143 results about "Fracture pressure" patented technology

The invention provides a hydraulic fracturing fracture net distribution form near-field monitoring method, which comprises the following steps of: arranging a plurality of roof monitoring holes in roadways on two sides of an underground coal mine working surface, installing electromagnetic signal sensors in each roof monitoring hole and on anchor rods of roadway stoping sides, and constructing a full-space monitoring network covering a hydraulic fracturing layer; a data interpretation processing module of the electromagnetic signal time-shifting imaging analysis system comprises a multi-field coupling mathematical model for analyzing and deducing real-time imaging of electromagnetic signals; in the hydraulic fracturing process, an electromagnetic signal sensor is used for monitoring a current field, an electromagnetic field and an ion diffusion field in the rock mass fracture development and expansion process, a monitoring result is substituted into an electromagnetic signal time-shifting imaging analysis system for calculation and feature value extraction, and the fracture net distribution form is deduced through the feature value. According to the invention, the expansion path of the fracturing fluid in the rock stratum can be monitored in real time, the three-dimensional distribution form of the hydraulic fracturing fracture network can be inverted, and a new technical support is provided for the inspection of the hydraulic fracturing pressure relief effect of the underground coal mine.

The invention provides a hydraulic fracturing crack propagation simulation method and device and electronic equipment, and the method comprises the steps: obtaining the ground stress field distribution of each fracturing section through a geomechanical model according to the geological parameters, logging interpretation and rock mechanics experiment data of a target area fracturing section; utilizing an induced stress field model to simulate induced stress distribution of each fracturing section; obtaining comprehensive crustal stress field distribution according to the crustal stress field distribution and the induced stress distribution; the theoretical crack initiation pressure of each perforation cluster of each fracturing section is calculated according to the comprehensive crustal stress field distribution by means of a perforation cluster crack pressure model, perforation cluster crack initiation data of each fracturing section are determined according to the theoretical crack initiation pressure and the actual crack pressure, and the perforation cluster crack initiation data comprise the perforation cluster crack initiation state and the perforation cluster crack initiation number; and utilizing the multi-cluster crack propagation model to obtain a crack propagation trajectory simulation result according to perforation cluster crack initiation data and an actual pump injection program. According to the method and the device, hydraulic fracture expansion of segmented multi-cluster fracturing can be accurately simulated.

The invention discloses a proppant distribution optimization method based on pressure distribution control. The method comprises the following steps: constructing an in-crack pressure distribution model considering a multi-physics field coupling effect; according to the fracture pressure distribution model, in combination with a geostatistics method, performing fracture region division on the fracture, and for each fracture region, calculating a corresponding pressure gradient value by using an optimization algorithm; based on the pressure gradient values corresponding to all the areas of the crack, the injection process of the proppant is controlled; in the injection process of the proppant, pressure data in the crack are monitored in real time, and when it is monitored that the pressure data in the crack exceed a preset pressure threshold value, the injection pressure of the proppant is adjusted in real time. According to the method, through accurate fracture pressure distribution analysis, a scientific pressure gradient adjustment strategy and real-time injection process adjustment, uniform and efficient distribution of the proppant in the fracture is achieved.

The invention belongs to the technical field of coal mine safety mining, and relates to a microwave-hydraulic power combined permeability-increasing pressure relief and gas extraction method, which comprises the following steps of: firstly, carrying out geological survey and coal sample test to obtain physical and mechanical parameters of a coal seam; calculating the fracture pressure of the coal seam according to the parameters and determining hydraulic fracturing and microwave irradiation parameters; a hydraulic fracturing drill hole and a microwave irradiation drill hole are constructed; fracturing, irradiation and monitoring equipment is installed; performing low-frequency microwave preheating on the coal seam, and then performing staged hydraulic fracturing; the fracturing effect is evaluated through micro-seismic monitoring, and a weak area is marked; and finally, high-frequency microwave enhanced irradiation is carried out in the weak area, and meanwhile gas extraction is carried out. According to the method, through the synergistic effect of microwave thermal cracking and hydraulic fracturing, the coal seam permeability and the gas desorption efficiency are remarkably improved, meanwhile, the rock burst risk is reduced, safe and efficient gas extraction is achieved, and a reliable technical scheme is provided for high-gas coal seam mining.

The invention discloses a fracture pressure prediction and internal friction angle joint inversion method for a heterogeneous stratum. The invention belongs to the technical field of petroleum engineering and artificial intelligence cross application, well depth is used as an independent variable, the minimum / maximum horizontal stress, pore pressure and cohesion are combined to construct well depth mixed input, only multi-scale periodic basis function transformation is carried out on the well depth, and a linear well depth channel is reserved; establishing a rupture pressure depth mapping model, introducing an augmented Lagrange physical constraint containing dual variables and a dynamic threshold, adaptively adjusting a physical weight according to a physical residual error and a threshold difference value, realizing dynamic balance of a rupture criterion and data fitting, and searching and optimizing a model topology by using a multi-target network structure; under a limited sample, a fracture pressure profile and a physically reasonable internal friction angle can be obtained at the same time, and the prediction precision and the physical consistency are improved.

The invention relates to a method for treating shale oil crack wall surfaces by using carbon nanotubes to increase the heat transfer capacity of a reservoir, a plurality of horizontal wells are drilled from the ground, the horizontal sections of the horizontal wells form three parallel well rows, the uppermost well row and the lowermost well row are heating wells, and the middle well row is a production well. The fracturing fluid carrying the proppant is injected into the heating well and the production well with the displacement greatly exceeding the stratum absorption capacity, the bottom hole pressure is larger than the stratum fracture pressure, hydraulic fracturing is carried out, a tensional fracture area and a communication well group are generated, and meanwhile it is guaranteed that fractures are not closed after the proppant is filled. Under the condition that the pressure is lower than the formation fracture pressure, a weak acid solution is slowly squeezed into the heating well and the production well, the well wall and the crack wall face are treated, and a large number of corrosion micropores are formed. And under the condition that the pressure is lower than the stratum fracture pressure, a weak acid solution added with the carbon nano tubes is squeezed into the heating well and the production well, so that the carbon nano tubes are adsorbed or filled in the corrosion micropores, and the micropores where the carbon nano tubes are attached are formed. And high-temperature steam is circularly introduced into the heating well and the production well to heat the oil shale stratum. After heating for a certain time, stopping steam injection of the production well, and changing into production; and continuously injecting steam into the heating well. The method is suitable for an oil shale underground in-situ conversion exploitation technology, and is also suitable for geothermal exploitation and heavy oil thermal exploitation.

The invention discloses a ground vertical shaft and underground horizontal well combined well spacing method which comprises the following steps: determining vertical shaft estimated fracturing information and horizontal well estimated fracturing information according to acquired fracturing construction information of surrounding mines; the width of the to-be-mined working face and the lateral mining-induced fracture range of the mined working face are obtained, vertical shaft construction information is determined according to the width of the to-be-mined working face, the lateral mining-induced fracture range and the vertical shaft estimated fracturing information, fracturing construction is conducted on the thick and hard roof based on the vertical shaft construction information, and the vertical shaft fracturing range is obtained; horizontal well construction information is determined according to the horizontal well estimated fracturing information and the vertical well fracturing range, and fracturing construction is conducted on the impact main control rock stratum based on the horizontal well construction information; the plurality of ground vertical shafts are divided into at least two vertical shaft groups which are arranged at intervals along the inclined direction of a to-be-mined working face; according to the combined well spacing method provided by the embodiment of the invention, all-directional fracturing pressure relief can be carried out on the thick and hard top plate of the super-long working face, and cooperative prevention and control on rock burst and mine earthquake disasters are realized.

The invention discloses a method for predicting a stratum drilling fluid easy-to-leak position by using logging data, which relates to the field of petroleum and natural gas exploration and development, and is characterized in that the stratum drilling fluid easy-to-leak position is predicted through five or more sample adjacent well target stratum rock mineral components, lithology, fracture and pore morphological characteristics and rock mechanics experimental tests; the rock tensile strength performance, the stratum leakage channel and the reservoir space characteristics of the target stratum are revealed, and rock mechanical parameters and ground stress are obtained; on the basis of fine division of small layers of a target stratum, performing thinning or interpolation processing on rock mechanical parameters, ground stress and stratum pressure data of a sample adjacent well, and determining a prediction weight according to a distance between the adjacent well and a prediction well to realize prediction calculation of target stratum data of the prediction well; and calculating and predicting collapse pressure, leakage pressure and fracture pressure of the target stratum of the well, and correcting the collapse pressure, the leakage pressure and the fracture pressure according to the mode so as to predict the stratum drilling fluid leakage-prone position before drilling. According to the method, the drilling fluid easy-to-leak position can be subjected to pre-drilling fine prediction, and quality-improving and efficiency-improving drilling of the complex easy-to-leak stratum is achieved.

The invention relates to a pressure-controlled drilling formation pressure calculation and control method and system based on multi-field coupling, and belongs to the field of oil exploration and development. The method comprises the steps that 1, an industrial personal computer is connected with a logging instrument, and basic data needed by calculation are obtained in real time; 2, shaft-stratum space domain grids are divided, and drill rod and annulus temperature distribution and stratum temperature distribution at different distances from a borehole are calculated; 3, considering the thermal-fluid-solid multi-field coupling influence, and calculating well circumference stresses at different well depth positions in elastic-plastic regions; 4, solving a real-time formation pore pressure profile after multi-factor coupling correction; 5, calculating real-time stratum fracture pressure profiles and collapse pressure profiles at the well walls at the different well depth positions after multi-factor coupling correction in the elastic-plastic areas; and 6, determining a bottom hole pressure control standard, calculating in real time based on a shaft hydraulic parameter calculation model, and controlling the wellhead back pressure in real time through an industrial personal computer. The method can effectively improve the calculation precision of the formation pressure during the pressure-controlled drilling period.

The invention discloses a non-isothermal three-dimensional fractured core acidification numerical simulation method which comprises the following steps: S1, constructing a fractured core acidification numerical simulation physical model, dividing grids and endowing physical parameters; s2, calculating a fluid channeling coefficient; s3, solving a matrix and fracture pressure control equation, calculating seepage velocity and molar reaction heat, and recording current injection pressure; s4, solving a temperature control equation of the matrix, the fracture acid liquor and the rock, and calculating an effective diffusion coefficient, an acid liquor reaction rate constant and a mass transfer coefficient of the acid liquor; s5, solving a matrix and fracture acid liquor concentration control equation, and calculating the porosity, the pore throat radius, the permeability and the pore specific surface area of the current time step; and S6, judging whether the wormhole breaks through the rock core or not according to the injection pressure of the current time step, and obtaining a three-dimensional fractured rock core acidification numerical simulation result. According to the method, the three-dimensional fracture network and the non-isothermal field are deeply coupled, so that the precision of three-dimensional fractured core acidification numerical simulation is effectively improved.

The invention discloses a hydraulic fracturing pressure relief method based on fracturing parameter adaptive adjustment, and relates to the technical field of oil and gas exploitation engineering, and the method comprises the following steps: carrying out multi-scale crustal stress profile modeling on a target stratum before fracturing, obtaining stress difference distribution between the target stratum and an adjacent stratum, and establishing a fracture propagation risk prediction model; in the fracturing process, real-time stratum response parameters are synchronously collected through the distributed optical fiber sensor and the microseism monitoring device. By constructing a real-time sensing and simulation closed-loop system, the response speed and parameter regulation and control accuracy in the fracturing process are improved; a multi-point pressure relief and path prediction mechanism is adopted, and intelligent guidance and anomaly correction of the crack trend are achieved; and under the complex geological condition, the integrity of the reservoir is guaranteed, the fracturing efficiency and the resource recovery efficiency are improved, non-target horizon damage and energy waste are avoided, and remarkable engineering application value and economic benefits are achieved.

The invention provides a rock mechanics dynamic analysis method, system and equipment based on numerical simulation, and relates to the technical field of rock mechanics analys.The method comprises the steps that a three-dimensional geologic model and a three-dimensional geomechanical attribute model of a target sequestration body are constructed; based on the three-dimensional geologic model, establishing an oil reservoir numerical simulation model of the CO2 injection and storage process, and simulating to obtain a reservoir pressure field and a CO2 saturation field under different time steps; carrying out dynamic rock mechanics calculation to obtain dynamic fracture pressure fields of the cover layer under different time steps; and coupling the reservoir pressure field, the CO2 saturation field and the dynamic fracture pressure field, and carrying out transverse and longitudinal leakage risk dynamic evaluation. The technical problems that in the prior art, a simplified geologic model or a coarse mesh model is generally adopted, complex geologic and mechanical characteristics cannot be accurately described, the long-term stability of the storage body cannot be accurately evaluated, and the safety and long-term stability of storage are affected are solved.

The invention provides a method and device for determining a formation pressure coefficient after shale gas well fracturing, a computer readable storage medium and electronic equipment. The method comprises the steps of calculating well bottom fracture pressure values of all sections of a horizontal well according to pressure response values after a bridge plug ball is pumped into a well, then calculating a minimum horizontal principal stress value according to pressure drop, well opening pressure and well closing pressure after fracturing pump stopping for a certain time, and correcting a maximum horizontal principal stress value according to an indoor test and well logging method to obtain a well bottom fracture pressure value. And finally, reversely deducing a formation pressure value according to a fracture pressure calculation formula based on the well bottom fracture pressure value, the minimum horizontal principal stress value and the maximum horizontal principal stress value.

The invention discloses a top plate hydraulic fracturing pressure relief effect pre-evaluation method based on microseism monitoring, which comprises the following steps of: firstly, acquiring a rock stratum distribution condition in a fracturing range, determining the position of a fractured rock stratum, determining an overburden load according to the position of the fractured rock stratum and physical and mechanical parameters of the rock stratum, and calculating a fracture step pitch of the fractured rock stratum; further calculating the maximum bending deformation energy when the fractured rock stratum is broken; the fracturing effect evaluation step pitch is determined according to the roof fracturing construction scheme; counting micro-seismic events in the fracturing period in each evaluation step range, and calculating the ultimate bending deformation energy accumulated in the fractured rock stratum in the evaluation step range; and finally, calculating the hydraulic fracturing pressure relief degree based on the micro-seismic event and the ultimate bending deformation energy in the fracturing period in each evaluation step range, and determining the hydraulic fracturing pressure relief effect in combination with an evaluation standard. In the process, monitoring sensors do not need to be arranged underground, and under the condition that the working face is not mined, the middle-high-position hard rock stratum fracturing effect can be accurately pre-evaluated.

The embodiment of the invention discloses a low-permeability oil reservoir augmented injection method and device, a terminal and a storage medium, and belongs to the field of oil reservoir development. The method comprises the steps that for any well group of the low-permeability reservoir, the water well augmented injection amount of the well group is determined based on the accumulated production volume and the accumulated injection water volume of the well group; determining a preset crack length of the oil layer based on the minimum oil-water well distance of the well group; based on the water well injection increasing amount and the preset crack length, the stage water injection amount and the pump stopping duration of the high-pressure pump truck are determined; based on the stage water injection rate and the pump stopping duration, the high-pressure pump truck is controlled to inject water into the oil layer multiple times through the water injection well under the pressure higher than the fracture pressure till the accumulated water injection rate is equal to the water well injection increasing rate. According to the technical scheme, the high-pressure pump truck can be controlled to inject water into the oil layer at the pressure higher than the fracture pressure, cracks can be formed in the oil layer while oil layer energy is supplemented, the oil layer without the effect of conventional water injection can be obviously improved, and the problem that water cannot be injected into the low-permeability oil reservoir is solved.

The application discloses a method for exploiting coalbed methane by using a horizontal well group in a coal reservoir with an underpressure type, which comprises the following steps: arranging a horizontal well group, the horizontal well group comprising a predetermined number of horizontal wells, each horizontal well comprising a horizontal well section, and each horizontal well section being located in a coal reservoir of the same layer system; dividing each horizontal well section into a plurality of fracturing sections with a predetermined length, perforating a perforation position in each fracturing section to form a fracturing point; performing fracturing construction on each fracturing section, the fracturing construction comprising a liquid injection and energy storage fracturing stage and a main fracturing stage, in the liquid injection and energy storage fracturing stage, a first part of liquid is injected into the coal reservoir through the fracturing point at a predetermined discharge capacity and a predetermined construction pressure to fill natural fractures and cleats of the coal reservoir, in the main fracturing stage, a second part of liquid is injected into the coal reservoir through the fracturing point to form artificial fractures in the coal reservoir, and the predetermined construction pressure is not higher than a formation fracture pressure of a region where the horizontal well group is located; and after all the fracturing sections complete fracturing, coalbed methane exploitation is performed.

The invention discloses a shale fracture pressure continuous depth evaluation method and device, electronic equipment and a storage medium. The method comprises the following steps: determining a first physical characteristic parameter of target shale; and according to the first physical characteristic parameter of the target shale, the fracture pressure of the target shale is determined through a fracture pressure model. According to the scheme, the bursting pressure model is established in advance according to the reference shale core physical characteristic parameters and the reference shale core bursting pressure, after the first physical characteristic parameters are obtained, the bursting pressure of the target shale can be directly obtained according to the bursting pressure model, and it can be avoided that in an existing determining method, the bursting pressure of the target shale cannot be obtained. Errors generated when multiple pieces of parameter data are evaluated through the logging data, so that the accuracy of shale fracture pressure prediction is improved, and meanwhile, the acquisition of the fracture pressure can provide an accurate data basis for other geological exploration and development activities.

The invention relates to the technical field of geological engineering survey, in particular to a hydraulic fracturing multidirectional ground stress measuring device and method.The hydraulic fracturing multidirectional ground stress measuring device comprises a device body, an extrusion mechanism, an angle adjusting mechanism, a pressure meter and an angle measurer, the device body is deployed in a drill hole, and the extrusion mechanism is arranged on the device body; the adjusting part of the angle adjusting mechanism is connected with the extruding part of the extruding mechanism; according to the invention, the independent angle adjusting mechanism and the extrusion mechanism are arranged, so that fracturing pressure can be applied to the rock wall in any selected direction in the drill hole, the hypothesis limitation of isotropy of the rock mass in the traditional method is eliminated, and the crustal stress of anisotropic rock masses such as shale and the like can be measured in multiple directions; and therefore, stress field data more conforming to actual geological conditions can be obtained.

The application provides a method for calculating the ground stress based on the whole process formation leak-off test of a directional well, comprising the following steps: performing the whole process formation leak-off test on the target directional well and recording the test data; calculating the horizontal minimum ground stress and the overburden pressure according to the test data of the whole process formation leak-off test and the rock mechanics characteristic parameters of the target directional well; calculating the fracture pressure value under all possible arrangement combinations of the horizontal maximum ground stress and the horizontal minimum ground stress at the well deviation azimuth of the target directional well according to the stress distribution around the well section of the formation leak-off test well and the tensile failure criterion; drawing the contour map of the fracture pressure to establish the ground stress query chart of the target directional well; and querying the horizontal maximum ground stress corresponding to the calculated horizontal minimum ground stress in the ground stress query chart. The application calculates the ground stress based on the test data of the whole process formation leak-off test of the target directional well, and effectively improves the accuracy of the calculation result of the ground stress size.

The present invention proposes a numerical simulation method and system based on the coupling of rock fracture expansion and seepage, which belongs to the field of rock mechanics. Rock is regarded as a collection of particles and their mechanical contact with each other, and a triangulated network is constructed based on the center of each particle; according to the geometric characteristics of the triangulated network, a seepage pipe network containing the interior and the periphery is constructed, and the network nodes and boundary nodes are determined; the permeability coefficient is calculated according to the position of the particles on both sides of the pipe, and the pipes that are not 0 and pass through and connect the boundary nodes are used as passage pipes to form a through seepage channel and fracture network; a flow conservation equation group is constructed based on the network nodes, and the Jacobi iteration method is used to solve the pore pressure, calculate the fracture pressure, and apply it to the model to realize the coupling of stress field and seepage field. The present invention gives full play to the advantages of particle discrete element method in calculating rock fracture expansion and pipeline network method in calculating fracture seepage, and realizes the accurate simulation of rock fracture initiation and expansion, seepage channel identification and seepage field calculation.

The application relates to the technical field of sand prevention technology, and discloses a hydrate exploitation sand prevention technology control method and system. The method comprises the following steps: calibrating a pressure threshold and a friction baseline according to a fracture pressure gradient; decoupling agent friction and formation pressure drop according to a radial flow model; adjusting frequency and displacement according to an increment ratio linkage; carrying out double-tank uninterrupted injection; and curing according to a temperature-determined setting time. The application improves the rationality of sand prevention technology squeeze displacement setting and the reliability of setting curing.

The present invention discloses a method for optimizing the soaking time based on the hydration expansion stress. Considering the high content of shale clay minerals, after the rock undergoes a hydration reaction with the fracturing fluid, induced microfractures are generated due to disintegration, softening and expansion, improving the overall permeability of the reservoir, so as to maximize the soaking construction effect after fracturing. The method obtains the fracture pressure and pore pressure through a two-dimensional pore model and logging in-situ stress data, in combination with the rock tensile strength failure criterion; obtains the dynamic moisture content profile through a forced imbibition model and a moisture diffusion equation; obtains the hydration expansion stress through a three-dimensional stress-strain mathematical model of rock mechanics; combines the conditions for crack generation in the force field with the force field changes under different soaking days to obtain the optimal crack length and the corresponding shortest soaking time. The soaking time optimization method provided by the present invention can reduce the construction time and improve the construction effect.

The application provides an acidification fracturing fracture pressure prediction method considering rock mechanics property acid erosion degradation. The method comprises the following steps: subjecting the acid-eroded rock sample to uniaxial compression experiment and splitting experiment respectively; obtaining an acid-eroded rock mechanics parameter-acid erosion temperature-acid erosion time model according to the uniaxial compression experiment data and the splitting experiment data; integrating the acid-eroded rock mechanics parameter-acid erosion temperature-acid erosion time model into a conventional formation fracture pressure model to obtain an acidification fracturing fracture pressure prediction model considering rock mechanics property acid erosion degradation. The method comprehensively considers the influence of formation temperature and acid erosion time on reservoir mechanics property, can predict the acidification fracturing fracture pressure, and can provide a theoretical basis for field engineering parameter design.

The present invention discloses a proppant injection method based on particle size distribution optimization, comprising: comprehensively analyzing the geometric parameters of the fracture, the property parameters of the rock, and the pressure parameters that change in real time during the fracturing process, and determining the proppant particle size distribution range corresponding to different areas of the fracture through a data analysis model and algorithm; dividing the proppant particle size distribution range into a plurality of particle size adaptation intervals according to the width measurement values ​​and permeability test results of different areas of the fracture; during the proppant injection process, using downhole sensors to perform real-time data monitoring, and judging the areas in the fracture where proppant injection and distribution abnormalities exist based on the real-time data analysis, and performing dynamic particle size adjustment. The present invention solves the problem of uneven distribution of traditional proppant injection methods in complex underground environments. By constructing a multi-factor analysis model, key factors such as fracture geometry, rock properties, and fracturing pressure are accurately controlled to achieve refined regulation of proppant particle size distribution.

The application discloses a test method for studying the connection mechanism of hydraulic fractures and high-angle shear type fractures, and belongs to the technical field of indoor test of rock mass hydraulic fracturing. The test method for studying the connection mechanism of hydraulic fractures and high-angle shear type fractures preforms a through fracture at the side of a sample close to the top, performs high-temperature thermal shock treatment on the inner side of the through fracture, thereby forming a gradient damage zone, and processes a perforation upward in the middle of the bottom surface of the sample; the treated sample is placed in an experimental device, and a plurality of acoustic emission probes are pasted on the surface of the sample; a surrounding pressure and an axial pressure are sequentially applied by using a staged loading mode, then high-pressure water fracturing is continuously carried out in the perforation at a constant rate, and the fracture pressure and the corresponding flow rate are recorded when the sample is broken; the hydraulic fracturing process is analyzed according to the flow-pressure curve obtained by the test and the information collected by the acoustic emission probes, and the connection law of the hydraulic fracturing fractures and the through fractures is obtained by combining the CT three-dimensional reconstruction technology after the test.

This invention proposes a method and apparatus for predicting fracture pressure and production classification in tight oil reservoirs, relating to the field of reservoir exploration technology. The method includes: acquiring tight oil horizontal well data; extracting factors affecting fracture pressure from the tight oil horizontal well data, inputting these factors into a tight oil horizontal well fracture pressure prediction model to obtain the fracture pressure; extracting factors affecting tight oil production from the tight oil horizontal well data, inputting these factors into a tight oil production prediction model to obtain the tight oil production; classifying the tight oil horizontal wells according to the tight oil production to obtain tight oil production classification results; and generating a tight oil horizontal well development strategy based on the tight oil horizontal well fracture pressure and tight oil production classification results.

The present invention discloses a method and system for predicting the tensile strength of layered rock masses based on the Brazilian splitting test, which relates to the technical fields of rock mechanics and geotechnical engineering, and includes: performing Brazilian splitting tests on multiple groups of shale disc specimens with different bedding dip angles respectively to obtain initial experimental data; calculating the theoretical tensile strength based on the principle of the Brazilian splitting test; performing normalization processing on the initial experimental data and the theoretical tensile strength to obtain the experimental data after preprocessing; constructing a target relationship between the dynamic increase factor and the relative strain rate based on the experimental data after preprocessing; constructing a dynamic fracture pressure model based on the dynamic strength criterion of layered rock masses based on the target relationship and a preset static layered strength criterion to predict the tensile strength of layered rock masses. The present invention can not only perfectly fit the strength characteristic that the strength of layered rocks first decreases and then increases with the increase of the bedding dip angle, but also predict the dynamic tensile strength of layered rock masses within a certain strain rate range.

The invention discloses a method and a device for predicting ground stress of a deep coal bed gas and sand coal superposed reservoir. The method comprises the following steps: acquiring logging time sequence data of a to-be-predicted target area; constructing a bidirectional long-short-term memory network, respectively analyzing logging time sequence data based on progressive increase and progressive decrease directions of depth so as to output forward features and reverse features, fusing the forward features and the reverse features output by the bidirectional long-short-term memory network by using a multi-head attention mechanism, and calculating the elasticity modulus difference coefficient according to the elasticity modulus difference coefficient. Carrying out self-optimization processing on the bidirectional long-short-term memory network; according to the forward features, constructing a horizontal ground stress equation in combination with logging time sequence data, and calculating horizontal ground stress at different depths; according to the fracture pressure measured value of the logging time sequence data and the obtained horizontal crustal stress, an objective function is constructed to optimize parameters in a horizontal crustal stress equation in an inversion mode, and the optimized parameters are substituted into the horizontal crustal stress equation again to obtain target horizontal crustal stress of different depths through calculation.

This invention relates to a method for predicting fracture pressure in layered shale wells with extended reach based on a machine learning model. S1: Acquire drilled well data and collect downhole core samples, conduct anisotropic tensile mechanical experiments on shale along the bedding direction, and construct shale fracture criteria based on the experimental results; S2: Construct a fracture pressure model for layered shale wells with extended reach, and correct and integrate the calculated fracture pressure values ​​with field fracture test data; S3: Calculate the fracture pressure using a mechanical model based on the wellbore structure conditions of highly deviated wells, verify it using field low-pressure data, and form a fracture pressure calculation and analysis database; S4: Train the prediction model based on machine learning methods, determine the WT-LSTM model structure, set hidden layers, and train it; S5: Optimize the machine learning-based fracture pressure model through hyperparameter adjustment, feature selection, and importance assessment. This invention comprehensively improves the accuracy of fracture pressure prediction in highly deviated wells by integrating multiple factors, provides data support for the design of fracturing engineering in complex layered shale, helps to rationally select parameters for extended reach well construction, improves adaptability and safety, and provides data support for the development of layered shale oil and gas resources.

The present application belongs to the field of deep coal seam mining, and particularly relates to a mining area rock burst and gas efficient control method based on hydraulic fracturing; a plurality of working faces are designed in turn from bottom to top along the inclination, a return air roadway of the last working face is constructed, a mining area air inlet roadway is constructed at the lower part of the first working face inclination, then a bedding borehole is constructed to connect the return air roadway of the last working face and the mining area air inlet roadway, and hydraulic fracturing pressure relief and gas pre-drainage are performed. The return air roadway and the transportation roadway of the first working face are constructed from the transportation upward slope, and the return air roadway is left along the goaf during recovery as the transportation roadway of the next working face; ventilation is performed from the transportation roadway to the working face coal mining position and from the mining area air inlet roadway to the goaf; the gas in the coal seam is carried to the return air roadway of the last working face by the remaining working face bedding borehole and the hydraulic fracturing fissure, and is discharged. The present application can ensure the gas pre-drainage effect of the subsequent working face, and solve the problem of gas disaster caused by the goaf.