lithology according to the acceleration root mean square, the stress-strain relation and the mechanical specific energy by using the vibration data; wherein the mechanical specific energy is the minimum energy required to remove a unit volume of rock. The method adopted by the invention has simpler operation steps and is easy to use. The method for analyzing the lithology of the rock mass by using the vibration data is an innovative method. The method has good operability and economic value in well logging, not only saves complex and tedious operation processes in well logging, but also greatly saves the construction period, and has great benefit for accelerating the progress of engineering construction.

Description

A method for judging rock lithology using vibration parameters of drilling tools

technical field

The invention relates to the technical field of rock mass measurement, in particular to a method for judging rock lithology by using vibration parameters of drilling tools.

Background technique

With the development of drilling technology today, logging technology has become an indispensable part of drilling operations. Well logging technology is an engineering technical measure to test reservoirs by applying geophysical methods. Through various applications of sound, light, electricity, magnetism, radioactivity, etc., the physical parameters of the formation are reflected, various logging data are obtained, and the data are further interpreted and analyzed, so as to be applied in drilling engineering.

In drilling engineering, the measurement of drilling surrounding rock lithology is of great significance. The strength of rock lithology is directly related to the progress of drilling engineering. When the lithology of the surrounding rock of the drilling is successfully measured, the technicians can clearly analyze the overall lithologic distribution of the surrounding rock and the variation of the lithology with the drilling depth. Due to the continuity of the stratum, when the lithology of the surrounding rock of a drilling is clear, the technical personnel can design the drilling and drilling implementation plan according to the law of the change of the stratum lithology. During the drilling process, as the drilling depth of the drilling tool increases, the types of rocks also change. Due to the different strengths of different rock masses, in order to meet the drilling needs, the drill bits used for drilling also need to be continuously adjusted. Therefore, the types of drill bits required in the drilling process can be reasonably designed and adjusted according to the lithology of the formation, so as to improve the drilling efficiency and reduce the occurrence of drilling failures. At the same time, in oil drilling, when the staff correctly grasps the lithology distribution of the formation, the hydraulic fracturing area can be effectively designed to provide oil and gas production. Because the selection of hydraulic fracturing area is extremely important, brittle rock mass is easier to fracturing than plastic rock mass, and can generate larger fractures.

Today's logging technology can measure rock lithology mainly include acoustic logging technology, imaging logging technology, resistivity logging technology and radioactive logging technology. Sonic logging mainly applies the characteristics of the borehole and then emits acoustic waves. The condition of the wellbore soil path; Imaging logging is a very comprehensive technology. When using this technology, it will be applied to a large number of electronic equipment, and at the same time, the supporting computer should be used to analyze the data according to the data analyzer. High-quality maps can be obtained by using imaging technology, and the information content is very comprehensive; the working principle of resistivity logging technology is mainly to use logging tools to launch current into the formation, and then calculate the resistance generated by the current in the formation. The radioactive logging technology is to study and analyze the properties of the nuclear material in the interstitial fluid between the formation rocks.

However, the judgment of lithology by these techniques is based on indirect information and does not involve the interaction between the drill bit and the formation. At the same time, these methods have complicated operation steps, many restrictive factors, and require professional instruments to be used together, which are expensive to use. The invention analyzes the rock lithology according to the vibration data measured near the drill bit, makes full use of the data generated by the measurement while drilling, and fills the vacancy that the measurement while drilling cannot measure the rock lithology. Using this method to measure rock lithology, the measurement results are more accurate, and the operation is relatively simple, which can save more time and economic cost, thereby improving engineering efficiency.

Therefore, the present invention is proposed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a simple and easy-to-use method for judging rock lithology by using vibration parameters of drilling tools.

In order to solve the above problems, an embodiment of the present invention provides a method for judging rock lithology by using vibration parameters of drilling tools, including the following steps:

Extract the vibration data of drilling tools;

Using the vibration data, the rock lithology is analyzed according to acceleration root mean square, stress-strain relationship and mechanical specific energy; wherein the mechanical specific energy is the minimum energy required to remove a unit volume of rock.

Further, analyzing the rock lithology according to the acceleration root mean square includes: using the axial acceleration of the drilling tool to calculate the drilling tool acceleration root mean square, and analyzing the lithology according to the acceleration root mean square.

Further, calculating the root mean square of the acceleration of the drilling tool by using the axial acceleration of the drilling tool, and analyzing the lithology according to the root mean square of the acceleration includes:

(1) Obtain the three-axis accelerometer data Ax, Ay, Az stored in the measurement short section;

(2) Filter the three-axis acceleration data;

(3) Calculate the root mean square value RMS of the axial acceleration Az per unit time;

(4) Judging the change of rock mass lithology during drilling according to the change of RMS value; when the RMS value increases, it indicates that the strength of the rock mass drilled by the drilling tool decreases; when the RMS value decreases, it indicates that the rock mass drilled by the drilling tool has a lower strength. strength increases.

Further, the analysis of rock lithology according to the stress-strain relationship includes:

(1) Extract the data in the near-drilling recorder, complete the data transformation and filter processing to remove clutter, and obtain the data of axial acceleration and axial angular velocity;

(2) When the drilling tool is drilling perpendicular to the rock formation, the maximum principal stress of the drilling tool is the torsion force δ ₁ , and the minimum principal stress is the axial stress δ ₃ ; within the unit time T, the drilling displacement of the drilling tool is ε ₃ ; this The root mean square value of the angular acceleration is regarded as the torque δ ₁ ; the root mean square value of the axial acceleration is regarded as the axial stress δ ₃ ; the axial displacement per unit time is ε ₃ , which is equivalent to the zero frequency of the axial displacement spectrum value;

(3) When the drilling direction of the drilling tool is parallel to the rock formation, the maximum principal stress of the drilling tool is the axial stress δ ₁ , and the minimum principal stress is the torsional force δ ₃ ; in the unit time T, the drilling displacement of the drilling tool is ε ₃ ; At this time, the root mean square value of the axial acceleration is regarded as the axial stress δ ₁ ; the root mean square value of the angular acceleration is regarded as the torsion force δ ₃ ; the axial displacement per unit time is ε ₃ , which is equivalent to zero of the rotational displacement spectrum frequency value;

According to the above data, the stress-strain relationship is obtained.

Further, the mechanical specific energy includes two parts, one part is the energy E ₁ in the axial direction of the drill bit, and the other part is the torsional energy E ₂ perpendicular to the axial direction of the drill bit.

Further, the axial energy E ₁ of the drill bit is calculated by multiplying the axial force of the drill bit by the axial displacement of the drill bit; the torsional energy E ₂ is calculated by multiplying the torsional displacement by the torsional force.

Further, the analysis of rock lithology according to mechanical specific energy includes:

(1) Select the axial acceleration in the data that has been transformed and filtered, and then use the axial acceleration to calculate the root mean square value of the axial acceleration;

(2) At this time, the axial displacement per unit time is equivalent to the zero frequency value of the axial displacement spectrum;

(3) According to steps (1) and (2), the energy E ₁ acting axially on the rock mass per unit time is calculated.

(4) Calculate the angular acceleration according to the data recorded by the gyroscope, and use the angular acceleration to calculate the rotational displacement of the drilling tool per unit time;

(5) Calculate the root mean square value of the angular acceleration based on the already calculated angular acceleration.

(6) Calculate the rotational energy E ₂ consumed by the drilling tool according to steps (4) and (5).

(7) Calculate the specific energy consumed according to the calculation results of steps (3) and (6), and judge the strength of the lithology according to the specific energy required by different rock masses; when the specific energy is drilled continuously with the drill bit , the larger the specific energy required to destroy the rock mass, the stronger the rock strength is.

Further, the results calculated by the three analysis methods of acceleration root mean square, stress-strain relationship and mechanical specific energy are compared, and the correlation analysis is used to judge the interdependence of the results of the three analysis methods.

Compared with the prior art, the present invention has the following beneficial effects: the method adopted in the present invention has relatively simple operation steps and is easy to use. The use of vibration data to analyze rock mass lithology is an innovative approach. This method has good operability in logging and has good economic value. It not only saves the complicated and tedious operation process in well logging, but also greatly saves the construction period, which is of great benefit to the acceleration of the progress of the engineering construction.

In modern engineering drilling, vibration measurement is widely used to analyze the vibration of drilling tools and the attitude of drilling tools. The data used in the invention are generally consistent with the types of data for judging the vibration of the drilling tool and the attitude of the drilling tool. Therefore, using the vibration data of the drilling tool to analyze and judge the lithology of the rock mass drilled by the drilling tool not only makes full use of the vibration data, but also reduces the related operations in the logging work, saving a lot of time and economic costs.

Description of drawings

Fig. 1 is the overall flow chart of the method for judging rock lithology by using drilling tool vibration parameters provided by an embodiment of the present invention;

Fig. 2 is the concrete flow chart of the method for judging rock lithology by using drilling tool vibration parameters provided by the embodiment of the present invention;

Fig. 3 is the data processing flow chart of the stress-strain relationship;

Figure 4 is a schematic diagram of the stress state when the symmetry axis of the rock formation is parallel to the drilling;

Figure 5 is a schematic diagram of the stress state when the symmetry axis of the rock formation is perpendicular to the drilling.

Detailed ways

The principles and spirit of the present invention will now be described with reference to several exemplary embodiments illustrated in the accompanying drawings. It should be understood that these embodiments are described only to enable those skilled in the art to better understand and implement the present invention, but not to limit the scope of the present invention in any way.

Definitions of acronyms and key terms

Short joint: a commonly used accessory in industrial piping

Sealed compartment: A compartment that is isolated from the external environment and can accommodate a certain volume of equipment

Cover: A lid, hood or top used to close or cover the section of a container or structure.

The embodiment of the present invention provides a near-bit vibration data measured by an accelerometer and a gyroscope, and uses the stress-strain relationship and the specific energy method to analyze the data recorded by the recorder, so as to determine the basic rock of the drilling tool drilling into the rock mass. Methods of lithology and lithology changes.

In order to invent such a method, the inventor has devoted a lot of creative work in researching the technical principle. Although the research process of the principle is not equivalent to the technical solution of the embodiment of the present invention, it is also an important factor to reflect the inventiveness of the present invention. part.

The drilling process of the drilling tool is the process of breaking the rock mass by the drill bit, and the vibration of the drilling tool is the result of the interaction between the drill bit and the rock mass. When the drill bit interacts with the rock mass, the drill bit exerts a force on the rock mass, and the rock mass is deformed when the force is applied. When the force exceeds the strength limit of the rock mass, the rock mass will rupture. When the drill bit encounters different types of rock mass during the drilling process, the lithology of the rock will also change with the change of the rock. Due to the different lithology of the rock, the vibration generated by the drilling tool will also change when it is broken. During the drilling process, the drill bit interacts with the rock mass. Since the lithology of the rock mass changes continuously with the drilling depth of the drill bit, the drilling state of the drilling tool during the drilling process is different. The vibration generated near the drill bit Data is also different. The vibration data generated by the interaction between the drill bit and the rock mass can more directly reflect the drilling situation of the drilling tool. Therefore, this method uses the vibration data of the drilling tool recorded by the recorder under different drilling conditions to analyze the lithology of the rock body drilled by the drill bit and its changing trend. The operation steps are shown in flowchart 1.

The method utilizes the data about drilling tool vibration recorded by the recorder to complete the analysis of rock mass lithology and lithology changes. The data is processed and analyzed from three aspects to complete the analysis of rock mass lithology: (1) Use acceleration root mean square to judge rock lithology changes. (2) Judging the lithology and its changing trend according to the stress-strain relationship; (3) Judging the change of lithology according to the mechanical specific energy method;

(1) Use the acceleration root mean square to judge the change of rock lithology. When the drilling tool is drilling normally, if the lithology of the rock to be drilled is single and other conditions remain unchanged, the drilling speed of the drill bit remains stable. At this time, the drilling speed fluctuation is small, that is, the root mean square change value of the axial acceleration per unit time is small. When the drill bit reaches the boundary of the rock formation, the lithology of the rock mass will change, and the strength of the rock mass on both sides of the boundary is relatively different. When the lithology of the rock mass changes, after the drill bit applies stress to the rock mass, the vibration of the drill bit due to the interaction between the rock mass and the drill bit will change. At the same time, when a rock crack is encountered during the drilling process, the root mean square value of the drilling acceleration will also change. However, the change time is short and it will return to the original stable state. Therefore, this method can also identify rock cracks.

(2) Judging the lithology and its changing trend according to the stress-strain relationship. The rock mass drilled by the drilling tool can be regarded as a transversely isotropic medium (TI), and the vibration of the drilling tool is the result of the interaction between the drill bit and the rock mass. When the drill bit applies force to the rock mass, the rock mass deforms when the force is applied. When the force exceeds the strength limit of the rock mass, the rock mass will break, and the drill bit will drill accordingly. According to this principle, the elastic modulus E and Poisson's ratio Pr of the rock mass can be calculated by using the stress-strain relationship.

(3) Judging the change of lithology according to the specific energy method. Specific energy refers to the minimum energy required to remove a unit volume of rock mass during drilling. The drilling speed and the cutting depth of the drill bit can be effectively learned through the mechanical specific energy, so the change trend of the rock mass strength can be learned through the change of this value. This method provides a measure of the strength of a rock mass, that is, the minimum amount of energy required to remove the rock mass. Because the strength of different rock masses is different, the energy required to remove the same amount of rock mass is different. When the energy required to remove the same volume of rock mass changes, it indicates that the lithology of the rock has changed. Therefore, it is feasible to judge the strength of the rock mass by the amount of energy required by the drilled rock mass.

Therefore, this method can analyze lithology according to the following steps, as shown in flow chart 2. First, the vibration data is extracted from the relevant recorder, and the data is preliminarily processed by the self-help software to complete the data transformation; after the data is processed by the edited software, the data is subjected to high-frequency filtering processing, so as to complete the data. Basic processing. Then use different data to analyze the rock lithology according to three methods, and analyze and compare according to the three analysis results, and finally get the final result.

Below, a method for judging rock lithology by using vibration parameters of drilling tools provided in the embodiment of the present invention is introduced in detail, including the following steps:

Extract the vibration data of drilling tools;

Using the vibration data, the rock lithology is analyzed according to acceleration root mean square, stress-strain relationship and mechanical specific energy; wherein the mechanical specific energy is the minimum energy required to remove a unit volume of rock. Below, the detailed steps of the above three methods are introduced.

1. Use acceleration root mean square to analyze lithology

(1) Acquire the three-axis accelerometer data Ax, Ay, Az stored in the measurement subsection.

(2) Perform basic filtering processing on the three-axis acceleration data to reduce the measurement error.

(3) Calculate the root mean square value of the axial acceleration Az per unit time, first square the acceleration, then take the squared average (time is T, the number of samples is N), and finally the calculation result is squared to obtain Take the root mean square RMS of the acceleration.

(4) Judging the change of rock mass lithology during drilling process according to the change of RMS value. When the RMS value increases, it indicates that the strength of the rock mass drilled by the drilling tool decreases, and the drilling tool drills from the area with higher rock mass strength to the area with lower rock mass strength; when the RMS value decreases, it indicates that the rock mass drilled by the drilling tool The strength of the rock mass increases, and the drilling tool drills from the area with lower rock mass strength to the area with higher rock mass strength.

Root mean square value RMS calculation formula:

或

or

axial acceleration is the axial acceleration.

According to this method, the change of the acceleration root mean square value can be judged, so as to deduce the vibration of the drilling tool during the drilling process. When the RMS changes, it indicates that the drill bit encounters fractures or lithological boundaries during the drilling process.

2. Analyze lithology according to stress-strain relationship

The process of drilling and drilling is the process of rock mass destruction. When the rock mass is damaged by force, the drilling tool has been drilled. Under the normal working conditions of the drilling tool, the vibration of the drilling tool is mainly the result of the interaction between the rock mass and the drilling tool. In this method, the drilled rock mass is regarded as a transverse homogeneous medium (TI), and the lithology of the rock mass is analyzed by applying the stress-strain relationship under this condition. The specific steps are shown in flowchart 3;

(1) Extract the data from the recorder installed near the drill, and use the relevant software to complete the data transformation and filter to remove the clutter to reduce the interference of the clutter, thereby improving the accuracy of the analysis results. The data ω of the axial acceleration A _Z and the axial angular velocity after the transformation and filtering processing is performed.

(2) According to the analysis, the force of the drilling tool is different under different drilling conditions. When the drilling direction of the drilling tool is perpendicular to the rock formation, the bit (rock mass) is mainly affected by torsion δ ₁ and axial force δ ₃ ; when the drilling direction of the drilling tool is parallel to the rock formation, the bit (rock mass) is mainly affected by Axial force δ ₁ and torsion force δ ₃ act; as shown in Figures 4 and 5.

Stress-strain calculation formula:

(3) When the drilling tool is drilling perpendicular to the rock formation, the maximum principal stress on the drilling tool (rock mass) is torsion force δ ₁ , and the minimum principal stress is axial force δ ₃ . In unit time T, the drilling displacement of the drilling tool is ε ₃ .

(4) The maximum principal stress is the torsion force δ ₁ , and the root mean square value of the angular acceleration can be regarded as the torsion force at this time. First, the angular acceleration α is calculated using the angular velocity data ω, and then the RMS _{angular acceleration} is calculated using the RMS formula. (This torque δ ₁ can be measured with a torque sensor)

(5) The minimum principal stress is the axial stress δ ₃ , and the axial acceleration RMS value can be regarded as the axial stress at this time.

(6) The axial displacement per unit time is ε ₃ , at this time the axial displacement is equal to the ZFL (zero frequency value) of the axial displacement spectrum. This method utilizes the processed axial acceleration, first performs fast Fourier transform on the axial acceleration, and then integrates the transformed result twice, and the result obtained after double integration is the ZFL of the axial displacement spectrum ( zero frequency value).

(7) When the drilling direction of the drilling tool is parallel to the rock formation, the maximum principal stress on the drill bit (rock mass) is axial force δ ₁ , and the minimum principal stress is torsion force δ ₃ . In unit time T, the drilling displacement of the drilling tool is ε ₃ .

(8) The maximum principal stress is the axial force δ ₁ , and the root mean square value of the acceleration can be regarded as the axial force. The RMS _{axial acceleration} is calculated using the RMS formula.

(9) The minimum principal stress is the torsion force δ ₃ , and the root mean square value of the angular acceleration can be regarded as the torsion force at this time. First, the angular acceleration α is calculated using the angular velocity data ω, and then the RMS _{angular acceleration} is calculated using the RMS formula. (This torque δ ₁ can be measured with a torque sensor)

(10) The rotational displacement per unit time is ε ₃ , and the rotational displacement is equivalent to the ZFL (zero frequency value) of the rotational displacement spectrum at this time. This method utilizes the processed angular velocity, first performs fast Fourier transform on the rotational angular velocity, and then integrates the transformed result, which is the ZFL (zero frequency value) of the rotational displacement spectrum.

3. Analysis of lithology according to mechanical specific energy method

In drilling operations, specific energy refers to the minimum effort required to remove a unit volume of rock. The specific energy method can effectively understand the drilling speed and the cutting depth of the drill bit, so the change trend of the rock mass strength can be understood through the change of this value. The larger the energy required per unit volume of rock mass, the harder the rock mass. Therefore, according to this principle, the present invention provides a method for measuring the strength of a rock mass: the lithology of the rock is judged by measuring the minimum energy required to remove the rock mass.

According to the principles of mechanics, the energy required to remove a unit volume of rock can be multiplied by the displacement of the drill bit by the force on the drill bit. The specific energy can be divided into two parts: one part is the energy E ₁ in the axial direction of the drill bit, and the other part is the energy E ₂ perpendicular to the axial direction of the drill bit (torsional energy).

The specific energy calculation formula is:

MSE=E ₁ +E ₂

E ₁ =RMS _{axial acceleration} ·ZEL _{axial displacement} ;

where ω is the axial angular velocity and f is the rotational frequency. The axial portion E ₁ can be calculated by multiplying the axial force of the drill bit by the axial displacement of the drill bit; the torsional energy E ₂ can be obtained by multiplying the torsional displacement by the torsional force. The specific operation steps are as follows:

(1) Select the axial acceleration A- _axis from the data that has been transformed and filtered, and then use the axial acceleration to calculate the root mean square value of the axial acceleration.

(2) At this time, the axial displacement per unit time is equivalent to the ZFL (zero frequency value) of the axial displacement spectrum. This method utilizes the processed axial acceleration, first performs fast Fourier transform on the axial acceleration, and then integrates the transformed result twice, and the result obtained after double integration is the ZFL of the axial displacement spectrum ( zero frequency value).

(3) According to steps 1 and 2, the energy E ₁ acting axially on the rock mass per unit time can be calculated.

(4) According to the data recorded by the gyroscope, calculate the angular velocity change - angular acceleration α in adjacent time periods, and use the angular acceleration to calculate the rotational displacement of the drilling tool per unit time.

(5) Calculate the root mean square value RMS of the angular acceleration based on the already calculated angular acceleration.

(6) According to steps 4 and 5, the rotational energy E ₂ consumed by the drilling tool can be calculated.

(7) Calculate the consumed specific energy according to the calculation results of steps 3 and 6, and judge the strength of lithology according to the required specific energy of different rock masses. When the specific energy is continuously drilled with the drill bit, the larger the specific energy required to destroy the rock mass, the stronger the rock strength is.

4. Comprehensive analysis of rock lithology

In the present invention, all the above three methods can complete the analysis of rock lithology. However, considering the existence of noise interference and calculation errors, the three methods are integrated to increase the analysis accuracy. This method compares the calculated results of the three analysis methods, and uses correlation analysis to judge the interdependence of the results of the three analysis methods. Since the three methods are all direct analysis of rock lithology, the results of the three methods have good similarity.

The technical scheme proposed by the present invention is aimed at analyzing lithology. The scheme adopts innovative measurement methods, effectively combines vibration data and lithology analysis, and uses stress-strain relationship, mechanical specific energy and other methods to analyze and judge lithology. The purpose of judging rock mass lithology by using vibration data mentioned in the present invention can only be achieved by this solution. Other technical solutions that are not significantly different from the innovative points of this solution on the basis of this solution can be regarded as within the scope of this solution.

Specific examples are used herein to describe the inventive concept in detail, and the descriptions of the above embodiments are only used to help understand the core idea of the present invention. It should be pointed out that for those skilled in the art, any obvious modifications, equivalent replacements or other improvements made without departing from the inventive concept should be included within the protection scope of the present invention.

Claims (8)

1. a method utilizing drilling tool vibration parameter to judge rock lithology, is characterized in that, comprises the steps: Extract the vibration data of drilling tools; Using the vibration data, the rock lithology is analyzed according to acceleration root mean square, stress-strain relationship and mechanical specific energy; wherein the mechanical specific energy is the minimum energy required to remove a unit volume of rock. 2. The method according to claim 1, wherein analyzing the rock lithology according to the acceleration root mean square comprises: using the axial acceleration of the drilling tool to calculate the drilling tool acceleration root mean square, according to the acceleration root mean square. Root mean square analysis of lithology. 3. The method according to claim 2, wherein, calculating the root mean square of the acceleration of the drilling tool by using the axial acceleration of the drilling tool, and analyzing the lithology according to the root mean square of the acceleration comprises: (1) Obtain the three-axis accelerometer data Ax, Ay, Az stored in the measurement short section; (2) Filter the three-axis acceleration data; (3) Calculate the root mean square value RMS of the axial acceleration Az per unit time; (4) Judging the change of rock mass lithology during drilling according to the change of RMS value; when the RMS value increases, it indicates that the strength of the rock mass drilled by the drilling tool decreases; when the RMS value decreases, it indicates that the rock mass drilled by the drilling tool has a lower strength. strength increases. 4. The method according to claim 1, wherein the analysis of rock lithology according to the stress-strain relationship comprises: (1) Extract the data in the near-drilling recorder, complete the data transformation and filter processing to remove clutter, and obtain the data of axial acceleration and axial angular velocity; (2) When the drilling tool is drilling perpendicular to the rock formation, the maximum principal stress of the drilling tool is the torsion force δ ₁ , and the minimum principal stress is the axial stress δ ₃ ; within the unit time T, the drilling displacement of the drilling tool is ε ₃ ; this The root mean square value of the angular acceleration is regarded as the torque δ ₁ ; the root mean square value of the axial acceleration is regarded as the axial stress δ ₃ ; the axial displacement per unit time is ε ₃ , which is equivalent to the zero frequency of the axial displacement spectrum value; (3) When the drilling direction of the drilling tool is parallel to the rock formation, the maximum principal stress of the drilling tool is the axial stress δ ₁ , and the minimum principal stress is the torsional force δ ₃ ; in the unit time T, the drilling displacement of the drilling tool is ε ₃ ; At this time, the root mean square value of the axial acceleration is regarded as the axial stress δ ₁ ; the root mean square value of the angular acceleration is regarded as the torsion force δ ₃ ; the axial displacement per unit time is ε ₃ , which is equivalent to zero of the rotational displacement spectrum frequency value; According to the above data, the stress-strain relationship is obtained. 5 . The method according to claim 1 , wherein the mechanical specific energy includes two parts, one part is the energy E ₁ in the axial direction of the drill bit, and the other part is the torsional energy E ₂ perpendicular to the axial direction of the drill bit. 6 . The method according to claim 5 , wherein the axial energy E ₁ of the drill bit is calculated by multiplying the axial force of the drill bit by the axial displacement of the drill bit; the torsional energy E ₂ is calculated by multiplying the torsional displacement by the torsional force. 7. The method according to claim 6, wherein the analysis of rock lithology according to mechanical specific energy comprises: (1) Select the axial acceleration in the data that has been transformed and filtered, and then use the axial acceleration to calculate the root mean square value of the axial acceleration; (2) At this time, the axial displacement per unit time is equivalent to the zero frequency value of the axial displacement spectrum; (3) According to steps (1) and (2), the energy E ₁ acting axially on the rock mass per unit time is calculated. (4) Calculate the angular acceleration according to the data recorded by the gyroscope, and use the angular acceleration to calculate the rotational displacement of the drilling tool per unit time; (5) Calculate the root mean square value of the angular acceleration based on the already calculated angular acceleration. (6) Calculate the rotational energy E ₂ consumed by the drilling tool according to steps (4) and (5). (7) Calculate the specific energy consumed according to the calculation results of steps (3) and (6), and judge the strength of the lithology according to the specific energy required by different rock masses; when the specific energy is drilled continuously with the drill bit , the larger the specific energy required to destroy the rock mass, the stronger the rock strength is. 8. The method according to claim 1, wherein the calculated results of the three analytical methods of acceleration root mean square, stress-strain relationship and mechanical specific energy are used for comparison, and correlation analysis is used to judge the three analytical methods interdependence of results.

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