In-situ testing device and method for heat-water-force multi-field coupling parameters in ultra-deep high-pressure directional drilling

Abstract

This invention relates to the fields of geotechnical engineering and deep earth exploration technology, and discloses an in-situ testing device and method for multi-field coupled parameters of thermal-hydraulic-mechanical systems in ultra-deep high-pressure directional drilling. This method solves the problems of traditional testing methods, such as drill pipe axial force transmission leading to sealing failure, low efficiency of multi-parameter testing, neglect of multi-field coupling in data interpretation, and inability to quantify surrounding rock risks in real time. The testing device of this invention includes a multi-core armored cable, a downhole testing device, and a surface control and computing system. The downhole testing device is a central tube integrated structure, with an electrical control and communication module, upper and lower packers, and a multi-functional testing module integrated sequentially along the central tube. In application, the downhole device is lowered to the target formation, and the packers are hydraulically driven to set and form a sealed isolation section. Water is then injected into the sealed isolation section to induce fracturing, and multi-source data is collected simultaneously. After fracturing, fracture data is collected, and through data inversion and coupling correction, the plastic zone of the borehole wall is calculated and the risk is quantified. Finally, the device is retrieved.

Description

Technical Field

[0001] This invention relates to the fields of geotechnical engineering and deep earth exploration technology, specifically to an in-situ testing device and method for multi-field coupled parameters of thermal-hydraulic-mechanical systems in ultra-deep high-pressure directional boreholes. It is suitable for complex environments with depths exceeding 1500 meters and pore water pressures greater than 10 MPa, enabling the simultaneous acquisition of multiple parameters such as ground stress, permeability characteristics, and ground temperature. Background Technology

[0002] With the continuous advancement of deep-earth resource exploration and underground engineering construction, directional drilling projects are gradually extending to deeper underground areas and complex geological environments. This places higher demands on in-situ testing of multi-field coupled parameters of underground rock masses, and traditional geostress testing technologies such as hydraulic fracturing and casing removal are facing a series of significant challenges.

[0003] First, traditional testing techniques rely on the axial mechanical force transmission of the drill pipe to achieve packer setting. In ultra-deep holes, this method results in a large force attenuation due to the excessively long force transmission distance. To achieve a good setting effect, a large force needs to be applied to the force-applying end of the drill pipe, which makes the drill pipe prone to flexible deformation, leading to setting failure. Furthermore, it is difficult to resist high-pressure water inrush, resulting in poor sealing reliability.

[0004] Secondly, existing data acquisition technologies typically require multiple well runs to test parameters such as ground stress, permeability, and temperature, storing the collected data in a data acquisition card, and then importing the data from the data acquisition card into a computer after the drill pipe is retrieved. This method is not only time-consuming and inefficient, but also results in data that is outdated and cannot be analyzed or inverted in real time, making it difficult to reflect the true geological characteristics of the rock mass.

[0005] Furthermore, since parameters such as ground stress, permeability, and temperature cannot be collected in real time and synchronously during the data acquisition process, the traditional data interpretation process ignores the dynamic influence of the multi-field coupling effect of heat, water, and force on the stability of the surrounding rock, resulting in a certain degree of lag and insufficient accuracy of the calculation results.

[0006] Therefore, designing an in-situ testing device and method that can adapt to complex working conditions of ultra-deep high pressure, complete multi-parameter synchronous testing in a single well run, and achieve intelligent data inversion by combining multi-field coupling effects has become an urgent technical problem to be solved in the fields of geotechnical engineering and deep earth exploration. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide an in-situ testing device and method for multi-field coupled parameters of thermal-hydraulic-mechanical systems in ultra-deep high-pressure directional drilling, which solves the problems of axial force transmission of drill pipe leading to sealing failure, low efficiency of multi-parameter testing, neglect of multi-field coupling in data interpretation, and inability to quantify surrounding rock risk in real time in traditional testing.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0009] On the one hand, the present invention provides an in-situ testing device for multi-field coupling parameters of thermal-hydraulic-mechanical systems in ultra-deep high-pressure directional drilling, including: a multi-core armored cable, a downhole testing device, and a surface control and computing system;

[0010] One end of the multi-core armored cable is connected to the ground control and computing system for communication, and the other end is connected to the electrical control and communication module of the downhole testing device for electrical communication.

[0011] The downhole testing device is a central tube integrated structure, which integrates an electrical control and communication module, an upper packer, a multi-functional testing module and a lower packer in sequence from top to bottom along the central tube axis. The upper packer and the lower packer are coaxially sleeved on the outside of the central tube. After setting, they form a sealed isolation section between the upper packer, the lower packer and the borehole wall for in-situ testing.

[0012] The central tube has an axial water injection channel inside, and a high-pressure water injection hole connected to the water injection channel is opened on the tube wall of the central tube, and the high-pressure water injection hole is located inside the sealed isolation section.

[0013] The upper and lower packers have the same structure, both including an upper piston, a lower piston, and a rubber sleeve. The rubber sleeve is sealed on the outside of the upper and lower pistons, with its two ends connected to the ends of the upper and lower pistons respectively. A sealed chamber is formed between the inner side of the rubber sleeve and the outer wall of the central tube. Each packer's upper and lower pistons are equipped with corresponding one-way hydraulic locks, and each packer is equipped with a pressure adaptive balancing valve. One end of the pressure adaptive balancing valve is connected to the water in the borehole, and the other end is connected to the sealed chamber of the rubber sleeve of the corresponding packer. It is used to introduce high-pressure water from the borehole as a balancing medium to dynamically adjust the pressure difference inside and outside the rubber sleeve.

[0014] The multifunctional testing module includes an ultrasonic scanning unit, a temperature sensor, a pressure sensor, and a flow meter that are electrically connected to the electronic control and communication module.

[0015] In this solution, based on the aforementioned device structure design, the use of a double packer seal and independent hydraulic drive allows for free adjustment of the pressure difference between the inside and outside of the packer under high-pressure water inrush conditions, solving the sealing failure problem in ultra-deep, high-pressure water inrush environments. The integrated layout enables a single wellbore run to complete the entire testing process, significantly improving operational efficiency. The collaborative work of multi-functional testing modules enables simultaneous acquisition of multiple parameters and precise observation of fracture morphology. The independent design of the hydraulic flow channel and water injection channel ensures the coordinated and stable operation of each functional module. The overall structure closely matches the actual working conditions of ultra-deep, high-pressure directional drilling, ensuring both the safety and efficiency of testing operations while improving the accuracy and completeness of test data. This provides reliable hardware support for the inversion of thermo-hydraulic-mechanical multi-field coupled parameters and early warning of surrounding rock stability, effectively addressing many pain points of traditional testing devices in deep-earth engineering applications.

[0016] On the other hand, based on the above-mentioned testing device, the present invention also provides an in-situ testing method for multi-field coupled parameters of thermal-hydraulic-mechanical systems in ultra-deep high-pressure directional drilling, applied to the above-mentioned testing device, the method comprising the following steps:

[0017] S1. Lower the downhole testing device to the target formation using a multi-core armored cable;

[0018] S2. The ground control and computing system controls and drives the upper and lower packers to set, forming a sealed isolation section;

[0019] S3. The ground control and calculation system starts the high-pressure pump and injects water into the sealed isolation section through the water injection channel and high-pressure water injection hole to induce fracturing, and triggers the ultrasonic scanning unit to acquire the morphological data of the hole wall crack in real time; and simultaneously collects fracturing curve, geothermal gradient and pore water pressure data during the fracturing process;

[0020] S4. Map the morphological data of the borehole wall cracks to the borehole coordinate system and calculate the crack deflection angle;

[0021] S5. Input the fracturing curve, fracture deflection angle, geothermal gradient, and pore water pressure multi-source data into the deep learning model, combine iteratively solve the three-dimensional geostress balance equations, invert the three-dimensional geostress and permeability coefficient tensors, and complete the thermal-hydraulic-mechanical coupling correction.

[0022] S6. Construct a thermo-hydraulic-mechanical coupling model, substitute the coupled and corrected three-dimensional geostress and permeability coefficient tensors into the thermo-hydraulic-mechanical coupling model, calculate the distribution of the plastic zone in the borehole wall, and quantify the rockburst / water inrush risk level based on the distribution of the plastic zone in the borehole wall.

[0023] S7. Trigger the one-way hydraulic lock to release pressure. After the rubber sleeve resets, the downhole test device is retrieved to the surface via a multi-core armored cable.

[0024] This solution employs fluid pressure to drive packer setting, fundamentally addressing the issue of packer failure caused by drill pipe deformation in ultra-deep holes. It integrates electrical control, packer, and testing modules into a single downhole device, enabling a single downhole run to complete the entire process of positioning, fracturing, multi-parameter acquisition, fracture observation, inversion interpretation, and risk assessment. This replaces the traditional method of multiple downhole runs for single-parameter testing, significantly improving operational efficiency. Furthermore, it introduces 3D fracture data obtained through ultrasonic scanning as physical constraints, combining this with a deep learning model to solve tensors and perform thermo-hydraulic-mechanical coupling correction. This overcomes the shortcomings of traditional interpretations that neglect multi-field coupling, improving parameter accuracy. By constructing a coupled model to calculate the plastic zone and quantify risks, it extends the process from parameter testing to safety early warning, meeting the safety requirements of deep-earth engineering construction.

[0025] Furthermore, in step S1, during the process of lowering the downhole testing device using a multi-core armored cable, the position of the downhole testing device is dynamically calibrated based on the three-dimensional trajectory data of the borehole, achieving millimeter-level positioning of the target layer.

[0026] In this scheme, the positioning error caused by borehole trajectory deviation is eliminated by relying on the three-dimensional trajectory data of the borehole, so that fracturing and parameter testing are carried out in the preset target geological layer. This ensures that the collected multi-source data can truly reflect the rock mass characteristics of the target layer and provide accurate basic data for subsequent inversion interpretation.

[0027] Furthermore, step S2 also includes: introducing high-pressure water from inside the hole into the sealed chamber of the rubber tube in real time through a pressure adaptive balancing valve, and dynamically adjusting the pressure difference inside and outside the rubber tube.

[0028] In this solution, the pressure adaptive balancing valve uses high-pressure water inside the borehole as the balancing medium to dynamically adjust the pressure difference inside and outside the rubber sleeve. It does not rely on drill rod axial force compensation. Even under ultra-deep high-pressure water inrush conditions, it can maintain a tight fit between the rubber sleeve and the borehole wall, ensuring the sealing effect of the isolation section and avoiding fracturing failure and data acquisition errors caused by high-pressure water leakage.

[0029] Furthermore, in step S3, the morphological data of the hole wall cracks includes the geometric contour and spatial distribution data of the hole wall cracks.

[0030] In step S4, the geometric contour and spatial distribution data of the borehole wall cracks obtained by ultrasonic scanning are mapped to the borehole coordinate system, and the deflection angle of the cracks relative to the borehole axis is calculated, based on the three-dimensional trajectory information of the borehole.

[0031] In this scheme, ultrasonic scanning is initiated simultaneously during the water injection fracturing process to collect morphological data of the cracks in real time during their formation and propagation, rather than observing them after fracturing is completed. This effectively avoids morphological changes in the cracks caused by stress redistribution in the rock mass, ensuring that the acquired crack data is synchronized with the fracturing process, and providing a more realistic and accurate basis for calculating the crack deflection angle.

[0032] Furthermore, in step S5, the fracturing curve, fracture deflection angle, geothermal gradient, and pore water pressure multi-source data are input into the deep learning model. Combined with iterative solving of the three-dimensional geostress equilibrium equations, the three-dimensional geostress and permeability coefficient tensors are obtained through inversion. The process of completing the thermal-hydraulic-mechanical coupling correction includes:

[0033] The fracturing curve features, fracture deflection angle, borehole trajectory parameters, regional geological structure data, geothermal gradient, and pore water pressure data are input into a deep learning model pre-trained on a historical fracturing test dataset. Regional geological statistics are used as the initial iteration values ​​of geostress. The deep learning model is then used to calculate and output the initial solution of the geostress tensor.

[0034] The initial solution is substituted into the three-dimensional geostress equilibrium equations and iteratively solved to obtain the three-dimensional geostress tensor. The permeability coefficient tensor is then obtained by combining the permeability pressure decay curve.

[0035] Finally, based on geothermal gradient and pore water pressure data, the calculated three-dimensional geostress tensor and permeability coefficient tensor are corrected by thermal-hydraulic-mechanical coupling.

[0036] In this scheme, multi-source data is input into a deep learning model pre-trained on historical datasets. The initial solution of the geostress tensor is first obtained, and then the initial solution is substituted into the three-dimensional geostress equilibrium equations for iterative solution. This combines the rapid solution advantage of the deep learning model with the theoretical accuracy advantage of the equilibrium equations, improving the efficiency and accuracy of geostress tensor solution. The permeability coefficient tensor is solved step by step using the osmotic pressure decay curve. Then, geothermal gradient and pore water pressure data are introduced to perform thermal-hydraulic-mechanical coupling correction on the two tensors, effectively eliminating the disturbance effects of thermal field and seepage field on tensor parameters.

[0037] Furthermore, the process of substituting the initial solution of the geostress tensor into the three-dimensional geostress equilibrium equations for iterative solution includes:

[0038] Based on the initial solution of the geostress tensor, the residuals between the theoretical fracturing pressure and the actual fracturing pressure, and the deviation between the theoretical fracture deflection angle and the measured value are calculated. The model solution weights are adjusted according to the residuals and deviations through the backpropagation mechanism of the deep learning model, and the iterative value of the geostress tensor is updated. The updated iterative value is substituted back into the three-dimensional geostress equilibrium equations until the residuals and deviations meet the convergence conditions, and the calculated three-dimensional geostress tensor is output.

[0039] In this scheme, the residuals and deviations between the theoretical and measured values ​​are calculated based on the initial solution of the geostress tensor. The solution weights are adjusted according to the residuals and deviations through the backpropagation mechanism of the deep learning model. The updated iterative values ​​are then substituted into the equilibrium equations and solved again, forming a closed loop of "solution-comparison-correction-re-solution". This allows the solution results of the geostress tensor to be optimized step by step, effectively avoiding the distortion of the final results caused by the deviation of the initial solution.

[0040] Furthermore, the convergence condition of the residual is the fracturing pressure residual. The convergence condition for the deviation is the crack deflection angle deviation. .

[0041] In this scheme, by clarifying the quantitative convergence criteria for iterative solution of geostress tensor, specific thresholds are set for the deviation of fracturing pressure residual and fracture deflection angle, ensuring that the geostress tensor after iterative solution meets the preset accuracy requirements, avoiding the problem of insufficient solution accuracy due to the lack of clear convergence criteria, and providing high-precision geostress tensor parameters for subsequent coupling correction and risk assessment.

[0042] Furthermore, in step S6, the constructed thermal-hydraulic-mechanical coupling model is as follows:

[0043] ;

[0044] in, This represents the coupled geostress tensor. This represents the initial geostress tensor; This represents the stress disturbance tensor caused by temperature changes in the rock mass. ;

[0045] in, The coefficient of thermal expansion of the rock mass; It is the elastic modulus; This refers to the change in temperature. Poisson's ratio;

[0046] This is the stress disturbance tensor caused by pore water pressure. ;

[0047] in, Pore ​​water pressure; The pore water pressure coefficient characterizes the effect of pore water pressure on the rock and soil skeleton.

[0048] In this scheme, the constructed coupled model includes thermal field, seepage field, and stress field equations, which correspond to the mutual influence of geothermal temperature, pore water pressure, and geostress, respectively. The coupling effect of the three fields is incorporated into a unified theoretical model, avoiding the problem that a single field equation cannot reflect the true characteristics of the rock mass. This allows subsequent tensor calculations and corrections to fully consider the coupling disturbances of the three fields, thereby improving the accuracy of parameter calculations.

[0049] Furthermore, in step S6, the process of calculating the distribution of the plastic zone on the hole wall includes:

[0050] Based on the Mohr-Coulomb yield criterion, the distribution range and depth of the plastic zone of the rock mass around the borehole wall are calculated by substituting the coupled and corrected three-dimensional geostress and permeability coefficient tensors.

[0051] The Mohr-Coulomb yield criterion is characterized by a crack propagation constraint, and its expression is as follows:

[0052] ;

[0053] This is the calculated value of the Mohr-Coulomb yield function; Shear stress; Normal stress; It represents the cohesion of the soil and rock mass; The friction angle within the rock and soil is denoted as .

[0054] In this scheme, the distribution range and depth of the plastic zone in the borehole wall are calculated based on the Mohr-Coulomb yield criterion. This criterion is a classic theoretical basis for rock mass failure judgment, making the calculation of the plastic zone more scientific and accurate, and providing reliable theoretical support for the quantification of rockburst / water inrush risk in the surrounding rock.

[0055] The beneficial effects of this invention are:

[0056] (1) Improve the reliability of the setting seal:

[0057] Abandoning the traditional axial force transmission method for setting the drill pipe, this method uses fluid pressure to drive a bidirectional piston to squeeze the rubber sleeve to achieve fixed-point setting. Combined with a pressure adaptive balance valve to dynamically adjust the pressure difference inside and outside the rubber sleeve, it completely eliminates the interference of drill pipe flexible deformation. It can still achieve long-term reliable sealing under complex working conditions such as high water inflow, ultra-deep holes, and large-angle holes, thus improving the test success rate.

[0058] (2) Improve testing efficiency:

[0059] In the structural design of the testing device, the modular and integrated design of the downhole device enables the completion of the entire process of target formation positioning, hydraulic setting, water injection fracturing, multi-parameter synchronous acquisition, fracture morphology acquisition, multi-field coupling inversion, and risk quantification assessment in a single well run. This replaces the traditional single-parameter testing mode that requires multiple well runs, reduces the number of drilling operations, lowers construction costs, and improves overall testing efficiency.

[0060] (3) Improve the accuracy of test data:

[0061] The testing device integrates a high-precision fiber optic temperature sensor, a high-frequency pressure sensor, and a flow meter. It achieves spatiotemporal synchronous acquisition of thermal, water, and force data through hardware-level clock synchronization, eliminating time deviations in multi-source data. Combined with ultrasonic scanning to obtain crack morphology data, it provides accurate physical constraints for stress inversion. At the same time, considering the borehole trajectory deviation and the multi-field coupling effect of thermal-water-force, it significantly improves the accuracy of tensor calculations such as geostress and permeability coefficient through deep learning model iteration and coupling correction.

[0062] (4) Real-time early warning of surrounding rock risk:

[0063] A complete thermo-hydraulic-mechanical multi-field coupling model is constructed. The distribution of the plastic zone in the borehole wall is calculated by combining the Mohr-Coulomb yield criterion. The risk levels of rock bursts and water inrushes are quantified and safety warning thresholds are defined. By combining parameter testing with surrounding rock stability evaluation, real-time and accurate early warning of surrounding rock risks in deep earth engineering can be achieved, effectively improving the safety of deep earth engineering construction.

[0064] (5) Intelligent data interpretation:

[0065] By introducing a deep learning model and pre-training it with a historical fracturing dataset, intelligent inversion calculation of multi-source data is achieved. Through iterative optimization and residual convergence judgment, the efficiency and accuracy of data interpretation are improved, making up for the shortcomings of traditional data interpretation, such as lag and neglect of multi-field coupling, and realizing the upgrade from single-parameter testing to intelligent inversion of multi-field coupling. Attached Figure Description

[0066] Figure 1 This is a schematic diagram of the in-situ testing device for multi-field coupling parameters of ultra-deep high-pressure directional drilling in an embodiment of the present invention.

[0067] Figure 2 This is a flowchart of the in-situ testing method for multi-field coupling parameters of ultra-deep high-pressure directional drilling in an embodiment of the present invention.

[0068] Figure 3 This is a flowchart illustrating the multi-source data inversion process in an embodiment of the present invention.

[0069] Figure 4 This is a flowchart of the risk quantification assessment in an embodiment of the present invention.

[0070] Figure 1Explanation of markings: 1 is a multi-core armored cable; 2 is a downhole testing device; 3 is a surface control and calculation system; 4 is an upper piston; 5 is a lower piston; 6 is a rubber sleeve; 7 is a one-way hydraulic lock; 8 is a pressure adaptive balance valve; 9 is a water injection channel; 10 is a high-pressure water injection hole; 11 is a multi-functional testing module; 12 is an ultrasonic scanning unit. Detailed Implementation

[0071] This invention aims to provide an in-situ testing device and method for multi-field coupled parameters of thermal-hydraulic-mechanical systems in ultra-deep, high-pressure directional boreholes. It addresses the problems of traditional ultra-deep borehole testing techniques, such as drill pipe axial force transmission leading to sealing failure, the need for multiple downhole tests for multiple parameters resulting in low efficiency, and the inability to interpret data ignoring the effects of multi-field coupling and trajectory deviation, thus failing to quantify surrounding rock risks in real time. The core idea is to abandon the traditional axial force transmission method for sealing and innovatively adopt a fluid pressure-driven, axial force-free hydraulic sealing technology, coupled with a pressure-adaptive balancing valve, effectively solving the technical challenge of packer sealing failure under ultra-deep, high-pressure water inrush conditions. Through integrated and modular design of the downhole testing device, it enables a single downhole run to complete the entire testing process, including multi-field parameter acquisition, geostress inversion, plastic zone calculation, and risk assessment, thus overcoming the pain points of traditional testing methods requiring multiple downhole runs and resulting in low efficiency. It integrates high-precision multi-parameter synchronous acquisition, three-dimensional fracture morphology physical constraints, and deep learning model iterative solutions. Key technologies such as thermal-hydraulic-mechanical multi-field coupling correction are employed to improve the accuracy of multi-field coupling parameter calculation, overcoming the shortcomings of traditional data interpretation that ignore multi-field coupling effects and borehole trajectory deviations, leading to distorted calculation results. Ultimately, by constructing a complete thermal-hydraulic-mechanical coupling model, in-situ testing of multi-field coupling parameters is organically combined with borehole wall plastic zone calculation and quantitative assessment of surrounding rock burst / water inrush risk. This achieves an integrated closed loop from in-situ testing of multi-field coupling parameters to real-time early warning of surrounding rock stability in deep-earth engineering, providing accurate geomechanical parameter support and scientific safety evaluation basis for the safe construction of ultra-deep high-pressure directional drilling projects.

[0072] The present invention will now be described in more detail with reference to the accompanying drawings and embodiments.

[0073] This embodiment first provides an in-situ testing device for multi-field coupled parameters of thermal-hydraulic-mechanical systems in ultra-deep high-pressure directional drilling. (See also...) Figure 1 It includes: a multi-core armored cable 1, a downhole testing device 2, and a surface control computing system 3;

[0074] The ground control computing system 3 is connected to an independent hydraulic pipeline and a high-pressure pump. One end of the multi-core armored cable 1 is connected to the ground control computing system 3 for communication, and the other end is connected to the electrical control communication module of the downhole testing device 2. The independent hydraulic pipeline is connected to the hydraulic flow channel of the downhole testing device 2 and is used to deliver high-pressure fluid to drive the pistons of the upper and lower packers. The high-pressure pump is connected to the water injection channel of the central pipe and is used to deliver high-pressure water to carry out hydraulic fracturing.

[0075] The downhole testing device 2 uses the central tube as the installation reference, and all components are integrated and arranged in an integrated manner. Along the axial direction of the central tube from the top to the bottom, it integrates an electrical control and communication module, an upper packer, a multi-functional testing module 11, and a lower packer. The upper packer and the lower packer have the same structure and are coaxially sleeved on the outside of the central tube. After setting, they form a sealed isolation section between the upper packer, the lower packer, and the borehole wall for in-situ testing.

[0076] The central tube has an axial water injection channel 9 inside, and a high-pressure water injection hole 10 connected to the water injection channel 9 is opened on the tube wall of the central tube. The high-pressure water injection hole 10 is located in the sealing isolation section between the upper packer and the lower packer, and is used to inject high-pressure water into the sealing isolation section to carry out hydraulic fracturing.

[0077] The upper packer and the lower packer each include an upper piston 4, a lower piston 5, and a rubber sleeve 6 coaxially sleeved on the outside of the central tube; the upper piston 4 and the lower piston 5 are respectively connected to the upper and lower ends of the rubber sleeve 6; the rubber sleeve 6 is sleeved on the outside of the upper piston 4 and the lower piston 5, and its two ends are respectively sealed to the ends of the upper piston 4 and the lower piston 5, forming a sealed chamber between the inner side of the rubber sleeve 6 and the outer wall of the central tube.

[0078] Each packer has an upper piston 4 and a lower piston 5 equipped with a one-way hydraulic lock 7, which is used to maintain pressure. Each packer is also equipped with a pressure adaptive balancing valve 8. One end of the pressure adaptive balancing valve 8 is connected to the water in the borehole through a water injection channel 9, and the other end is connected to the rubber sleeve sealing chamber of the corresponding packer. It is used to introduce high-pressure water from the borehole as a balancing medium to dynamically adjust the pressure difference inside and outside the rubber sleeve 6.

[0079] The multifunctional test module 11 is coaxially sleeved on the outside of the central tube and located in the sealed isolation section between the upper packer and the lower packer. The multifunctional test module includes an ultrasonic scanning unit 12 arranged circumferentially along the central tube, as well as a high-precision fiber optic temperature sensor, a high-frequency pressure sensor, and a flow meter embedded inside the central tube.

[0080] The ultrasonic scanning unit 12 is used to directionally emit ultrasonic beams toward the borehole wall and receive reflected echo signals during the hydraulic fracturing process, thereby acquiring the geometric contour and spatial distribution data of the borehole wall cracks.

[0081] The high-precision fiber optic temperature sensor, high-frequency pressure sensor, flow meter, and ultrasonic scanning unit 12 are all electrically connected to the electronic control and communication module to achieve synchronous acquisition and data transmission of multiple parameters.

[0082] Based on the above-mentioned testing device, this embodiment also provides an in-situ testing method for multi-field coupled parameters of thermo-hydraulic-mechanical systems in ultra-deep high-pressure directional drilling. The implementation process is described in [link to implementation details]. Figure 2 The implementation process includes the following:

[0083] S1. Device placement and precise positioning:

[0084] In this step, the downhole testing equipment is precisely lowered to the preset target layer to eliminate the layer positioning error caused by borehole trajectory deviation, ensuring that the test accurately corresponds to the target geological body and providing a basis for subsequent tests.

[0085] Specifically, the downhole testing device 2, which integrates an electrical control and communication module, a packer, and a testing module, is slowly lowered into the borehole via a multi-core armored cable 1. During the lowering process, the ground control and computing system 3 receives the three-dimensional trajectory data of the borehole and the position data of the downhole device in real time. Based on the three-dimensional trajectory data of the borehole, the position of the downhole device is dynamically calibrated to achieve millimeter-level positioning of the target layer.

[0086] S2. Hydraulically driven setting seal:

[0087] In this step, a hydraulically driven packer forms a sealed isolation section at the target layer to resist ultra-deep high-pressure water inrush, prevent high-pressure water leakage during fracturing, and ensure the smooth progress of fracturing and parameter acquisition.

[0088] Specifically, the ground control computing system 3 issues a setting command and delivers high-pressure fluid to the upper and lower packers of the downhole test device 2 through an independent hydraulic pipeline. The high-pressure fluid drives the upper piston 4 and lower piston 5 of the packer to squeeze the rubber cylinder 6 in opposite directions, causing the rubber cylinder 6 to expand radially and fit tightly against the borehole wall. When the pressure of the rubber cylinder 6 against the wall reaches the preset pressure, the one-way hydraulic lock 7 is automatically triggered and pressure-holding seal is achieved, initially forming a test isolation section isolated from the outside world.

[0089] Meanwhile, the pressure adaptive balancing valve 8 introduces high-pressure water into the orifice in real time as a balancing medium, dynamically detects and adjusts the pressure difference inside and outside the rubber sleeve 6, so that the rubber sleeve 6 always maintains radial expansion stability in a high-flow water environment of more than 10MPa.

[0090] This step eliminates the traditional axial force transmission mechanism, achieving fixed-point setting solely through fluid pressure, thus completely eliminating the interference of drill pipe flexibility deformation on setting. Furthermore, the setting of the pressure adaptive balance valve 8 fundamentally solves the sealing failure problem caused by the imbalance of internal and external pressure differences in traditional packers. It eliminates the need to rely on drill pipe axial force compensation, and can still achieve long-term reliable sealing even in complex working conditions such as ultra-deep holes and large-angle holes.

[0091] S3. Water injection fracturing and simultaneous acquisition of multiple parameters:

[0092] This step involves hydraulic fracturing of the target stratum rock mass while simultaneously acquiring raw data related to heat, water, and force, thus integrating fracturing and data acquisition to ensure the spatiotemporal matching of the data.

[0093] Specifically, the ground control computing system 3 starts the high-pressure pump, and high-pressure water is continuously injected into the sealed isolation section formed by the packer through the water injection channel 9 and the high-pressure water injection hole 10 to perform hydraulic fracturing on the target layer rock mass; during the fracturing process, the ultrasonic scanning unit 12 of the multi-functional test module 11 is triggered simultaneously to emit ultrasonic beams directionally towards the borehole wall and receive reflected echo signals to obtain the geometric contour and spatial distribution data of the borehole wall cracks in real time.

[0094] Meanwhile, the high-precision fiber optic temperature sensor, high-frequency pressure sensor, and flow meter in the multi-functional test module are synchronized by a hardware-level clock to collect data such as pressure-time curves, geothermal gradients, and osmotic pressure decay curves in real time, and transmit all data to the ground control and computing system 3 in real time through a multi-core armored cable 1.

[0095] This step enables simultaneous fracturing and fracture observation, as well as multi-parameter acquisition, avoiding errors in fracture morphology caused by the time intervals of traditional step-by-step operations. Hardware-level clock synchronization can eliminate time deviations in multi-source data, ensuring the spatiotemporal matching of parameters such as geothermal gradient, fracturing pressure changes, and osmotic pressure decay, providing high-fidelity raw data for subsequent thermo-hydraulic-mechanical coupling inversion.

[0096] S4. Crack deflection angle calculation:

[0097] This step obtains accurate three-dimensional morphological data of the hydraulic fracturing fractures, providing physical constraints for geostress inversion and improving the accuracy of subsequent geostress tensor calculations.

[0098] Specifically, the ground control calculation system 3 combines the three-dimensional trajectory information of the borehole and maps the borehole wall morphology data obtained by ultrasonic scanning to the borehole coordinate system. Through spatial geometric calculation (the specific calculation method is existing technology and will not be elaborated here), the deflection angle of the fracture relative to the borehole axis is obtained. This deflection angle is a key physical constraint for subsequent three-dimensional geostress tensor inversion, and it is also the core basis for verifying the direction of hydraulic fracture propagation and improving the accuracy of thermal-hydraulic-mechanical multi-field coupling parameter inversion. Ultimately, it provides high-precision geomechanical basic data for borehole wall plastic zone calculation and rockburst / water inrush risk quantification.

[0099] S5. Intelligent Inversion of Multi-Field Coupled Parameters:

[0100] This step calculates the three-dimensional geostress and permeability tensor, and eliminates the disturbances of temperature and pore water pressure through thermal-hydraulic-mechanical coupling correction to obtain coupling parameters that fit the actual geological conditions.

[0101] Specifically, the process for multi-source parameter inversion can be found in [link to documentation]. Figure 3 The implementation process includes the following:

[0102] By inputting fracturing curve characteristics, fracture deflection angles, borehole trajectory parameters, and regional geological structure data, a three-dimensional geostress equilibrium equation set is constructed. Based on elasticity theory, the geostress tensors (σ1, σ2, σ3) are treated as unknowns. The Coulomb-Mohr criterion for fracture propagation and the linear elastic fracture mechanics conditions are combined to establish equation constraints. Since the three-dimensional geostress equilibrium equations are conventional equations in existing technology, the specific form of the equation set will not be described here.

[0103] The deep learning model was pre-trained using a historical fracturing test dataset. The model output layer corresponds to six independent components (σ11, σ22, σ33, σ12, σ13, σ23) of the geostress tensor. Regional geological statistics were used as the initial iterative values ​​of geostress and substituted into the equations for the first solution.

[0104] Calculate the residual between theoretical fracturing pressure and actual fracturing pressure. , Indicates the theoretical fracturing pressure; Indicates the actual fracturing pressure;

[0105] Simultaneously, the deviations between the theoretical crack deflection angle and the measured value were compared. Through the backpropagation mechanism of the deep learning model, based on the residual ( , Adjust the weighting coefficients of the geostress tensor components and update the iterative values. Repeat the above process until the residuals satisfy the convergence condition. , At this point, the output geostress tensor is the preliminary inversion result.

[0106] By introducing synchronously acquired geothermal and pore water pressure data, stress field disturbances caused by temperature changes are corrected based on thermoelastic theory. , The coefficient of thermal expansion is... For elastic modulus, It is Poisson's ratio.

[0107] The influence of pore water pressure on effective stress was corrected based on the theory of pore elasticity. , For effective stress, The pore water pressure is used to obtain the coupled and corrected geostress tensor.

[0108] Finally, by combining the permeability pressure decay curve after fracturing, Darcy's law and radial flow model are used, with the geostress tensor as a constraint condition, to solve the permeability coefficient tensor of the rock mass and complete the multi-parameter synchronous inversion.

[0109] S6. Risk Quantification and Real-time Early Warning:

[0110] This step involves constructing a complete thermo-hydraulic-mechanical coupling model to calculate the distribution of the plastic zone in the borehole wall, thereby enabling quantitative assessment and real-time early warning of the risk of rockburst / water inrush in the surrounding rock, and providing a basis for the safety of deep-earth engineering construction.

[0111] Specifically, the process for risk quantification assessment can be found in [link to relevant documentation]. Figure 4 The implementation process includes the following:

[0112] Model foundation building:

[0113] Based on the three-dimensional trajectory data of the borehole, a three-dimensional geometric model including the borehole wall, surrounding rock and hydraulic fractures is established. A high-precision finite element mesh is generated. Combining the mechanical properties of deep rock mass and engineering geological conditions, basic parameters such as rock elastic modulus, Poisson's ratio, thermal expansion coefficient and permeability tensor are input. At the same time, measured data such as geostress tensor, geothermal gradient and pore water pressure are imported as the initial boundary conditions of the model.

[0114] Construction of multi-field equations:

[0115] ①Thermal field equation:

[0116] The mathematical expression for correcting the effect of temperature perturbation on the stress field based on thermoelastic theory is as follows:

[0117] ;

[0118] In the formula: This is the stress disturbance tensor of the rock mass caused by temperature changes; The thermal expansion coefficient of the rock mass can be determined using synchronously acquired geothermal gradient data; It is the elastic modulus; The temperature change is monitored in real time by a temperature sensor. It is Poisson's ratio.

[0119] Temperature change The thermal expansion or contraction of the surrounding soil and rock mass caused by the testing device directly corrects the geostress tensor. .

[0120] ② Seepage field equation:

[0121] Combining Darcy's law and the theory of pore elasticity, the expression for the seepage field equation can be derived as follows:

[0122] ;

[0123] in, For gradient operators; The osmotic pressure coefficient tensor is obtained from the osmotic pressure decay curve after pore wall fracturing. The water pressure of the seepage water; For time; Water storage rate;

[0124] The effective stress is corrected to:

[0125] ;

[0126] In the formula: The corrected effective stress; The total stress; The pore water pressure coefficient characterizes the effect of pore water pressure on the rock and soil skeleton; This refers to the pore water pressure.

[0127] Pore ​​water pressure By reducing the stress in the rock and soil skeleton through the effective stress principle, the distribution of the stress field is affected, while the permeability coefficient is also affected. It is also subject to the constraints of the geostress tensor.

[0128] ③ Stress field equations:

[0129] The stress field equations are obtained by superimposing the elasticity equilibrium equations with multi-field coupling correction terms. The static equilibrium equations are expressed as follows:

[0130] ;

[0131] in, For gradient operators, Force per unit volume of rock mass; For geostress tensor;

[0132] The complete coupling equation is:

[0133] ;

[0134] in, This represents the initial geostress tensor; Stress disturbance caused by pore water pressure ;

[0135] At the same time, a crack propagation constraint is introduced, in the form of:

[0136] ;

[0137] In the formula: This is the calculated value of the Mohr-Coulomb yield function; Shear stress; For normal stress, It represents the cohesion of the soil and rock mass; The friction angle within the rock and soil is denoted as .

[0138] Plastic zone calculation and risk quantification:

[0139] Based on the Mohr-Coulomb yield criterion, the distribution range and depth of the plastic zone of the rock mass surrounding the borehole wall are calculated through numerical solution and iterative optimization of the coupled model. Combining the distribution of the plastic zone, the stress concentration factor and pore water pressure, a risk quantification evaluation system is established to classify the risk levels of rockburst / water inrush and the safety warning threshold, so as to realize the real-time evaluation and early warning of the stability of the surrounding rock in deep earth engineering.

[0140] The coupled model constructed in this step integrates the interaction and coupling effects of the thermal, water, and force fields, and truly reflects the multi-field coupling characteristics of ultra-deep high-pressure rock masses; the Mohr-Coulomb yield criterion is used as the basis for judging rock mass failure, making the calculation of the plastic zone of the borehole wall more scientific.

[0141] S7. Equipment Recovery and Data Processing:

[0142] This step enables the controlled depressurization of the hydraulic lock and the smooth reset of the rubber sleeve, allowing the downhole testing device to be recovered to the surface without damage, facilitating subsequent data extraction and equipment maintenance.

[0143] Specifically, after the surrounding rock risk quantification assessment is completed, the ground control calculation system 3 sends a negative pressure pulse or an ultra-high pressure shear command to the hydraulic control pipeline, triggering the one-way hydraulic lock 7 to release pressure; the rubber sleeve 6 retracts and resets by its own rebound force and the force of the internal reset spring, releasing the adhesion state with the borehole wall; finally, the downhole test device 2 is slowly retrieved to the ground through the multi-core armored cable 1, and the staff extracts the stored test data from the device, and cleans, inspects and maintains the downhole test device 2 to prepare for subsequent test operations.

[0144] Although embodiments of the present invention have been described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, and all such changes and alterations shall not depart from the protection scope of the present invention.

Claims

1. In-situ testing device for multi-field coupled thermo-hydraulic-mechanical parameters in ultra-deep high-pressure directional drilling. Its features are, include: Multi-core armored cables, downhole testing equipment, and surface control computing systems; One end of the multi-core armored cable is connected to the ground control and computing system for communication, and the other end is connected to the electrical control and communication module of the downhole testing device for electrical communication. The downhole testing device is a central tube integrated structure, which integrates an electrical control and communication module, an upper packer, a multi-functional testing module and a lower packer in sequence from top to bottom along the central tube axis. The upper packer and the lower packer are coaxially sleeved on the outside of the central tube. After setting, they form a sealed isolation section between the upper packer, the lower packer and the borehole wall for in-situ testing. The central tube has an axial water injection channel inside, and a high-pressure water injection hole connected to the water injection channel is opened on the tube wall of the central tube, and the high-pressure water injection hole is located inside the sealed isolation section. The upper and lower packers have the same structure, both including an upper piston, a lower piston, and a rubber sleeve. The rubber sleeve is sealed on the outside of the upper and lower pistons, with its two ends connected to the ends of the upper and lower pistons respectively. A sealed chamber is formed between the inner side of the rubber sleeve and the outer wall of the central tube. Each packer's upper and lower pistons are equipped with corresponding one-way hydraulic locks, and each packer is equipped with a pressure adaptive balancing valve. One end of the pressure adaptive balancing valve is connected to the water in the borehole, and the other end is connected to the sealed chamber of the rubber sleeve of the corresponding packer. It is used to introduce high-pressure water from the borehole as a balancing medium to dynamically adjust the pressure difference inside and outside the rubber sleeve. The multifunctional testing module includes an ultrasonic scanning unit, a temperature sensor, a pressure sensor, and a flow meter that are electrically connected to the electronic control and communication module.

2. An in-situ testing method for multi-field coupled parameters of thermo-hydraulic-mechanical systems in ultra-deep high-pressure directional drilling, applied to the in-situ testing device for multi-field coupled parameters of thermo-hydraulic-mechanical systems in ultra-deep high-pressure directional drilling as described in claim 1, characterized in that... Includes the following steps: S1. Lower the downhole testing device to the target formation using a multi-core armored cable; S2. The ground control and computing system controls and drives the upper and lower packers to set, forming a sealed isolation section; S3. The ground control and calculation system starts the high-pressure pump and injects water into the sealed isolation section through the water injection channel and high-pressure water injection hole to induce fracturing, and triggers the ultrasonic scanning unit to acquire the morphological data of the hole wall crack in real time; and simultaneously collects fracturing curve, geothermal gradient and pore water pressure data during the fracturing process; S4. Map the morphological data of the borehole wall cracks to the borehole coordinate system and calculate the crack deflection angle; S5. Input the fracturing curve, fracture deflection angle, geothermal gradient, and pore water pressure multi-source data into the deep learning model, combine iteratively solve the three-dimensional geostress balance equations, invert the three-dimensional geostress and permeability coefficient tensors, and complete the thermal-hydraulic-mechanical coupling correction. S6. Construct a thermo-hydraulic-mechanical coupling model, substitute the coupled and corrected three-dimensional geostress and permeability coefficient tensors into the thermo-hydraulic-mechanical coupling model, calculate the distribution of the plastic zone in the borehole wall, and quantify the rockburst / water inrush risk level based on the distribution of the plastic zone in the borehole wall. S7. Trigger the one-way hydraulic lock to release pressure. After the rubber sleeve resets, the downhole test device is retrieved to the surface via a multi-core armored cable.

3. The in-situ testing method for multi-field coupled thermo-hydraulic-mechanical parameters in ultra-deep high-pressure directional drilling as described in claim 2, characterized in that, In step S1, during the process of lowering the downhole testing device using a multi-core armored cable, the position of the downhole testing device is dynamically calibrated based on the three-dimensional trajectory data of the borehole, achieving millimeter-level positioning of the target layer.

4. The in-situ testing method for multi-field coupled thermo-hydraulic-mechanical parameters in ultra-deep high-pressure directional drilling as described in claim 2, characterized in that, Step S2 also includes: introducing high-pressure water from inside the hole into the sealed chamber of the rubber tube in real time through a pressure adaptive balancing valve, and dynamically adjusting the pressure difference inside and outside the rubber tube.

5. The in-situ testing method for multi-field coupled thermo-hydraulic-mechanical parameters in ultra-deep high-pressure directional drilling as described in claim 2, characterized in that, In step S3, the morphological data of the hole wall cracks includes the geometric contour and spatial distribution data of the hole wall cracks. In step S4, the geometric contour and spatial distribution data of the borehole wall cracks obtained by ultrasonic scanning are mapped to the borehole coordinate system, and the deflection angle of the cracks relative to the borehole axis is calculated, based on the three-dimensional trajectory information of the borehole.

6. The in-situ testing method for multi-field coupled thermo-hydraulic-mechanical parameters in ultra-deep high-pressure directional drilling as described in claim 5, characterized in that, In step S5, the fracturing curve, fracture deflection angle, geothermal gradient, and pore water pressure multi-source data are input into the deep learning model. Combined with iterative solutions to the three-dimensional geostress equilibrium equations, the three-dimensional geostress and permeability coefficient tensors are obtained through inversion. The process of completing the thermal-hydraulic-mechanical coupling correction includes: The fracturing curve features, fracture deflection angle, borehole trajectory parameters, regional geological structure data, geothermal gradient, and pore water pressure data are input into a deep learning model pre-trained on a historical fracturing test dataset. Regional geological statistics are used as the initial iteration values ​​of geostress. The deep learning model is then used to calculate and output the initial solution of the geostress tensor. The initial solution is substituted into the three-dimensional geostress equilibrium equations and iteratively solved to obtain the three-dimensional geostress tensor. The permeability coefficient tensor is then obtained by combining the permeability pressure decay curve. Finally, based on geothermal gradient and pore water pressure data, the calculated three-dimensional geostress tensor and permeability coefficient tensor are corrected by thermal-hydraulic-mechanical coupling.

7. The in-situ testing method for multi-field coupled thermo-hydraulic-mechanical parameters in ultra-deep high-pressure directional drilling as described in claim 6, characterized in that, The process of substituting the initial solution of the geostress tensor into the three-dimensional geostress equilibrium equations for iterative solution includes: Based on the initial solution of the geostress tensor, the residuals between the theoretical fracturing pressure and the actual fracturing pressure, and the deviation between the theoretical fracture deflection angle and the measured value are calculated. The model solution weights are adjusted according to the residuals and deviations through the backpropagation mechanism of the deep learning model, and the iterative value of the geostress tensor is updated. The updated iterative value is substituted back into the three-dimensional geostress equilibrium equations until the residuals and deviations meet the convergence conditions, and the calculated three-dimensional geostress tensor is output.

8. The in-situ testing method for multi-field coupled thermo-hydraulic-mechanical parameters in ultra-deep high-pressure directional drilling as described in claim 7, characterized in that, The convergence condition of the residual is the fracturing pressure residual. The convergence condition for the deviation is the crack deflection angle deviation. .

9. The in-situ testing method for multi-field coupled thermo-hydraulic-mechanical parameters in ultra-deep high-pressure directional drilling as described in claim 2, characterized in that, In step S6, the constructed thermal-hydraulic-mechanical coupling model is as follows: ； in, This represents the coupled geostress tensor. This represents the initial geostress tensor; This represents the stress disturbance tensor caused by temperature changes in the rock mass. ; in, The coefficient of thermal expansion of the rock mass; It is the elastic modulus; This refers to the change in temperature. Poisson's ratio; This is the stress disturbance tensor caused by pore water pressure. ; in, Pore ​​water pressure; The pore water pressure coefficient characterizes the effect of pore water pressure on the rock and soil skeleton.

10. The in-situ testing method for multi-field coupled thermo-hydraulic-mechanical parameters in ultra-deep high-pressure directional drilling as described in claim 9, characterized in that, Step S6, the process of calculating the distribution of the plastic zone on the hole wall includes: Based on the Mohr-Coulomb yield criterion, the distribution range and depth of the plastic zone of the rock mass around the borehole wall are calculated by substituting the coupled and corrected three-dimensional geostress and permeability coefficient tensors. The Mohr-Coulomb yield criterion is characterized by a crack propagation constraint, and its expression is as follows: ； This is the calculated value of the Mohr-Coulomb yield function; Shear stress; Normal stress; It represents the cohesion of the soil and rock mass; The friction angle within the rock and soil is denoted as .

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