Dynamic deflecting trajectory regulation and control method and system based on real-time crustal stress inversion

Abstract

The invention relates to the field of drilling, and provides a dynamic deflecting trajectory regulation and control method and system based on real-time crustal stress inversion in order to improve the safety of drilling operation, the dynamic adjustment of the pushing orientation and the deflecting angle of a drill bit is guided by obtaining the crustal stress main stress, it is ensured that the drilling trajectory is propelled along the most favorable stress path, and the drilling efficiency is improved. The safety and track precision of ultra-deep hole drilling are fundamentally improved, deflecting energy consumption is reduced, and high-quality hole conditions are provided for follow-up hole completion and fracturing operation.

Description

Technical Field

[0001] This invention relates to the field of drilling, specifically to a method and system for controlling dynamic directional drilling trajectory based on real-time geostress inversion. Background Technology

[0002] In the fields of deep-earth energy development and ultra-deep borehole exploration, with the continuous advancement of development and exploration operations, the required drilling depth is constantly increasing, gradually extending to depths of 5,000 meters and even 10,000 meters. Within this depth range, the geological environment exhibits significant extreme characteristics, specifically the coupling of high ground stress differences and complex structural stresses, forming a complex ground stress environment that poses severe challenges to the safe and efficient conduct of drilling operations.

[0003] After the drill bit completes the rock-breaking and borehole-forming operation, the original triaxial principal stress equilibrium state of the formation is disrupted and redistributed, resulting in significant differences in the mechanical response of the borehole wall in different orientations. Specifically, in the direction of the minimum horizontal principal stress, shear collapse zones are easily formed on the borehole wall, which poses a serious threat to the stability of the borehole.

[0004] Currently widely used rotary steerable drilling tools primarily rely on inertial navigation technology and attitude error closed-loop control mechanisms for trajectory correction. Their core control strategy revolves around geometric deviations, failing to consider the matching relationship between drilling azimuth and geostress direction. When there is a deviation between the drilling direction and the principal stress direction, the drilling tool's pushing action is often in an unfavorable orientation. This situation can lead to localized stress concentration in the borehole wall, resulting in a significant decrease in borehole stability. This problem is particularly pronounced in areas with high stress differences, easily inducing borehole instability and even borehole wall collapse, severely impacting the progress and safety of drilling operations. Summary of the Invention

[0005] To improve the safety of drilling operations, this invention provides a method and system for dynamic directional drilling trajectory control based on real-time geostress inversion.

[0006] The technical solution adopted by the present invention to solve the above problems is:

[0007] A dynamic tilting trajectory control method based on real-time geostress inversion includes:

[0008] Step 1: Initial drilling based on the preset trajectory curve;

[0009] Step 2: Obtain the direction of maximum horizontal principal stress during drilling stop and loading. After drilling resumes, the drill bit moves forward along its original trajectory;

[0010] Step 3: When the current drill bit advance azimuth angle is different from the direction of maximum horizontal principal stress... When the included angle deviation exceeds the set threshold, attitude adjustment is performed: under the condition that it does not conflict with the drilling trajectory, the drill bit advance direction is adjusted, with the advance direction aiming at the most favorable drilling path that approaches the direction of minimum horizontal principal stress.

[0011] Furthermore, in step 2, microseismic signals are acquired during drilling cessation and loading, and focal mechanism inversion is performed to determine the direction of the maximum horizontal principal stress. .

[0012] Furthermore, in step 2, the step of obtaining the direction of the maximum horizontal principal stress is as follows:

[0013] Once the drill bit has drilled to the length of a drill pipe, it stops rotating, and the drilling fluid circulation is suspended.

[0014] Microseismic signals are acquired, and the focal mechanism solution is obtained from the acquired microseismic signals. The current geostress tensor is then obtained by inversion based on the focal mechanism solution, and the direction of the maximum horizontal principal stress is determined based on the geostress tensor. .

[0015] Furthermore, step 2 also includes: after resuming drilling, periodically scanning the wellbore based on ultrasonic imaging to identify the location of the maximum collapse distribution, and taking its orthogonal direction as the direction of the maximum horizontal principal stress. ;like and If the error is within the allowable range, proceed to step 3; otherwise, select another cluster of microseismic signals to determine the direction of the maximum horizontal principal stress. .

[0016] Furthermore, for the borehole wall section where the surface has collapsed, the distance from the borehole wall to the sensor is calculated by obtaining the propagation time of the ultrasonic wave from emission to reflection from the borehole wall to reception, combined with the wave velocity in the mud, and the actual contour of the collapsed borehole wall at that depth is reconstructed by fusing the ranging data from all directions.

[0017] For borehole sections where no surface collapse has occurred, the spatial location and damage extent of hidden fractures can be determined by capturing the abnormal weakening of the first wave reflection amplitude and combining it with the hysteresis echo in the full wave train analysis.

[0018] The maximum distribution direction of the collapse is determined based on the actual contour of the collapse hole wall or the spatial location and degree of damage of the hidden cracks.

[0019] Furthermore, if and If the error is outside the allowable error range, an alarm message will also be displayed.

[0020] Furthermore, the threshold is set to 20°.

[0021] Furthermore, after each round of drill pipe advance is completed, steps 2 and 3 are repeated.

[0022] A dynamic tilting trajectory control system based on real-time geostress inversion is used to implement a dynamic tilting trajectory control method based on real-time geostress inversion, including:

[0023] Microseismic signal monitoring module: used to acquire microseismic signals;

[0024] Data processing module: Obtains the focal mechanism solution from the acquired microseismic signals, inverts the current geostress tensor based on the focal mechanism solution, and determines the direction of the maximum horizontal principal stress based on the geostress tensor. ;

[0025] Attitude adjustment module: When the current drill bit advance azimuth angle is relative to the direction of maximum horizontal principal stress... When the included angle deviation exceeds the set threshold, attitude adjustment is performed: under the condition that it does not conflict with the drilling trajectory, the drill bit advance direction is adjusted, with the advance direction aiming at the most favorable drilling path that approaches the direction of minimum horizontal principal stress.

[0026] Furthermore, it also includes an ultrasonic imaging module: for periodic scanning of the wellbore;

[0027] The data processing module also includes: determining the direction of the maximum horizontal principal stress based on the scanning results from the ultrasound imaging module. ;like and If the error is outside the allowable error range, another cluster of microseismic signals should be selected to determine the direction of the maximum horizontal principal stress. .

[0028] The advantages of this invention compared to the prior art are: by obtaining the principal stress of the ground stress to guide the dynamic adjustment of the drill bit's pushing azimuth and directional angle, it ensures that the drilling trajectory advances along the most favorable stress path, fundamentally improving the equipment safety and hole quality of ultra-deep hole drilling, and providing high-quality hole conditions for subsequent hole completion and fracturing operations. Attached Figure Description

[0029] Figure 1 The flowchart shows the dynamic tilting trajectory control method based on real-time geostress inversion.

[0030] Figure 2 This is a schematic diagram of the surface spalling area and the hidden crack area;

[0031] Figure 3 This is a schematic diagram of the echo.

[0032] Figure 4 This is a schematic diagram showing the location of the borehole collapse. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] Existing technologies for rotary steerable drilling typically focus solely on geometric trajectory deviation as the core control objective. For example, when vertical boreholes need to avoid unfavorable structures such as aquifers, the drill bit can arbitrarily choose its thrust orientation in the horizontal direction to bypass the obstacle and continue drilling deeper. However, this method does not consider the matching relationship between the drilling orientation and the direction of ground stress. In practical engineering, however, borehole stability is significantly affected by the distribution of ground stress. If the thrust orientation is in an unfavorable direction of ground stress, it can easily cause localized stress concentration in the borehole wall, leading to decreased stability. This problem is particularly prominent in formations with high stress differentials, easily inducing borehole instability or even collapse. To address these issues, this invention proposes a dynamic directional drilling trajectory control method and system based on real-time ground stress inversion.

[0035] like Figure 1 As shown, the dynamic tilting trajectory control method based on real-time geostress inversion includes:

[0036] Step 1: Initially drill according to the preset trajectory curve.

[0037] Before drilling operations begin, the direction of the maximum horizontal principal stress in the area is calculated based on surface geological data. The initial pushing sector of the directional drilling tool is set, causing the drill bit to advance in a predetermined direction during the initial stage of drilling. The drilling trajectory in this stage is mainly executed according to the preset trajectory curve.

[0038] Step 2: Obtain the direction of maximum horizontal principal stress during drilling stop and loading. After drilling resumes, the drill bit moves along its original trajectory.

[0039] Traditional geostress monitoring technologies, such as optical and resistivity imaging, have poor reliability in turbid downhole environments, making it difficult to continuously monitor borehole wall fracture morphology and stress orientation, and thus unable to provide real-time and accurate geostress data support for drill bit azimuth adjustment.

[0040] Based on this, this embodiment uses a microseismic monitoring system to capture surrounding rock fracture signals and performs focal mechanism inversion to extract principal stress directions. Specifically:

[0041] Once drilling reaches the length of one drill pipe, the system automatically enters the stop-drilling and loading process. At this point, the drill bit stops rotating, drilling fluid circulation is paused, and a low-noise environment is created. The microseismic monitoring system acquires microseismic signals excited by downhole micro-fracture events within this window. Based on the acquired microseismic signals, a spatial distribution model of the microseismic events is constructed. The focal mechanism solution is determined based on the spatial distribution model. The first geostress tensor of the fault plane is solved based on the focal mechanism solution. The second geostress tensor is determined by linear inversion of the P / T axis with respect to geostress based on the azimuth and dip angles of the first geostress tensor. The principal stresses in each direction of the fault plane are determined based on the shape ratio of the second geostress tensor. The method for determining the principal stresses based on microseismic signals is existing technology and will not be elaborated upon here.

[0042] To improve the accuracy of the direction of the maximum horizontal principal stress, this implementation also introduces an auxiliary judgment method based on ultrasonic imaging, specifically:

[0043] After the drill pipe is loaded, the system restarts the drilling operation, and the drill bit continues to advance along the original trajectory. The ultrasonic imaging system periodically scans the well wall to acquire information on the well wall fracture morphology, the width of the collapse zone, and its spatial orientation. During this process, the microseismic monitoring system stops acquiring data to avoid interference from drilling vibrations on the identification of microseismic signals, while preparing for the next round of data acquisition during the drilling stop.

[0044] Compared to traditional optical borehole television, the fundamental advantage of in-hole ultrasonic imaging lies in its ability to effectively penetrate turbid media. Therefore, this technology can achieve in-situ borehole wall imaging under normal drilling conditions with mud circulation, eliminating the need for additional borehole cleaning procedures.

[0045] For borehole wall sections where surface collapse has occurred, borehole ultrasonic television measurements are performed using an array of ultrasonic transducers arranged around the drill pipe to obtain the propagation time Δt of the ultrasonic wave from emission to reflection from the borehole wall to reception, combined with the wave velocity in the drilling mud. The distance s from the hole wall to the sensor can then be calculated. Ultimately, by fusing distance measurement data from all directions, the actual contour of the collapse hole wall at that depth can be reconstructed.

[0046] For drilled sections that have not experienced surface spalling, internal cracks may exist, such as... Figure 2 As shown, borehole television can identify and analyze hidden cracks behind the borehole wall by combining the received reflected waveform amplitude.

[0047] For a longitudinal ultrasonic wave perpendicular to the surface of an entrance hole, let u(x,t) be the displacement function of a particle at time t. Then the displacement functions of the incident wave, reflected wave, and transmitted wave are respectively expressed as:

[0048] Incident wave: ,

[0049] Reflected wave: ,

[0050] Transmitted waves: ,

[0051] in, , , These represent the displacement amplitudes of the incident wave, reflected wave, and transmitted wave, respectively. Angular frequency; , , , represent the wave number in the fluid and rock media, respectively; x represents the displacement in the wave propagation direction; and j represents the imaginary number.

[0052] The stress and displacement boundary conditions at the hole wall interface (x=0) are: stress continuity: Displacement continuity: , These represent the stresses at the interface of the incident wave, reflected wave, and transmitted wave, respectively.

[0053] Based on displacement function combined with constitutive equation Substituting the boundary conditions and solving the simultaneous equations, we can obtain the analytical expression for the displacement reflection coefficient R under the condition of perpendicular incidence: In the formula , These are the wave impedances of the drilling mud and the borehole wall rock, respectively. , For mud density, For the density of the rock mass, The velocity of ultrasonic waves in the rock mass is denoted as .

[0054] According to the above derivation formula, the reflection coefficient can be calculated from the amplitude of the reflected wave. The strength is directly affected by the rock mass wave impedance. The impact, and It is a key physical quantity for measuring the quality of rock mass. For intact rock mass, which is dense and has a high sound velocity, its wave impedance is... Much greater than fluid wave impedance The reflected echo signal is extremely strong, appearing as a bright feature in the acoustic television image; for areas with hidden cracks, although the surface of the borehole wall has not collapsed, the rock mass behind the borehole wall has a high density due to the development of internal fissures. With equivalent wave velocity Sudden decrease, wave impedance Consequently, the amplitude of the reflected echo decreases. A significant decrease was observed.

[0055] This invention captures the anomalous attenuation of the initial reflection amplitude and, in conjunction with the hysteresis echo in full-wave train analysis—that is, the secondary reflection of the transmitted wave at the surface of the internal fracture—such as... Figure 3 As shown, it can realize the spatial location and quantitative evaluation of the damage degree of hidden cracks behind the borehole wall.

[0056] The maximum distribution direction of the collapse was identified by combining the scanning results, that is, the orientation of the borehole wall corresponding to the maximum collapse depth and the damage depth, such as... Figure 2 As shown, the direction of the principal stress axis is determined using the wellbore circumferential stress formula in elasticity:

[0057] ,

[0058] in, For the circumferential stress of the well wall, and These are the maximum and minimum horizontal principal stresses, respectively. Pore ​​pressure, The pressure difference between the well fluid and the formation. This is a thermal stress correction term. Differentiating this formula reveals the location of the maximum circumferential stress value. and This is the direction of the minimum horizontal principal stress. At this location, the borehole wall undergoes compressive-shear failure under stress concentration, thus forming a collapse zone. The direction of maximum collapse distribution corresponds to the direction of the minimum horizontal principal stress. Its orthogonal direction is The location and distribution of borehole collapses are as follows: Figure 4 As shown.

[0059] When the microseismic inversion occurs in the second step and If the direction identification is valid within the allowable error range, the geostress direction obtained from the microseismic inversion is recorded; otherwise, another cluster of microseismic signals is selected for source moment tensor inversion to determine the final geostress direction.

[0060] The microseismic monitoring system is mainly used to capture surrounding rock fracturing signals and perform source mechanism inversion during drilling shutdowns to extract the direction of in-situ stress. The ultrasonic imaging system dynamically monitors the geometry of wellbore collapse during drilling, assisting in determining the spatial projection orientation of the stress direction. The fusion of these two sensing mechanisms provides a real, dynamic, and continuous in-situ stress field input for optimizing the build-up trajectory, and provides more accurate and faster-responding geological guidance for ultra-deep hole drilling operations.

[0061] Step 3, Attitude Adjustment: On the one hand, when the drill bit's pushing direction is parallel to the direction of the minimum horizontal principal stress, the broken hole wall, which was originally in a stress concentration zone but had not yet experienced surface collapse, is highly likely to collapse under the squeezing action of the pushing mechanism. Areas that have already experienced collapse may then experience secondary collapse, further reducing the hole quality. On the other hand, when the drill bit's drilling direction is parallel to the minimum horizontal principal stress, the stress concentration phenomenon on the hole wall will be significantly stronger than when the drilling direction is parallel to the maximum horizontal principal stress, thus drastically increasing the risk of hole wall collapse. Therefore, when the drill bit's pushing direction angle is parallel to the direction of the maximum horizontal principal stress... When the included angle deviation exceeds the set threshold (e.g., 20°), attitude adjustment is required: under the condition that it does not conflict with the drilling trajectory, adjust the drill bit advance direction to make it aim at the most favorable drilling path that approaches the direction of minimum horizontal principal stress, and adjust the push angle and thrust level of the guide mechanism accordingly to achieve synchronous tuning of the drilling direction and principal stress field, thereby minimizing the risk of wellbore fracture.

[0062] After each round of drill pipe advance, the system automatically returns to the second step to re-perform microseismic acquisition, ultrasonic verification, and trajectory determination, forming a complete dynamic closed-loop control process. All inversion results, stress parameters, and attitude adjustment commands are synchronously uploaded to the ground control console via a high-speed data link, assisting geological guidance engineers in real-time judgment of drilling status and enabling manual intervention, thereby improving the overall system's stability and adaptability.

[0063] Correspondingly, the present invention also provides a dynamic tilting trajectory control system based on real-time geostress inversion, used to realize a dynamic tilting trajectory control method based on real-time geostress inversion, including:

[0064] Microseismic signal monitoring module: used to acquire microseismic signals;

[0065] Data processing module: Obtains the focal mechanism solution from the acquired microseismic signals, inverts the current geostress tensor based on the focal mechanism solution, and determines the direction of the maximum horizontal principal stress based on the geostress tensor. ;

[0066] Attitude adjustment module: When the current drill bit advance azimuth angle is relative to the direction of maximum horizontal principal stress... When the included angle deviation exceeds a set threshold, attitude adjustment is performed: under the condition that it does not conflict with the drilling trajectory, the drill bit advance direction is adjusted, with the advance direction aiming at the most favorable drilling path that approaches the direction of minimum horizontal principal stress.

[0067] Furthermore, it also includes an ultrasonic imaging module: for periodic scanning of the wellbore;

[0068] The data processing module also includes: determining the direction of the maximum horizontal principal stress based on the scanning results from the ultrasound imaging module. ;like and If the error is outside the allowable error range, another cluster of microseismic signals should be selected to determine the direction of the maximum horizontal principal stress. .

Claims

1. A dynamic tilting trajectory control method based on real-time geostress inversion, characterized in that, include: Step 1: Initial drilling based on the preset trajectory curve; Step 2: Obtain the direction of maximum horizontal principal stress during drilling stop and loading. After drilling resumes, the drill bit moves forward along its original trajectory; Step 3: When the current drill bit advance azimuth angle is different from the direction of maximum horizontal principal stress... When the included angle deviation exceeds the set threshold, attitude adjustment is performed: under the condition that it does not conflict with the drilling trajectory, the drill bit advance direction is adjusted, with the advance direction aiming at the most favorable drilling path that approaches the direction of minimum horizontal principal stress.

2. The dynamic tilting trajectory control method based on real-time geostress inversion according to claim 1, characterized in that, Step 2 involves acquiring microseismic signals during drilling cessation and loading, and performing source mechanism inversion to determine the direction of the maximum horizontal principal stress. .

3. The dynamic tilting trajectory control method based on real-time geostress inversion according to claim 2, characterized in that, In step 2, the steps for obtaining the direction of the maximum horizontal principal stress are as follows: Once the drill bit has drilled to the length of a drill pipe, it stops rotating, and the drilling fluid circulation is suspended. Microseismic signals are acquired, and the focal mechanism solution is obtained from the acquired microseismic signals. The current geostress tensor is then obtained by inversion based on the focal mechanism solution, and the direction of the maximum horizontal principal stress is determined based on the geostress tensor. .

4. The dynamic tilting trajectory control method based on real-time geostress inversion according to claim 3, characterized in that, Step 2 also includes: after resuming drilling, periodically scanning the wellbore using ultrasonic imaging to identify the location of the maximum collapse distribution, and taking its orthogonal direction as the direction of the maximum horizontal principal stress. ;like and If the error is within the allowable range, proceed to step 3; otherwise, select another cluster of microseismic signals to determine the direction of the maximum horizontal principal stress. .

5. The dynamic tilting trajectory control method based on real-time geostress inversion according to claim 4, characterized in that, For the borehole wall section where the surface has collapsed, the distance from the borehole wall to the sensor is calculated by obtaining the propagation time of the ultrasonic wave from emission to reflection and reception, combined with the wave velocity in the mud, and the actual contour of the collapsed borehole wall at that depth is reconstructed by fusing the ranging data from all directions. For borehole sections where no surface collapse has occurred, the spatial location and damage extent of hidden fractures can be determined by capturing the abnormal weakening of the first wave reflection amplitude and combining it with the hysteresis echo in the full wave train analysis. The maximum distribution direction of the collapse is determined based on the actual contour of the collapse hole wall or the spatial location and degree of damage of the hidden cracks.

6. The dynamic tilting trajectory control method based on real-time geostress inversion according to claim 4, characterized in that, like and If the error is outside the allowable error range, an alarm message will also be displayed.

7. The dynamic tilting trajectory control method based on real-time geostress inversion according to claim 1, characterized in that, Set the threshold to .

8. The dynamic tilting trajectory control method based on real-time geostress inversion according to claim 1, characterized in that, After each round of drill pipe advance is completed, repeat steps 2 and 3.

9. A dynamic tilting trajectory control system based on real-time geostress inversion, used to implement the dynamic tilting trajectory control method based on real-time geostress inversion as described in any one of claims 1-8, characterized in that, include: Microseismic signal monitoring module: used to acquire microseismic signals; Data processing module: Obtains the focal mechanism solution from the acquired microseismic signals, inverts the current geostress tensor based on the focal mechanism solution, and determines the direction of the maximum horizontal principal stress based on the geostress tensor. ; Attitude adjustment module: When the current drill bit advance azimuth angle is relative to the direction of maximum horizontal principal stress... When the included angle deviation exceeds the set threshold, attitude adjustment is performed: under the condition that it does not conflict with the drilling trajectory, the drill bit advance direction is adjusted, with the advance direction aiming at the most favorable drilling path that approaches the direction of minimum horizontal principal stress.

10. The dynamic tilting trajectory control system based on real-time geostress inversion according to claim 9, characterized in that, It also includes an ultrasonic imaging module: which performs periodic scanning of the well wall; The data processing module also includes: determining the direction of the maximum horizontal principal stress based on the scanning results from the ultrasound imaging module. ;like and If the error is outside the allowable error range, another cluster of microseismic signals should be selected to determine the direction of the maximum horizontal principal stress. .

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