55 results about "Complex fracture" patented technology

The present invention belongs to the technical field of fracture network optimization in oilfield exploitation. Specifically disclosed are a method and system for optimizing complex fracture networks in shale reservoirs. The method comprises: S1, on the basis of geological-engineering bimodal data fusion, constructing a three-dimensional digital twin of heterogeneous reservoirs; S2, synchronously calculating the interactions among fluid flow, rock fracturing and proppant transport during a hydraulic fracturing process; and S3, automatically and iteratively optimizing a combination of fracturing operation parameters. By means of constructing a closed-loop system consisting of geological modeling, multi-field coupling simulation, intelligent optimization and dynamic correction, efficient design and real-time optimization of complex fracture networks in shale reservoirs are realized.

The invention relates to the technical field of oil and gas reservoir development and geological modeling, and discloses a multi-scale factor constraint-based tectonic network fracture modeling method, which comprises the following steps of: synthesizing a Riemannian metric tensor field on the basis of earthquake, logging and geomechanics data, and defining non-Euclidean distance cost of a fracture expanded in an anisotropic medium; initial seed points are screened according to the elastic strain energy density, and initial growth potential energy in a limited range is distributed; solving the eikonal equation by using an anisotropic fast marching algorithm to carry out wavefront competitive growth, and dividing a grid region into generalized Voronoi units; identifying a wavefront contact interface, and extracting gradient features to judge a fusion or truncation type so as to establish fracture topological connection; and finally, tracking a geodesic line path along an anti-gradient direction to generate a three-dimensional discrete fracture network. According to the method, macro and micro constraints are unified through Riemannian geometry, clear physical significance is given to the fracture by utilizing an energy mechanism, and automatic and accurate construction of the complex fracture network topology structure is realized.

The invention discloses a tight gas reservoir rock compressibility evaluation method and system, computer equipment and a medium, and relates to the technical field of petroleum and natural gas development. The method comprises the following steps: testing to obtain rock sample parameters of a target reservoir rock sample; on the basis of the rock sample parameters of the target reservoir rock sample, the rock natural fracture crushing degree is obtained through calculation; based on the rock sample parameters of the target reservoir rock sample, obtaining the potential of reservoir transformation to form a fracture network; and according to the natural fracture crushing degree of the rock and the potential of forming a fracture network through reservoir transformation, calculating to obtain a rock compressibility index which is used for evaluating the rock compressibility. The rock compressibility is dynamically evaluated by comprehensively considering the natural fracture crushing degree and whether the potential of forming a complex fracture network through reservoir transformation can obtain high productivity or not, and technical support is provided for tight oil and gas exploration and development.

The invention discloses a design method capable of giving consideration to both toughening and crack path controllability for a brittle material, and belongs to the technical field of fracture mechanics and artificial intelligence crossing, and the method comprises the steps: employing an input coding method based on space-response double-domain fusion to carry out feature extraction; introducing a channel attention mechanism to perform weighted fusion on the extracted double-domain features, and generating prediction results for different key tasks; evaluating the reliability of a prediction result by adopting a phase field verification and closed-loop adaptive optimization mode, and carrying out iterative training and optimization on the neural network; and taking the optimized neural network as a fitness evaluation function of double-target genetic optimization, and performing multi-target optimization on defect generation parameters. According to the invention, through fusion of the spatial domain and the response domain, geometric morphology and dynamic response characteristics are cooperatively extracted, and the prediction precision of complex fracture behaviors is improved; through non-dominated sorting multi-objective optimization under physical constraints, a high-toughness and path-controllable optimal solution is output, and brittle materials are pushed to cross an active controllable fracture design.

The invention discloses a complex fractured rock mass physical reconstruction method based on deep learning, and belongs to the technical field of rock mass sample preparation. The method comprises the following steps: S1, quantifying rock mass characteristics by adopting a mechanical property target value and a fracture structure feature vector, and establishing a database; s2, constructing a multi-task deep neural network model based on an attention mechanism, and training the model; s3, determining the mechanical property and the fracture structure of a rock sample needing to be prepared, and acquiring corresponding 3D printing process parameters by adopting the trained attention mechanism-based multi-task deep neural network model; and according to the obtained 3D printing process parameters, a rock sample with required mechanical properties and fracture structures is prepared by adopting a 3D printing method. According to the method, mechanical property similarity and fracture structure fidelity are balanced, the high structural consistency of the prepared sample and the primary rock mass is ensured, the preparation process is repeatable, and a reliable sample is provided for a rock mechanical test.

The invention discloses a multi-channel injection system and method for an ultra-large rock core hydraulic fracturing experiment. The system comprises a three-dimensional injection array module, a modular injection panel, a variable impedance regulation and control unit, a dual-medium consistency injection module and a fluid-solid coupling compensation control unit. The method comprises the following steps: constructing a three-dimensional matrix type injection network, preparing sand-carrying fluid with uniform concentration, configuring initial fluid impedance to realize multi-channel flow matching, starting synchronous injection, monitoring pressure and stress signals in real time, and dynamically adjusting the impedance of each channel to compensate the heterogeneity of the rock core. And finally, a uniform and stable volumetric pressure field is formed and maintained in the ultra-large rock core, and meanwhile, the concentration deviation of the sand-carrying fluid between the channels is controlled within a preset threshold value. The technical problems that a pressure field in a large-scale rock core is not uniform, proppant conveying is not stable and multi-channel interference is not stable are solved, and the method is suitable for complex crack expansion and proppant laying mechanism research.

The invention discloses a magneto-rheological effect-based deep coal seam waterless fracturing yield increasing device and method.The magneto-rheological effect-based deep coal seam waterless fracturing yield increasing device comprises a fluid magnetization pretreatment tank, a directional fracture forming assembly, a monitoring assembly and a control terminal, and the directional fracture forming assembly comprises a proppant storage tank, a fluid mixing tank, a main pipeline, a plurality of magnetic field generators, a plurality of nozzles and a temporary plugging ball injector; the fluid mixing tank is connected with the fluid magnetization pretreatment tank and the proppant storage tank, the main pipeline comprises a longitudinal section pipeline connected with the fluid mixing tank and a horizontal section pipeline connected with the gas storage tank, the spray head is inserted into the side wall of the horizontal section pipeline, and the magnetic field generator is arranged in the horizontal section pipeline; the monitoring assembly comprises a magneto-dependent sensor and a micro-seismic monitor, the magneto-dependent sensor is arranged on the outer wall of the horizontal casing pipe, and the micro-seismic monitor is arranged in the horizontal casing pipe; the control terminal is electrically connected with the temporary blocking ball injector, the magnetic field generator and the monitoring assembly; in this way, the rock breaking efficiency is improved, water is not needed, a high-diversion complex fracture network system is formed, and it is ensured that fracture expansion is accurate and controllable.

The present application provides a shale gas complex fracture network characteristic parameter intelligent inversion method and system, the method adopts embedded discrete fracture model to establish the complex fracture network shale gas fracturing productivity model of shale reservoir; after determining the parameter value space to be inverted, the basic calculation examples are obtained based on random sampling, and parameter sensitivity analysis is carried out; the intelligent agent model is used to train the machine learning model with the basic calculation examples as the training samples, and the fracturing productivity prediction model is formed; the target example parameters meeting the error condition are optimized by using the set objective function based on the calculation results of the fracturing productivity prediction model; and then the target example parameters are brought into the complex fracture network shale gas fracturing productivity model to invert the target fracture network characteristic parameter results. The scheme can overcome the problems of time and cost consumption and limited applicability of the prior art, and can realize fast and reliable fitting by combining reservoir numerical simulation, intelligent machine learning model and optimization algorithm, and improve the shale gas complex fracture network characteristic parameter inversion efficiency.

The invention discloses a nuclear fuel particle fracture analogue simulation method based on a fracture phase field method, belongs to the technical field of nuclear fuel particle fracture simulation, and aims to solve the problems that the research efficiency is low and the application range of a numerical model is limited when a traditional method is used for a complex fracture condition. The method comprises the steps of building a phase field model, inputting material attribute parameters, setting boundary conditions of nuclear fuel particles, adding irreversibility constraints into an evolution equation of the phase field model, setting differentiated analogue simulation step lengths and outputting simulation results. Spatial distribution of phase field variables is used as characterization of a damaged area and a crack form, and real-time tracking of a crack tip position and an expansion path is not needed; for scenes such as multi-particle intersection cracks, branch cracks and irregular cracks which are difficult to process by a traditional method, accurate simulation can be realized only through phase field variable evolution without adjusting a grid or a calculation model.

The invention relates to the technical field of oil and gas exploitation, and particularly discloses an unconventional fracturing complex fracture network expansion simulation method based on uncertainty modeling, and the method comprises the steps: calculating the half length of a fracture based on perforation reservoir parameters obtained through logging and other methods in combination with an analytical fracture expansion simulation method; carrying out complex fracture network simulation by taking the fractal probability as a constraint and combining with a fracture growth algorithm with fractal probability random distribution characteristics to obtain reservoir complex fracture network form distribution; and finally, fracturing construction monitoring pump pressure fitting is performed based on an intelligent algorithm, the volume and form of the complex fracture network are inversely corrected, and real-time expansion simulation of the complex fracture network in the fracturing process is realized. According to the method, the complex branch fracture form can be depicted more finely, meanwhile, the calculation speed is high, and real-time simulation of the complex fracture net form in the fracturing process can be achieved; the method achieves the efficient and accurate simulation of the fracture form under the condition that the crustal stress of the reservoir is not clearly known, and provides an effective technical means for the fracturing construction design of the unconventional reservoir.

The invention discloses a sand adding pump injection parameter optimization design method and device. The method comprises the following steps: simulating a complex fracture form to obtain a digital fracture model; based on the digital crack model, simulating the laying forms of the propping agent under a plurality of different conditions contained in the orthogonal experimental simulation scheme to obtain corresponding laying concentrations; the plurality of different conditions are a plurality of different sand adding parameter and pump injection parameter combinations; according to the laying concentrations under the multiple different conditions and the corrected flow conductivity calculation model, flow conductivity values under the multiple different conditions are calculated respectively; inputting the distribution results of the flow conductivity values under the plurality of different conditions into a productivity prediction model, and predicting the yields in a preset time period under the plurality of different conditions; and determining a combination of the sand adding parameter and the pump injection parameter corresponding to the highest yield as an optimization design result. The invention provides a reasonable sand adding pump injection optimization design method, and effective guidance is provided for proppant pump injection scheme design of complex cracks.

The invention relates to a self-adaptive local mesh encryption method based on embedded discrete fractures, which comprises the following steps: aiming at a complex fracture system formed by horizontal well fracturing, establishing a two-dimensional tight reservoir physical model, carrying out initial mesh division, and adopting an EDFM method, two sets of independent mesh systems are adopted for the fractures and a matrix; determining a self-adaptive local grid encryption area; the method comprises the following steps: establishing a self-adaptive local grid encryption criterion based on crack distribution characteristics and physical flow rules, and automatically identifying a key region needing grid encryption: realizing a multi-stage grid encryption strategy, and establishing a tree-shaped hierarchical structure to manage a multi-stage encryption grid system; calculating a connectivity index CI after grid encryption; calculating conductivity, and constructing a conductivity matrix; and solving the pressure and the yield to realize fixed-production pressure solving and fixed-pressure production solving. According to the method, the depiction capability of the embedded discrete fracture model on the flow characteristics near the fracture is improved, and the yield change condition of the fractured reservoir is accurately predicted.

The invention provides a frequency-varying azimuth anisotropy seismic response characteristic analysis method for a complex fractured reservoir, and belongs to the technical field of oil and gas development, and the method comprises the steps: constructing an equivalent medium model which comprises a plurality of groups of vertical-vertical orthogonal fractures and is partially saturated with fluid in the fractures based on a Chapman multi-scale fractured medium theory; based on the model, frequency variation and azimuth anisotropy stiffness matrixes are deduced, the frequency variation azimuth stiffness matrix is embedded into the anisotropy reflectivity theory, and the PP wave frequency variation azimuth seismic forward modeling method is provided. And finally, respectively designing a single interface and thin layer reflection model, analyzing fracture geometric parameters (density, radius and porosity), partial saturated fluid parameters (saturation and plaque parameters), a PP wave frequency change reflection coefficient under a thin layer thickness change condition and a seismic azimuth response change rule thereof, and revealing control factors of frequency change azimuth response of the fractured reservoir. And a revolutionary numerical simulation method is provided for sweet spot prediction and fluid identification of the complex fractured reservoir.

A method for simulating hydraulic fracture expansion in a heterogeneous complex fracture network comprises the steps that rock mechanical parameters needed by simulation are obtained, complex fracture modeling is achieved through secondary development of a numerical simulation custom script, and a global cohesion unit is inserted; after global cohesion units are inserted, rock material parameters are described through Weber distribution, and rock mechanical parameters are endowed to the cohesion units, so that the heterogeneity of the reservoir is reflected, the formation and expansion process of a complex fracture network in the heterogeneous reservoir is simulated, and finally, the expansion behavior of the fracture network is simulated; according to the method, the formation and evolution process of the fracture network under the complex geological condition can be researched, and particularly under different geological stresses and external forces, how the fractures expand and interact to form the complex network is researched, so that the fracture behavior in the heterogeneous reservoir is deeply understood.

The invention provides a method for determining the migration distance of nuclide in a fractured rock mass by considering multistage decay, and relates to the technical field of radioactive waste deep geological disposal safety evaluation. According to the method, a random discrete fracture network rock mass model is constructed based on actual site geological information or statistical laws, a unified pipe network method is adopted to discretize a fracture-matrix system into a flow network formed by nodes and pipelines, and a coupling discrete control equation set of multi-nuclide migration is established under the framework; convection, dispersion, diffusion, adsorption retardation and multistage decay processes are synchronously depicted. Spatial and temporal distribution data of nuclide concentration are obtained through numerical solution, the farthest migration distance of mother nuclide is extracted, fracture connectivity density parameters are introduced to carry out quantitative analysis on fracture structure influence, and then an empirical relational expression used for predicting the maximum migration distance is obtained through fitting. According to the method, the nuclide migration ability can be rapidly evaluated under the complex fracture condition, and a quantitative basis is provided for radioactive waste disposal safety evaluation.

This invention discloses a method and system for evaluating the sealing performance of caprocks in aquifer reservoirs using a caprock-reservoir assembly. Foamed cement is used to adjust the mix proportions to obtain a transition layer similar in density and porosity to the caprock, serving as a bond between the caprock and reservoir. This system can be applied to caprocks of any lithology, fully considering the initial structural characteristics of the caprock, i.e., using pre-fabricated fractures to fully simulate the complex fractures or faults present in the original caprock. Gas leakage detection of the caprock body is conducted by simulating the cyclic injection and production of gas into the reservoir under simulated formation conditions. Real-time analysis of gas leakage along the caprock body allows for effective evaluation of caprock sealing failures and leakage caused by different types of caprocks and caprocks with different fracture characteristics during the injection and production process of the underlying reservoir. This provides a reference for establishing the upper limit operating pressure of aquifer gas storage facilities with different types of caprocks.

The invention relates to the technical field of surrounding rock fracture analysis, in particular to a surrounding rock sinusoidal fracture and complex fracture quantitative analysis method which comprises the following steps: step 1, finely extracting a fracture skeleton through a Unit + + model; 2, curve fitting is carried out, and the fracture form is represented in a mathematical form; 3, establishing a fracture clustering model, and grouping complex fractures; 4, evaluating and optimizing a fitting result by using a sine model; 5, calculating a JRC value based on the optimized morphological parameters; and finally completing result output and precision evaluation. According to the method, the automation degree and the analysis precision of identifying and quantifying the fractures from the complex borehole image can be effectively improved, and full-chain optimization from pixel-level segmentation to parametric modeling is carried out. According to the method, a powerful technical support is provided for realizing accurate quantification of a rock mass structural surface, reliable calculation of JRC and scientific evaluation of final rock mass stability, and the technical progress of mine safety and intelligent mining is remarkably promoted.

The present application relates to a kind of shale condensate gas well volume fracturing outer zone productivity contribution analysis method, method includes the following steps: based on the complex fracture network characteristics and oil-gas two-phase flow characteristics in the fracturing development process of shale condensate gas well, establish mathematical physics model based on three linear flow theory, the complex fracture network of shale condensate gas well is equivalent to be handled into fracturing reconstruction body, fracturing reconstruction body includes artificial main fracture, fracturing reconstruction inner zone and fracturing reconstruction outer zone;Based on the mathematical physics model of three linear flow theory, the history matching of shale condensate gas well dynamic production is carried out, and typical shale and fracturing crack parameter is obtained;Based on typical shale and fracturing crack parameter, the contribution degree of fracturing reconstruction outer zone to productivity under the condition of different fracturing reconstruction outer zone boundary length, different fracturing reconstruction outer zone permeability is analyzed, to give reasonable well spacing considering the contribution degree of fracturing reconstruction outer zone.

The present application relates to a multistage temporary plugging fracturing method and device based on stress cage effect and a storage medium, applied to the technical field of oil and gas exploitation, comprising: determining a plugging point by obtaining a stress weak position on a main fracture, determining the amount of temporary plugging diverting fluid by calculating the additional net pressure in the fracture required to generate a branch diverting fracture at the position with the minimum principal stress, plugging the position with the weakest stress in the main fracture to form an artificial barrier layer to prevent subsequent fluid pressure from being transmitted forward, thereby changing the ground stress field near the position to form an additional induced stress field, generating a stress cage effect, and realizing the formation of multistage temporary plugging branch fractures in a straight well; and overcoming the problem that it is difficult to form complex fractures by simply increasing the amount of liquid and the construction displacement to expand the liquid sweep range.

The invention belongs to the technical field of rock mass mechanics, and relates to a deep underground rock mass complex fracture field rapid refined inversion method comprising the following steps: collecting a rock image, carrying out binary conversion on the rock image, and calculating the fractal dimension of a binary image; marking central point coordinates of each fracture in the binary image, inputting the central point coordinates into a kernel density estimation model, generating a kernel density estimation curve, and calculating an optimal bandwidth value; calculating the kernel density value of the central point of each fracture by using the optimal bandwidth value, dispersing the to-be-researched region into equidistant grids, endowing each grid with a vertex weight according to the kernel density value, sampling data points in the to-be-researched region, and taking the data points as the central points of the fractures; and calculating the physical characteristics of the fractures, combining the fractal dimension, obtaining the number of inversion fractures, sampling the distribution rule of the physical characteristics, obtaining a statistical probability value, and distributing the physical characteristics to the central point of each inversion fracture according to the statistical probability value and the number of the inversion fractures for the inversion of the fracture field.

The invention discloses a flow conductivity testing system based on distributed optical fiber sensing and replaceable complex seams, and belongs to the technical field of oil field fracturing experimental equipment. According to the technical scheme, the device comprises a four-stand-column pressing machine, a complex seam rock core, a flow guide clamping device and a data acquisition control system; the complex seam rock core is formed by splicing and stacking multiple layers of rock plates, grooves are formed in all the layers of rock plates, all the layers of rock plates are spliced and combined, the grooves in the rock plates form cracks in the complex seam rock core, pressure sensors are arranged in the formed cracks, and outlets of the cracks are connected with an outlet metering module and a back-pressure valve; an optical fiber groove is formed in each layer of rock plate, and optical fibers are placed in the optical fiber grooves; a displacement sensor is arranged on the edge of each layer of rock plate; the complex seam rock core is placed in the flow guide clamping device, and the four-stand-column pressing machine is arranged outside the flow guide clamping device. The flow conductivity testing system provided by the invention not only can be combined into various complex fractures and can quickly replace the rock plate group, but also can simulate a real fracture network scale effect.

The invention provides a method and a system for evaluating a single-section well test based on a discrete fracture network technology. The method comprises the following steps: classifying fractures according to morphological characteristics of a fracture network; constructing a corresponding single-section well test interpretation model and a single-section well test mathematical model based on crack classification by using a discrete crack network technology; respectively inputting the well testing key parameters of each crack classification into a single-section well testing mathematical model, and drawing a single-section double logarithmic well testing curve of each crack classification based on a solving result; and analyzing the single-section double logarithmic well testing curve to obtain an evaluation conclusion of single-section well testing. According to the method, a discrete fracture model (DFN) is adopted for coupling matrix-fracture seepage, and the actual fracturing effect of the deep shale gas well and the complex degree of the fracture network are considered, so that the seepage characteristics of the complex fracture network are accurately represented; the influence of key parameters such as reservoirs and cracks on well test interpretation results is determined by establishing a single-section well test mathematical model, and the accuracy and reliability of well test fracturing effect evaluation under different crack classifications are improved.

The invention provides a volume fracturing optimization method for improving the single well yield of a tight oil reservoir. The volume fracturing optimization method comprises the following steps that (1) well selection and layer selection are conducted according to the purpose of increasing the reservoir transformation volume; on one hand, natural fractures are relatively developed, the natural fractures are communicated through fracturing, and net-shaped fractures are achieved; the brittleness index of the reservoir is high, and rock is prone to shear slippage to form complex cracks; 2) optimizing fracturing fluid systems in a prepad fluid stage and a sand-carrying fluid stage; and (3) fracturing construction parameters are optimized. According to a conventional tight reservoir volume fracturing design method and an underground micro-seismic test result, aiming at a tight reservoir with poor reservoir physical properties, developed natural fractures and high brittleness index, the method aims at increasing the reservoir transformation volume and improving the fracture complexity, and on the basis of a conventional conventional volume fracturing large-liquid-amount, high-displacement and low-mucus design mode, the method is suitable for the volume fracturing design of the tight reservoir and the underground micro-seismic test result. And the fracturing fluid, the pumping sequence of fracturing parameters and the technological property are changed, the reservoir transformation volume is further increased, and the single well yield is increased.

The invention provides a fracture identification method and device for an ultra-deep carbonate reservoir in a subsurface mountainous area, and the method comprises the steps: sequentially carrying out the preprocessing of an original post-stack depth domain three-dimensional seismic body of a target work area, and obtaining a preprocessed seismic body; inputting the preprocessed seismic body into a three-dimensional convolutional neural network model to obtain an initial fault probability body; performing superposition display on the initial fault probability body and the original seismic section to form an initial superposition graph, constructing a learning sample set and a verification sample set, and determining the optimal iteration weight frequency; a final optimized neural network model is constructed according to the optimal iteration weight times, and a fault probability body is obtained through recalculation; and performing parameterization post-processing on the recalculated fault probability body to obtain a final fault probability body, and taking the final fault probability body and the final superimposed graph as a final fracture identification result. According to the scheme, the technical effect of improving the recognition precision of complex fractures, weak fractures and small-scale fractures is achieved.

This invention provides a method for inverting fractures in coal and rock fracturing based on the distribution of surface and end cleavage. The method includes: calculating key rock mechanical parameters and geostress parameters of deep coal and rock; establishing a simplified coal and rock mechanical model including surface and end cleavage, calculating the stress intensity factor at the fracture tip and the critical stress for fracture initiation, and obtaining the initiation criteria for I-II composite fractures; after fracture initiation, using the maximum energy release rate criterion to determine the propagation problem when hydraulic fractures meet natural fractures; combining the fracture propagation calculation method based on lightning simulation, using the similarity principle to consider reservoir geological parameters, geostress distribution, and fracturing construction parameters, and using circumferential stress and critical fracture stress to determine the propagation range of secondary fractures; introducing random functions and fractal probability exponents to characterize the random distribution characteristics of fracture propagation, simulating the propagation of complex fracture networks, and obtaining information on fracture morphology, length, and branch fracture density.

This invention discloses a method for predicting the production capacity of deep coal and rock gas considering complex fracture networks. First, the method establishes a fracture network topological tensor matrix based on fractal geometry and non-Euclidean topological manifolds. Second, it introduces a nanoscale confined multi-state desorption operator to construct a cross-scale gas release source term and integrates continuum damage mechanics and phase field theory to generate a full-tensor permeability evolution functional. Subsequently, a kinetic model is established to quantify the conductivity attenuation boundary caused by coal powder bridging. Combining the above parameters, a spatiotemporal fractional derivative is introduced to construct a comprehensive flow field control equation characterizing nonlocal anomalous diffusion of fluids. Finally, this equation is mapped to a hypergraph network system for global order reduction solution. This invention effectively eliminates the computational singularity of multiphysics rigid equation sets, achieving efficient and high-precision prediction of deep gas well production capacity under time series, providing reliable support for formulating scientific drainage and production systems.

The invention relates to medicine and can be used for treating severe polytrauma and complex fractures, for example, of the tibia long bone. A robotized system for the closed reduction of a fractured femur comprises a system of actuators based on a Stewart platform, a working member assembly, Schanz pins, a perineal post, and a controller with software. The Stewart platform is mounted on a floor plate via a vertical column. The linear actuators are arranged between a base plate and an end effector having a C-shaped ring. The two ends of the actuators are connected by hinges to the base plate and the end effector, respectively. The Schanz pins are secured to mounting blocks which are fastened by round-head screws and wingnuts. The perineal post is mounted on a base plate via a vertical column. The post is connected to two additional links. An O-shaped ring of the perineal post is connected to the C-shaped ring by a trapezoidal steel ring. A Schanz pin is mounted on a steel block such as to be capable of holding a proximal fragment in place during the reduction process. The invention results in precise traction forces and the optimal alignment of bone fragments.

The application provides a multistage hydraulic fracture propagation control method, comprising: obtaining the mechanical parameters of the rock mass in the tunneling area; constructing a crack mechanics model based on the mechanical parameters, calculating the critical crack initiation pressure and the optimal fracture azimuth angle, so as to determine the lowest fracturing fluid injection pressure and the corresponding drilling angle; based on the joint surface stress model and the crack propagation criterion, regulating the fracturing fluid injection pressure to guide the hydraulic fracture to propagate according to the preset propagation mode. The multistage hydraulic fracture propagation control method realizes the accurate regulation and control of multiple types of crack propagation modes, so as to achieve the controllable construction of the complex fracture network and overcome the blindness of the traditional experience design.

The invention provides a preparation and test method of a special-shaped slurry-rock assembly in a high-pressure environment, and belongs to the field of preparation of special-shaped slurry-rock assemblies, and the preparation and test method comprises the following steps: selecting rock mass sections of the same batch, processing the rock mass sections into standard cylinder sizes, and prefabricating various fracture samples through linear cutting equipment; placing the fracture sample in a sample cabin, setting a confining pressure environment, and pumping slurry into the sample cabin according to a set grouting pressure; respectively monitoring the resistance change of the slurry and the pressure change of different heights in the sample cabin and recording the acoustic characteristics of the medium in the sample cabin; after grouting is completed, the mixture is placed in a curing box, and slurry-rock combination bodies in different forms are obtained after curing; a plurality of different types of artificial fracture samples are designed and prepared to simulate common complex fracture structures in actual engineering, so that the complex fractures are accurately and controllably prefabricated; and grouting and consolidation are carried out in a high-pressure environment simulating ground stress, so that the consistency and engineering applicability of the sample are ensured.

The present application relates to the technical field of fracturing aids, and is a temperature-controlled variable-density high-pressure-resistant proppant and a preparation method thereof.The raw materials of the temperature-controlled variable-density high-pressure-resistant proppant include a proppant, a surface modifier, a temperature-controlled polymer, an initiator and an organic solvent.The temperature-controlled variable-density high-pressure-resistant proppant is prepared by first modifying the surface of the proppant to obtain a modified proppant, then grafting and polymerizing the modified proppant with the temperature-controlled polymer, and finally post-treating the final product.The temperature-controlled variable-density high-pressure-resistant proppant can reduce the density under the response of the bottom-hole temperature, so that it is more easily transported to the deep part of a complex fracture network and uniformly laid, has a low breakage rate, can well support the fractures and promote the flow of oil and gas in the fractures.Meanwhile, the temperature-controlled variable-density high-pressure-resistant proppant still has high pressure resistance after swelling, so as to avoid being crushed to reduce the fracture width and block the seepage channel and reduce the fracture conductivity.