Method for continuously testing mechanical parameters of rock in situ in well

Abstract

The invention discloses a method for in-situ continuous testing of rock mechanical parameters in a well, and relates to the technical field of rock mechanical testing. The invention discloses a method for continuously testing mechanical parameters of rocks in situ in a well. The method comprises the following specific steps of wellbore preparation, equipment preparation, equipment entering the well, pre-testing, testing operation, data processing and analysis and result output. According to the invention, controllable continuous micro-etching is carried out on well wall rocks by using an underground device, in-situ dynamic testing of rock mechanical parameters is realized, and the limitation of discrete measurement is broken through; automatically optimizing control head motion parameters and repairing noise data; a temperature / pressure compensation module is arranged, the method adapts to the complex underground environment with the temperature larger than or equal to 150 DEG C and the pressure larger than or equal to 60 MPa, in-situ rapid measurement of rock mechanical parameters is achieved in combination with a mechanical model, well wall rocks are directly tested, the mechanical parameters of the rocks are obtained, and the problems that a traditional method is low in efficiency, high in cost and large in data deviation are solved. And the test efficiency and the accuracy and reliability of test results are improved.

Description

Technical Field

[0001] This invention relates to the field of rock mechanics testing technology, and specifically to a method for continuous in-situ testing of rock mechanics parameters in a well. Background Technology

[0002] In fields such as oil and gas exploration and development, as well as geological engineering, obtaining accurate rock mechanics parameters is crucial for wellbore stability analysis, drilling engineering design, selection of completion methods, and formulation of fracturing construction plans.

[0003] Currently, commonly used methods for testing rock mechanics parameters mainly include laboratory testing and in-situ testing in mines. Laboratory testing typically requires extracting core samples from the well, processing them, and then conducting mechanical property tests in a laboratory environment to obtain parameters such as compressive strength, elastic modulus, and Poisson's ratio. However, this method has several limitations. On the one hand, the core sampling process may damage the rock, causing the test results to not accurately reflect the mechanical properties of the underground rock. On the other hand, the selection of core samples is random, resulting in point samples that cannot reflect the continuous rock mechanics properties of the entire formation. In-situ testing in mines, such as hydraulic fracturing, can reflect actual formation conditions, but the test site is still a single point, failing to reflect the continuous rock mechanics properties of the entire formation. Furthermore, the equipment is complex, the operation is time-consuming, and the cost is high, making it difficult to meet the needs for rapid and continuous testing. The limitations of existing methods are particularly pronounced in complex well conditions (such as deep wells and fractured formations). In addition, geophysical logging methods such as sonic logging and density logging can reflect some of the mechanical properties of rocks to a certain extent. However, these methods are mostly based on indirect physical quantity measurements and estimate rock mechanical parameters by establishing empirical models. The accuracy and reliability of their test results are affected by a variety of factors, resulting in large errors. Summary of the Invention

[0004] The purpose of this invention is to provide a method for in-situ continuous testing of rock mechanical parameters in wells. This method addresses the problems of commonly used rock mechanical parameter testing methods, which are mostly point samples and cannot reflect the continuous rock mechanical properties of the entire formation. Some testing methods involve complex equipment, time-consuming operation, and high costs, making it difficult to meet the needs of rapid and continuous testing. Alternatively, some methods rely on empirical models to estimate rock mechanical parameters, but the accuracy and reliability of the test results are affected by various factors, resulting in large errors.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for continuous in-situ testing of rock mechanical parameters in a well, characterized by the following specific steps: wellbore preparation, equipment preparation, equipment insertion into the well, pre-testing, testing operation, data processing and analysis, and result output. S1 Wellbore Preparation: ① Use a well gauge 5-8% smaller than the wellbore diameter and 1.5m in length to clean the well. The working weight fluctuation during the well cleaning process should be less than 10% to be considered qualified; ② In the target well, use a high-pressure water jet device to clean the well wall with a solution containing betaine and white oil to remove mud cake, oil stains and other impurities from the well wall surface, ensuring that the well wall surface is clean and flat for subsequent testing operations; S2 Equipment Preparation: Prepare a set of downhole continuous micro-etching testing equipment, which includes a continuous micro-etching tool, pressure sensor, displacement sensor, attitude adjustment mechanism, and data acquisition and processing system. The continuous micro-etching tool has an adjustable cutting edge angle and an adjustable control head, allowing for adjustments to the shape, size, and material of the control head according to testing requirements. The pressure sensor measures the pressure exerted by the control head on the wellbore rock during continuous micro-etching. The displacement sensor measures the displacement of the control head on the wellbore rock surface. The attitude adjustment mechanism adjusts the overall attitude of the device. The data acquisition and processing system collects data from the pressure and displacement sensors in real time and analyzes and processes the data. The intelligent closed-loop control drive system controls the micro-etching motion using a force feedback sensor and a motion parameter adjustment module. S3 Equipment Deployment: Connect the downhole continuous micro-etching test device to the transmission device, lower the test device into the well, and bring the device assembly to the predetermined position of the section to be tested. Adjust the attitude of the continuous micro-etching tool through the ground control system to ensure that the etcher is perpendicular to and in close contact with the rock surface of the well wall; use the information fed back by the angle sensor to ensure that the contact angle error is within ±0.5°. S4 Pre-test: Start the ground control system, select a 1-5m section above the target well section to begin testing, record data, process and analyze it. A relative error of ≤5% is considered acceptable data quality. Reposition the equipment to the starting test location and set the equipment parameters. S5 Test Operation: The ground control system is activated to control the continuous micro-etching tool to perform continuous micro-etching operations on the wellbore rock surface at a certain speed; the continuous micro-etching speed is set to 0.5-2 cm / s, and the initial pressure is set according to the estimated rock hardness range, with a pressure range of 0-1800 N; at the same time, the pressure sensor measures the normal pressure F applied by the control head to the wellbore rock in real time, the displacement sensor measures the displacement s of the control head on the wellbore rock surface and the continuous micro-etching depth h in real time, and the data acquisition and processing system collects the pressure F and displacement s data in real time and records the continuous micro-etching time t; S6 Data Processing and Analysis: Based on the collected data such as pressure F, displacement s, and time t, the parameters of continuous micro-etching are analyzed and processed using rock mechanics theory and related mathematical models to obtain rock mechanics parameters, specifically including: a. Rock hardness: Based on the average pressure F exerted on the control head during continuous micro-etching.av The contact area A between the control head and the rock is determined by the formula H=F. av / A calculates rock hardness H; b. Rock elastic modulus E: Calculation formula E=σ / ε l Where σ is the stress calculated based on the pressure and the continuous micro-etched area, and ε l The strain is calculated based on the rock surface displacement and the size of the contact area between the tool and the rock under the initial state; c. Rock Poisson's Ratio: The theoretical formula for calculating the rock Poisson's ratio, ν = -ε, is derived by combining data on the lateral and longitudinal deformation of the rock during continuous micro-etching. t / ε l , where ε t For transverse strain, ε l For longitudinal strain; d. Compressive strength σ c : Calculation formula σ c =k×F av / A; where F av The average pressure during the continuous micro-etching process is calculated by averaging the data collected by the pressure sensor; A is the cross-sectional area of ​​the continuous micro-etching, calculated based on the depth and length of the continuous micro-etching recorded by the displacement sensor; k is a correction coefficient related to the shape of the engraving tool and the characteristics of the rock, which is predetermined by a large number of indoor and outdoor experiments and has a value range of 0.8-1.2. e. Internal friction angle φ and cohesion c: Calculated by analyzing the rock fragmentation morphology at the edge of continuous micro-etching and combining the morphological-mechanical parameter correspondence established by discrete element simulation; S7 Results Output: Depending on the actual situation, 2-3 consecutive micro-etching tests need to be performed at different locations in the same test section. Each test is conducted at a different location with an interval of 15-25 mm to obtain multiple rock mechanical parameter data. Abnormal data with a deviation of more than 10% are removed. The mean and standard deviation of the parameters are calculated using statistical methods. The calculated rock mechanical parameters are stored and output through the data acquisition and processing system to provide data support for subsequent engineering design and analysis.

[0006] Furthermore, the concentration of the betaine-type white oil solution in S1 is 0.5%, and the structural formula of betaine is RC5H. 13 NPO5, where R is C 12 -C 18 alkyl.

[0007] Furthermore, the tool angle of the continuous micro-etching tool in S2 is adjustable from 20° to 80°, the pressure sensor range is 0-1800N, and the accuracy is ±0.02%FS; The control head includes replaceable conical, flat-bottomed cylindrical or spherical structures, made of diamond, cemented carbide or superhard ceramic, with a tip angle of 30°-90° and a diameter of 2-10mm.

[0008] Furthermore, the intelligent closed-loop control drive system can automatically adjust the feed speed of the control head based on real-time pressure data, control the scribing tool to continuously micro-etch along a preset trajectory, and ensure that the pressure fluctuation amplitude is ≤5% of the set value, thus ensuring the stability of the continuous micro-etching process. It also simultaneously collects pressure F, displacement s, and time t data to form a continuous test data sequence with a density ≥2000 points / m.

[0009] Furthermore, the displacement sensor, with a resolution of 0.01 mm, is also used to synchronously record the movement trajectory of the control head.

[0010] Furthermore, the downhole continuous micro-etching testing device is also equipped with a high-speed data acquisition system with a sampling frequency of 200Hz and an integrated edge computing module; The strain on the rock surface is monitored in real time using a micro-strain gauge integrated into the control head support, and the strain is calculated using the Poisson's ratio formula ν=-ε. t / ε l To obtain continuous Poisson's ratio values ​​along a continuous micro-etching path.

[0011] Furthermore, the downhole continuous micro-etching test device is lowered to the target well section. Through the multi-axis inertial measurement unit and hydraulic servo mechanism, the verticality deviation between the control head and the well wall surface is ≤0.5°, and a pre-contact pressure of 0-500N is maintained. The collected data underwent in-depth processing: ① A denoising algorithm combining wavelet transform and median filtering was used to eliminate noise interference with a frequency ≥50Hz; ② The elastic stage of the continuous micro-etching force-displacement curve was identified based on the dynamic time warping algorithm; ③ The continuous distribution of rock hardness modulus and rock elastic modulus was calculated using the contact mechanics model - Berkovich / Hertz model.

[0012] Furthermore, when calculating the elastic modulus of the rock, a piecewise linear regression algorithm is used to fit the initial linear segment of the continuous micro-etching force-displacement curve, with strain ≤0.1% and fitting error ≤2%.

[0013] Furthermore, the micro-strain monitoring module includes two sets of orthogonally arranged strain gauges, used to measure the transverse ε. l and longitudinal strain ε l The strain measurement accuracy reaches 10μm.

[0014] Furthermore, the testing equipment also includes a temperature and pressure compensation module, used to correct the impact of downhole temperatures ≥150℃ and pressures ≥60MPa on sensor accuracy.

[0015] The beneficial effects of this invention are as follows: This application utilizes downhole equipment to perform controllable continuous micro-etching on the wellbore rock, and combines it with a mechanical model to achieve in-situ rapid determination of rock mechanical parameters. This method can directly test the wellbore rock under wellbore conditions to obtain the rock's mechanical parameters, solving the problems of low efficiency, high cost, and large data deviation of traditional methods, and improving testing efficiency as well as the accuracy and reliability of test results.

[0016] Specifically, this method achieves in-situ dynamic testing of rock mechanical parameters through continuous downhole micro-etching, overcoming the limitations of discrete measurements; it automatically optimizes control head motion parameters and corrects noise data; and it is equipped with a temperature / pressure compensation module to adapt to complex downhole environments with high temperatures (≥150℃) and high pressures (≥60MPa). Field tests have verified that this method can control the measurement error of rock mechanical parameters to within 10%, and its testing efficiency is 80% higher than traditional core analysis. It provides continuous mechanical data support with millimeter-level resolution for wellbore stability assessment, drilling parameter optimization, completion process selection, and reservoir stimulation design, demonstrating significant engineering application value.

[0017] An adaptive continuous micro-etching device with an integrated intelligent closed-loop control drive system, combined with a pressure sensor with an accuracy of ±0.02%FS, a displacement sensor with a resolution of 0.01mm, and a high-speed data acquisition system with a maximum sampling frequency of 200Hz, ensures continuous micro-etching and accurately and synchronously acquires pressure, displacement, and strain data, forming a continuous data sequence with a density ≥2000 points / m. The rock hardness and elastic modulus are calculated using the Hertz model or a modified Berkovich model, and the Poisson's ratio is derived based on the transverse / longitudinal strain with an accuracy of 10μm monitored by orthogonal strain gauges. Finally, precise mechanical parameters are generated with a spatial resolution ≥0.1mm.

[0018] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a continuous micro-etching process.

[0020] Figure 2 This is a schematic diagram of the data processing flow. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Please see Figure 1-2 The method for continuous in-situ testing of rock mechanical parameters in a well, as shown in this application, includes the following steps: well preparation, equipment preparation, equipment insertion into the well, pre-testing, testing operation, data processing and analysis, and result output. S1 Wellbore Preparation: ① Use a well gauge 5-8% smaller than the wellbore diameter and 1.5m in length to clean the well. The working weight fluctuation during the well cleaning process should be less than 10% to be considered qualified; ② In the target well, use a high-pressure water jet device to clean the well wall with a solution containing betaine and white oil to remove mud cake, oil stains and other impurities from the well wall surface, ensuring that the well wall surface is clean and flat for subsequent testing operations; S2 Equipment Preparation: Prepare a set of downhole continuous micro-etching testing equipment, which includes a continuous micro-etching tool, pressure sensor, displacement sensor, attitude adjustment mechanism, and data acquisition and processing system. The continuous micro-etching tool has an adjustable cutting edge angle and an adjustable control head, allowing for adjustments to the shape, size, and material of the control head according to testing requirements. The pressure sensor measures the pressure exerted by the control head on the wellbore rock during continuous micro-etching. The displacement sensor measures the displacement of the control head on the wellbore rock surface. The attitude adjustment mechanism adjusts the overall attitude of the device. The data acquisition and processing system collects data from the pressure and displacement sensors in real time and analyzes and processes the data. The intelligent closed-loop control drive system controls the micro-etching motion using a force feedback sensor and a motion parameter adjustment module. S3 Equipment Deployment: Connect the downhole continuous micro-etching test device to the transmission device, lower the test device into the well, and bring the device assembly to the predetermined position of the section to be tested. Adjust the attitude of the continuous micro-etching tool through the ground control system to ensure that the etcher is perpendicular to and in close contact with the rock surface of the well wall; use the information fed back by the angle sensor to ensure that the contact angle error is within ±0.5°. S4 Pre-test: Start the ground control system, select a 1-5m section above the target well section to begin testing, record data, process and analyze it. A relative error of ≤5% is considered acceptable data quality. Reposition the equipment to the starting test location and set the equipment parameters. S5 Test Operation: The ground control system is activated to control the continuous micro-etching tool to perform continuous micro-etching operations on the wellbore rock surface at a certain speed; the continuous micro-etching speed is set to 0.5-2 cm / s, and the initial pressure is set according to the estimated rock hardness range, with a pressure range of 0-1800 N; at the same time, the pressure sensor measures the normal pressure F applied by the control head to the wellbore rock in real time, the displacement sensor measures the displacement s of the control head on the wellbore rock surface and the continuous micro-etching depth h in real time, and the data acquisition and processing system collects the pressure F and displacement s data in real time and records the continuous micro-etching time t; S6 Data Processing and Analysis: Based on the collected data such as pressure F, displacement s, and time t, the parameters of continuous micro-etching are analyzed and processed using rock mechanics theory and related mathematical models to obtain rock mechanics parameters, specifically including: a. Rock hardness: Based on the average pressure F exerted on the control head during continuous micro-etching. av The contact area A between the control head and the rock is determined by the formula H=F. av / A calculates rock hardness H; b. Rock elastic modulus E: Calculation formula E=σ / ε l Where σ is the stress calculated based on the pressure and the continuous micro-etched area, and ε lThe strain is calculated based on the rock surface displacement and the size of the contact area between the tool and the rock under the initial state; c. Rock Poisson's Ratio: The Poisson's ratio of a rock is calculated using specific experimental methods or theoretical formulas, combining data on the lateral and longitudinal deformation of the rock during continuous micro-etching. The theoretical formula for calculating the rock Poisson's ratio is ν = -ε. t / ε l , where ε t For transverse strain, ε l For longitudinal strain; d. Compressive strength σ c : Calculation formula σ c =k×F av / A; where F av The average pressure during the continuous micro-etching process is calculated by averaging the data collected by the pressure sensor; A is the cross-sectional area of ​​the continuous micro-etching, calculated based on the depth and length of the continuous micro-etching recorded by the displacement sensor; k is a correction coefficient related to the shape of the engraving tool and the characteristics of the rock, which is predetermined by a large number of indoor and outdoor experiments and has a value range of 0.8-1.2. e. Internal friction angle φ and cohesion c: Calculated by analyzing the rock fragmentation morphology at the edge of continuous micro-etching and combining the morphological-mechanical parameter correspondence established by discrete element simulation; S7 Results Output: Depending on the actual situation, 2-3 consecutive micro-etching tests need to be performed at different locations in the same test section. Each test is conducted at a different location with an interval of 15-25 mm to obtain multiple rock mechanical parameter data. Abnormal data with a deviation of more than 10% are removed. The mean and standard deviation of the parameters are calculated using statistical methods. The calculated rock mechanical parameters are stored and output through the data acquisition and processing system to provide data support for subsequent engineering design and analysis.

[0026] The concentration of the betaine-type white oil solution in S1 is 0.5%, and the structural formula of betaine is RC5H. 13 NPO5, where R is C 12 -C 18 alkyl.

[0027] The tool angle of the continuous micro-etching tool in S2 is adjustable from 20° to 80°, and the pressure sensor has a range of 0-1800N and an accuracy of ±0.02%FS. The control head includes replaceable conical, flat-bottomed cylindrical or spherical structures, made of diamond, cemented carbide or superhard ceramic, with a tip angle of 30°-90° and a diameter of 2-10mm.

[0028] The intelligent closed-loop control drive system can automatically adjust the feed speed of the control head according to real-time pressure data, control the scribing tool to continuously micro-etch along the preset trajectory, so that the pressure fluctuation amplitude is ≤5% of the set value, ensuring the stability of the continuous micro-etching process, and simultaneously collecting pressure F, displacement s, and time t data to form a continuous test data sequence with a density ≥2000 points / m.

[0029] The displacement sensor has a resolution of 0.01 mm and is also used to synchronously record the movement trajectory of the control head.

[0030] The downhole continuous micro-etching test device is also equipped with a high-speed data acquisition system with a sampling frequency of 200Hz and an integrated edge computing module; The strain on the rock surface is monitored in real time using a micro-strain gauge integrated into the control head support, and the strain is calculated using the Poisson's ratio formula ν=-ε. t / ε l To obtain continuous Poisson's ratio values ​​along a continuous micro-etching path.

[0031] The downhole continuous micro-etching test device is lowered to the target well section. Through the multi-axis inertial measurement unit and hydraulic servo mechanism, the verticality deviation between the control head and the well wall surface is ≤0.5°, and a pre-contact pressure of 0-500N is maintained. The collected data underwent in-depth processing: ① A denoising algorithm combining wavelet transform and median filtering was used to eliminate noise interference with a frequency ≥50Hz; ② The elastic stage of the continuous micro-etching force-displacement curve was identified based on the dynamic time warping algorithm; ③ The continuous distribution of rock hardness modulus and rock elastic modulus was calculated using the contact mechanics model - Berkovich / Hertz model.

[0032] When calculating the elastic modulus of rock, a piecewise linear regression algorithm is used to fit the initial linear segment of the continuous micro-etching force-displacement curve, with strain ≤0.1% and fitting error ≤2%.

[0033] The micro strain monitoring module contains two sets of orthogonally arranged strain gauges, used to measure transverse ε. l and longitudinal strain ε l The strain measurement accuracy reaches 10μm.

[0034] The testing equipment also includes a temperature and pressure compensation module, which is used to correct the impact of downhole temperature ≥150℃ and pressure ≥60MPa on sensor accuracy.

[0035] Example 1 A well in a central oilfield with a completion depth of 2300m needs rock mechanics parameter testing for the 1980-2200m section of the well. The actual drilling diameter for this section is 230-235mm.

[0036] (1) Well preparation: ① Use a Φ200mm well gauge with a length of 1.5m to clean the well, with the maximum reduction in suspended weight during the well cleaning process being 8%, and the well body quality being qualified; ② In the target well, use a high-pressure water jet device to clean the well wall. The medium is 2600L of white oil solution with 0.5% betaine added, which completely cleans away the mud cake, oil stains and other impurities on the surface of the well wall, and the surface of the well wall is clean and meets the requirements.

[0037] (2) Equipment preparation: Select a continuous micro-etching tool with a conical control head. The control head is made of cemented carbide, with a tip angle of 60° and a bottom diameter of 5mm. The pressure sensor has a measurement range of 0-500N and an accuracy of ±0.02FS. The displacement sensor has an accuracy of ±0.01mm. The data acquisition and processing system can acquire data at a frequency of 200Hz.

[0038] (3) Downhole operation: Start the armored cable test equipment of the ground power equipment and lower it into the well. After positioning and depth calibration, reach a depth of 2200m, the bottom of the section to be tested. Adjust the attitude of the continuous micro-etching tool through the ground control equipment. Use gyroscope and accelerometer to monitor the attitude of the tool in real time to ensure that the control head is perpendicular to the rock surface of the well wall and in close contact, and the contact pressure is maintained at about 30N.

[0039] (4) Pre-test: Record data in well section 2195-2200m, process and analyze it. The relative error is 3.8%, and the data quality is qualified. Reposition the equipment to 2200m and set the equipment parameters (parameters in the pre-test stage).

[0040] (5) Continuous micro-etching operation: The continuous micro-etching tool is controlled to perform linear scribing on the surface of the well wall rock at a speed of 4.5 mm / s. During the continuous micro-etching process, the pressure sensor measures the pressure applied by the scribing tool to the well wall rock in real time, the displacement sensor measures the movement displacement of the control head in real time, and the data acquisition and processing system collects and records relevant data in real time.

[0041] (6) Data Processing and Analysis: After data acquisition, the data acquisition and processing system processes the pressure and displacement data and plots a continuous micro-etching force-displacement curve. Through curve analysis, the average pressure F acting on the control head is calculated. av The resistance is 180N. Based on the dimensions of the control head, the contact area A between the control head and the rock is calculated to be 0.196 cm². 2The rock hardness H was calculated to be approximately 1020 MPa. During the elastic deformation stage of the continuous micro-etching force-displacement curve, the slope k of the curve was calculated. Combined with the geometric parameters of the control head in contact with the rock, the rock's elastic modulus E was calculated to be 30 GPa using the corresponding formula. Furthermore, by installing micro-strain gauges on the continuous micro-etching tool, the lateral and longitudinal deformation data of the rock during the continuous micro-etching process were measured, and the Poisson's ratio μ of the rock was calculated to be 0.25 using a specific formula.

[0042] (7) Results output: The calculated rock hardness, elastic modulus and Poisson's ratio and other mechanical parameters are stored in the data acquisition and processing system, and the test report is output through the printer to provide data support for the subsequent mining scheme design of the oil well.

[0043] Example 2 In a certain shale gas well, the vertical depth of the reservoir section is 2600m, and the horizontal section is 1080m long (depth measured: 2890-3970m). The actual drilling diameter of the horizontal section is 233-238mm. It is planned to conduct rock mechanics parameter testing on the 3720-3850m section of the well.

[0044] (1) Well preparation: ① Use a Φ200mm well gauge with a length of 1.5m to clean the well, with the maximum reduction in suspended weight during the well cleaning process being 10%, and the well body quality being qualified; ② In the target well, use a high-pressure water jet device to clean the well wall. The medium is 3000L of white oil solution with 0.5% betaine added, which completely cleans away the mud cake, oil stains and other impurities on the surface of the well wall, and the surface of the well wall is clean and meets the requirements.

[0045] (2) Equipment preparation: Replace with a flat-bottomed cylindrical control head with a diameter of 8mm and made of diamond composite material; the pressure sensor has a measurement range of 0-500N, the displacement sensor has a measurement accuracy of 0.01mm, the data acquisition and processing system has an acquisition frequency of 200Hz, the downhole tool is connected to the coiled tubing, and the coiled tubing is used to run the tool.

[0046] (3) Downhole operation: Start the ground power equipment and use coiled tubing to lower the test equipment into the well. After positioning and depth calibration, reach a depth of 3850m to the bottom of the section to be tested. Adjust the attitude of the continuous micro-etching tool through the ground control equipment. Use gyroscope and accelerometer to monitor the tool attitude in real time to ensure that the control head is perpendicular to the rock surface of the well wall and in close contact, and the contact pressure is maintained at about 1.5kN.

[0047] (4) Pre-test: Record data in well section 3845-3850m, process and analyze it. The relative error is 4.2%, and the data quality is qualified. Reposition the equipment to 3850m and set the equipment parameters (parameters in the pre-test stage).

[0048] (5) Continuous micro-etching operation: The continuous micro-etching tool is controlled to perform linear scribing on the surface of the wellbore rock at a speed of 4.0 mm / s. During the continuous micro-etching process, the pressure sensor measures the pressure applied by the scribing tool to the wellbore rock in real time, the displacement sensor measures the movement displacement of the control head in real time, and the data acquisition and processing system collects and records relevant data in real time.

[0049] (6) Data processing and analysis: The collected data were processed and analyzed, and the average pressure was calculated to be 135 N and the contact area A was 0.5024 cm². 2 The rock hardness H was calculated to be approximately 696.6 MPa; the rock elastic modulus E was calculated to be 25 GPa based on the slope of the elastic deformation stage curve and related formulas; and the Poisson's ratio μ of the rock was calculated to be 0.28 by measuring the transverse and longitudinal deformation data.

[0050] Results output: The rock mechanics parameters obtained from the test will be stored and output, providing an important basis for the formulation of shale gas fracturing construction plans.

[0051] In summary, this invention provides a method for in-situ continuous testing of rock mechanical parameters in wells. This method utilizes downhole equipment to perform controllable continuous micro-etching on the wellbore rock, combined with a mechanical model, to achieve rapid in-situ determination of rock mechanical parameters. This method can directly test the wellbore rock under wellbore conditions to obtain the rock's mechanical parameters, solving the problems of low efficiency, high cost, and large data deviation of traditional methods, and improving testing efficiency as well as the accuracy and reliability of test results.

[0052] Specifically, this method achieves in-situ dynamic testing of rock mechanical parameters through continuous downhole micro-etching, overcoming the limitations of discrete measurements; it automatically optimizes control head motion parameters and corrects noise data; and it is equipped with a temperature / pressure compensation module to adapt to complex downhole environments with high temperatures (≥150℃) and high pressures (≥60MPa). Field tests have verified that this method can control the measurement error of rock mechanical parameters to within 10%, and its testing efficiency is 80% higher than traditional core analysis. It provides continuous mechanical data support with millimeter-level resolution for wellbore stability assessment, drilling parameter optimization, completion process selection, and reservoir stimulation design, demonstrating significant engineering application value.

[0053] An adaptive continuous micro-etching device with an integrated intelligent closed-loop control drive system, combined with a pressure sensor with an accuracy of ±0.02%FS, a displacement sensor with a resolution of 0.01mm, and a high-speed data acquisition system with a maximum sampling frequency of 200Hz, ensures continuous micro-etching and accurately and synchronously acquires pressure, displacement, and strain data, forming a continuous data sequence with a density ≥2000 points / m. The rock hardness and elastic modulus are calculated using the Hertz model or a modified Berkovich model, and the Poisson's ratio is derived based on the transverse / longitudinal strain with an accuracy of 10μm monitored by orthogonal strain gauges. Finally, precise mechanical parameters are generated with a spatial resolution ≥0.1mm.

[0054] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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.

[0055] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for continuous in-situ testing of rock mechanical parameters in a well, characterized in that, The specific steps are as follows: wellbore preparation, equipment preparation, equipment entry into the well, pre-testing, testing operations, data processing and analysis, and result output; S1 Wellbore Preparation: ① Use a well gauge 5-8% smaller than the wellbore diameter and 1.5m in length to clean the well. The working weight fluctuation during the well cleaning process should be less than 10% to be considered qualified; ② In the target well, use a high-pressure water jet device to clean the well wall with a solution containing betaine and white oil to remove mud cake, oil stains and other impurities from the well wall surface, ensuring that the well wall surface is clean and flat for subsequent testing operations; S2 Equipment Preparation: Prepare a set of downhole continuous micro-etching testing equipment, which includes a continuous micro-etching tool, pressure sensor, displacement sensor, attitude adjustment mechanism, and data acquisition and processing system. The continuous micro-etching tool has an adjustable cutting edge angle and an adjustable control head, allowing for adjustments to the shape, size, and material of the control head according to testing requirements. The pressure sensor measures the pressure exerted by the control head on the wellbore rock during continuous micro-etching. The displacement sensor measures the displacement of the control head on the wellbore rock surface. The attitude adjustment mechanism adjusts the overall attitude of the device. The data acquisition and processing system collects data from the pressure and displacement sensors in real time and analyzes and processes the data. The intelligent closed-loop control drive system controls the micro-etching motion using a force feedback sensor and a motion parameter adjustment module. S3 Equipment Deployment: Connect the downhole continuous micro-etching test device to the transmission device, lower the test device into the well, and bring the device assembly to the predetermined position of the section to be tested. Adjust the attitude of the continuous micro-etching tool through the ground control system to ensure that the etcher is perpendicular to and in close contact with the rock surface of the well wall; use the information fed back by the angle sensor to ensure that the contact angle error is within ±0.5°. S4 Pre-test: Start the ground control system, select a 1-5m section above the target well section to begin testing, record data, process and analyze it. A relative error of ≤5% is considered acceptable data quality. Reposition the equipment to the starting test location and set the equipment parameters. S5 Test Operation: The ground control system is activated to control the continuous micro-etching tool to perform continuous micro-etching operations on the wellbore rock surface at a certain speed; the continuous micro-etching speed is set to 0.5-2 cm / s, and the initial pressure is set according to the estimated rock hardness range, with a pressure range of 0-1800 N; at the same time, the pressure sensor measures the normal pressure F applied by the control head to the wellbore rock in real time, the displacement sensor measures the displacement s of the control head on the wellbore rock surface and the continuous micro-etching depth h in real time, and the data acquisition and processing system collects the pressure F and displacement s data in real time and records the continuous micro-etching time t; S6 Data Processing and Analysis: Based on the collected data such as pressure F, displacement s, and time t, the parameters of continuous micro-etching are analyzed and processed using rock mechanics theory and related mathematical models to obtain rock mechanics parameters, specifically including: a. Rock hardness: Based on the average pressure F exerted on the control head during continuous micro-etching. av The contact area A between the control head and the rock is determined by the formula H=F. av / A calculates rock hardness H; b. Rock elastic modulus E: Calculation formula E=σ / ε l Where σ is the stress calculated based on the pressure and the continuous micro-etched area, and ε l The strain is calculated based on the rock surface displacement and the size of the contact area between the tool and the rock under the initial state; c. Rock Poisson's Ratio: The theoretical formula for calculating the rock Poisson's ratio, ν = -ε, is derived by combining data on the lateral and longitudinal deformation of the rock during continuous micro-etching. t / ε l , where ε t For transverse strain, ε l For longitudinal strain; d. Compressive strength σ c : Calculation formula σ c =k×F av / A; where F av The average pressure during the continuous micro-etching process is calculated by averaging the data collected by the pressure sensor; A is the cross-sectional area of ​​the continuous micro-etching, calculated based on the depth and length of the continuous micro-etching recorded by the displacement sensor; k is a correction coefficient related to the shape of the engraving tool and the characteristics of the rock, which is predetermined by a large number of indoor and outdoor experiments and has a value range of 0.8-1.

2. e. Internal friction angle φ and cohesion c: Calculated by analyzing the rock fragmentation morphology at the edge of continuous micro-etching and combining the morphological-mechanical parameter correspondence established by discrete element simulation; S7 Results Output: Depending on the actual situation, 2-3 consecutive micro-etching tests need to be performed at different locations in the same test section. Each test is conducted at a different location with an interval of 15-25 mm to obtain multiple rock mechanical parameter data. Abnormal data with a deviation of more than 10% are removed. The mean and standard deviation of the parameters are calculated using statistical methods. The calculated rock mechanical parameters are stored and output through the data acquisition and processing system to provide data support for subsequent engineering design and analysis.

2. The method for continuous in-situ testing of rock mechanical parameters in a well as described in claim 1, characterized in that, The concentration of the betaine-type white oil solution in S1 is 0.5%, and the structural formula of betaine is RC5H. 13 NPO5, where R is C 12 -C 18 alkyl.

3. The method for continuous in-situ testing of rock mechanical parameters in a well as described in claim 1, characterized in that, The tool angle of the continuous micro-etching tool in S2 is adjustable from 20° to 80°, and the pressure sensor has a range of 0-1800N and an accuracy of ±0.02%FS. The control head includes replaceable conical, flat-bottomed cylindrical or spherical structures, made of diamond, cemented carbide or superhard ceramic, with a tip angle of 30°-90° and a diameter of 2-10mm.

4. The method for continuous in-situ testing of rock mechanical parameters in a well as described in claim 1, characterized in that, The intelligent closed-loop control drive system can automatically adjust the feed speed of the control head according to real-time pressure data, control the scribing tool to continuously micro-etch along the preset trajectory, so that the pressure fluctuation amplitude is ≤5% of the set value, ensuring the stability of the continuous micro-etching process, and simultaneously collecting pressure F, displacement s, and time t data to form a continuous test data sequence with a density ≥2000 points / m.

5. The method for continuous in-situ testing of rock mechanical parameters in a well as described in claim 1, characterized in that, The displacement sensor has a resolution of 0.01 mm and is also used to synchronously record the movement trajectory of the control head.

6. The method for continuous in-situ testing of rock mechanical parameters in a well as described in claim 1, characterized in that, The downhole continuous micro-etching test device is also equipped with a high-speed data acquisition system with a sampling frequency of 200Hz and an integrated edge computing module; The strain on the rock surface is monitored in real time using a micro-strain gauge integrated into the control head support, and the strain is calculated using the Poisson's ratio formula ν=-ε. t / ε l To obtain continuous Poisson's ratio values ​​along a continuous micro-etching path.

7. The method for continuous in-situ testing of rock mechanical parameters in a well as described in claim 1, characterized in that, The downhole continuous micro-etching test device is lowered to the target well section. Through the multi-axis inertial measurement unit and hydraulic servo mechanism, the verticality deviation between the control head and the well wall surface is ≤0.5°, and a pre-contact pressure of 0-500N is maintained. The collected data underwent in-depth processing: ① A denoising algorithm combining wavelet transform and median filtering was used to eliminate noise interference with a frequency ≥50Hz; ② The elastic stage of the continuous micro-etching force-displacement curve was identified based on the dynamic time warping algorithm; ③ The continuous distribution of rock hardness modulus and rock elastic modulus was calculated using the contact mechanics model - Berkovich / Hertz model.

8. The method for continuous in-situ testing of rock mechanical parameters in a well as described in claim 1, characterized in that, When calculating the elastic modulus of rock, a piecewise linear regression algorithm is used to fit the initial linear segment of the continuous micro-etching force-displacement curve, with strain ≤0.1% and fitting error ≤2%.

9. The method for continuous in-situ testing of rock mechanical parameters in a well as described in claim 1, characterized in that, The micro strain monitoring module contains two sets of orthogonally arranged strain gauges, used to measure transverse ε. l and longitudinal strain ε l The strain measurement accuracy reaches 10μm.

10. A method for continuous in-situ testing of rock mechanical parameters in a well as described in claim 6, characterized in that, The testing equipment also includes a temperature and pressure compensation module, which is used to correct the impact of downhole temperature ≥150℃ and pressure ≥60MPa on sensor accuracy.

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