127 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 provides a shale reservoir fracture prediction method and system based on three-dimensional full-waveform inversion and a medium, and relates to the technical field of data analysis, and the method comprises the steps: arranging a multi-channel seismic exploration instrument in a shale reservoir region, and collecting full-waveform seismic data, including longitudinal waves, transverse waves and reflected waves; performing three-dimensional full-waveform inversion based on the logging data, the geological structure map and the full-waveform seismic data to generate a shale reservoir attribute model; a multi-scale inversion strategy is constructed, fracture sensitivity analysis and fracture form dynamic prediction are carried out, and reservoir fracture distribution characteristics and reservoir fracture form characteristics are obtained; discrete fracture point connection and fracture network reconstruction are carried out, a reservoir three-dimensional fracture network model is constructed, and fracture prediction visualization display is carried out. The technical problems that in the prior art, only inference based on limited data can be provided, comprehensive capture of a complex fracture network is lacked, distribution and form of fractures cannot be comprehensively and accurately described, and reservoir analysis and mining decisions are affected are solved.

The invention discloses a generative adversarial fracture network expansion simulation system and a method thereof. The system constructs a digital twinborn model of crack propagation based on a generative adversarial network. The generator adopts a 3D convolutional neural network structure and inputs geomechanical parameter tensors to generate a three-dimensional fracture network form; a discriminator is introduced into a physical constraint module, a fracture mechanical equation is embedded into a discrimination process to serve as a regularization item, and it is ensured that a generated crack meets mechanical rationality. In the training process, a crack fractal dimension evaluation algorithm is developed, the Hausdorff fractal dimension of the generated crack network is calculated, and the Hausdorff fractal dimension is compared with the real crack network fractal dimension to serve as constraint loss. In the application of shale oil horizontal well fracturing design, the matching degree of the fracture network generated by the system and the microseism monitoring result reaches about 89%, and the distribution optimization efficiency of the proppant in the complex fracture network is improved by about 3 times.

The invention discloses a coal seam induced fracturing method. A hydraulic fracturing fluid comprises a basic aqueous phase system and induced functional particles dispersed in the basic aqueous phase system. The prepared hydraulic fracturing fluid is injected into a target stratum at the set displacement and pressure, and an initial main fracture is formed in a reservoir by means of the fluid pressure; in the process, the functional particles in the fracturing fluid enter the crack tip and the potential branch position along with the fluid and are uniformly distributed in a crack channel; along with migration of the fracturing fluid in the stratum, the inducible functional particles act under different triggering conditions, so that the fracture system is evolved into a multi-direction and multi-branch fracture network from a single main fracture, and the transformation volume and the reservoir permeability are increased. Expansion or reaction can be triggered in the fracture, so that stress concentration is generated locally, secondary fracture formation is induced, a complex fracture network is constructed, and reservoir permeability is improved.

A hydraulic pulse-type soluble segmented acid fracturing slide sleeve and a pulse acid fracturing construction method. The slide sleeve comprises a slide sleeve outer cylinder (1) and a rotary valve assembly, and flow-passing holes (101) are formed on the slide sleeve outer cylinder (1); the rotary valve assembly comprises a valve core (2) and a valve ball (13), and the valve ball (13) can block a passage (203); a flow guide channel (206) and flow splitting channels (207) are formed between the outer wall of the valve core (2) and the inner wall of the slide sleeve outer cylinder (1); the slide sleeve outer cylinder (1) has a first position and a second position in the axial direction; when the valve core (2) is located at the first position, the outer wall of the valve core (2) blocks the flow-passing holes (101); an acid fracturing working fluid flowing through the flow guide channel (206) can push the valve core (2) to move from the first position to the second position along the slide sleeve outer cylinder (1), and push the valve core (2) to continuously rotate at the second position, so that the flow splitting channels (207) are alternately communicated with the flow-passing holes (101), the acid fracturing working fluid is discharged from the flow-passing holes as hydraulic pulses, hydraulic pulses with a proper frequency can be excited at the bottom of a well, energy attenuation is reduced, and the formation of a complex fracture network is promoted in a stratum.

The invention discloses a fractured reservoir acidification method based on a three-dimensional embedded discrete fracture model. The method comprises the following steps: S1, constructing a three-dimensional fractured reservoir physical model containing natural fractures; s2, carrying out structured grid division on the matrix, carrying out unstructured grid division on the crack by utilizing a matrix grid boundary, endowing physical parameters to the physical model, and setting acidification construction time; s3, fluid channeling coefficients between the matrix and the fractures and between the fractures are calculated; s4, based on the characteristics of the three-dimensional embedded discrete fracture model, constructing an acid liquor seepage model and an acid liquor chemical reaction model in the matrix and the fracture, and constructing a pore permeability evolution auxiliary equation of the matrix and the fracture; s5, coupling and solving the model and the equation in the S4; and S6, if the current time step reaches the construction time, obtaining a three-dimensional fractured reservoir acidification numerical simulation result. According to the method, high-precision dynamic coupling simulation of the three-dimensional complex fracture network and the acidification process is realized, and the method has a wide market application prospect.

The invention relates to a geological fracture recognition method based on multi-source geophysical data and a computer system, and solves the problem of high-precision recognition of tiny fractures and complex fracture zones. The method comprises the following steps: acquiring gravitational field model data, full-tensor gravity gradient data and aeromagnetic data of a target area, and carrying out gridding processing, pole conversion processing and edge expansion preprocessing on the data; performing boundary identification calculation on the preprocessed data by adopting a traditional physical field multi-derivative algorithm to generate a first group of boundary information A; carrying out boundary recognition calculation on the preprocessed data by adopting a gravity and full-tensor gravity gradient combined derivative algorithm (an enhanced total horizontal gradient derivative algorithm, a combined derivative algorithm and a combined oblique derivative algorithm) to generate a second group of boundary information B, and carrying out boundary recognition calculation on the preprocessed data by adopting an image edge detection algorithm to generate a second group of boundary information B; generating a third group of boundary information C; and carrying out weighted fusion on the three groups of boundary information to obtain a final fracture identification result.

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 application discloses a kind of acquisition methods, devices, media and electronic equipment of complex fracture conductivity, and its method includes: (A) extracting the specific form of complex fracture formed in stratum by hydraulic fracturing, calculating the average filling concentration of proppant in complex fracture;(B) complex fracture is divided into multiple simple straight fracture units, and the closure stress suffered by each fracture unit in stratum is calculated;(C) carry out simple straight fracture conductivity experiment, obtain the change curve of fracture conductivity with closure stress, and the relationship between fracture conductivity and closure stress is fitted;(D) the fracture conductivity corresponding to each fracture unit is calculated;(E) the fracture conductivity of each fracture unit is used to calculate the conductivity of the whole complex fracture.The application principle is reliable, simple to operate, and has strong practicability, can more accurately obtain the conductivity of complex fracture formed by hydraulic fracturing, and then provide effective guidance for hydraulic fracturing construction effect evaluation.

The invention provides a method and system for calculating the topological connectivity of a two-dimensional discrete fracture network containing n-type nodes, and the method comprises the steps: carrying out the binarization processing of an original fracture image of a rock surface, and generating a fracture binary image; extracting each crack region from the crack binary image based on connected domain analysis; extracting an outer contour pixel point set and a central axis point set of any crack region; an intersection point cluster is extracted from the central axis point set, and an effective extension point, located on the central axis, of each intersection point is obtained; determining the node type of each intersection point according to the number of the effective extension points of each intersection point; and calculating connectivity parameters of any crack region according to the node type of each intersection point of any crack region. Through the method, the node types in the two-dimensional discrete fracture network can be automatically identified, accurate quantization of connectivity is realized in combination with graph theory parameters, and the analysis precision and efficiency of the complex fracture network are remarkably improved.

The invention relates to a phase change clay fracture performance and failure characteristic test device, a prefabricated crack soil beam test piece, a servo motor, a sensor and a camera unit are arranged on a three-point / four-point bending moment loading frame, and the servo motor and the sensor are connected with a data acquisition unit. The invention also relates to a phase change clay fracture performance and failure characteristic test method. According to the invention, the compressive fracture process of the phase-change clay can be truly simulated, the fracture performance and damage characteristics of the phase-change clay in various complex fracture modes (including I-type, II-type and I-II-type fracture modes) can be accurately and reliably measured, and a premise can be provided for research of the fracture characteristics of the phase-change clay and analysis of core wall fracture damage and hydraulic fracture problems.

The invention discloses a calculation method of a rock mass fracture network seepage field containing a complex fracture form, and relates to the field of geotechnical engineering. The method comprises the following steps: for each node in a rock mass fracture network, determining a source-sink item at the node based on the flow of a plurality of fracture units connected with the node; substituting the source sink item at the node and the equivalent permeability coefficient matrix into an overall matrix equation of fracture network seepage for solving to obtain a pressure head value of the node; the overall matrix equation is obtained by assembling unit seepage matrix equations of all nodes in the rock mass fracture network; in the construction process of the fracture seepage unit equation, the influence of the on-way resistance coefficient on the equivalent seepage flow velocity of the fracture in the complex wall surface form and the influence of the local resistance coefficient on the equivalent seepage flow velocity of the fracture in the complex wall surface form are considered; and determining the pressure head values of all nodes in the rock mass fracture network as a rock mass fracture network seepage field. The method can improve the calculation precision of the fracture network seepage field.

The invention discloses a method and a device for predicting the productivity of a directional fracturing horizontal well of a complex fracture network shale gas reservoir. The method comprises the following steps: respectively establishing corresponding relations between shale gas viscosity, a compression factor, a compression coefficient and reservoir permeability and reservoir pressure; on the basis of the matrix grid model, hydraulic fractures are embedded by adopting a determined modeling method, and natural fractures are embedded by adopting a random modeling method; according to the fact that shale gas follows the Langmuir adsorption law in a matrix and follows the Darcy flow law in a crack, mass conservation equations of the matrix and the crack are established respectively; flow relations between adjacent matrix grids, between fracture grids, between matrixes and fracture grids and between crossed fracture grids are established respectively, and a matrix equation set of the horizontal well is obtained in combination with a Peaeman well equation; and solving to obtain the productivity data of the horizontal well. According to the method, reasonable productivity prediction can be carried out on the shale gas reservoir directional fracturing horizontal well under the constraint of the complex fracture network.

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 invention provides a method and apparatus for numerically discretizing complex fractures in shale reservoir fracturing. The method comprises loading an original numerical simulation background matrix grid and fracture polygons, parsing the fracture polygons, recording the fracture polygon coordinates, removing duplicate points from the fracture polygon coordinates, and characterizing the fracture polygons as a topologically consistent geometric structure based on the fracture polygon coordinates without duplicate points. Based on the topologically consistent geometric structure, the method calculates the fracture polygons intercepted by the background matrix grid when each fracture polygon is embedded in the background matrix grid. Connected fracture polygons within the background matrix grid are identified and grouped, and the conductivity between the background matrix grid and connected fracture polygons, and between connected fracture polygons and connected fracture polygons, is calculated. When calculating the conductivity parameters of embedded fractures, the method merges and divides fractures based on their connectivity, thereby improving the accuracy and efficiency of the calculation of non-connected fractures within the background grid.

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 provides a barite powder-based drilling fluid underground crack plugging effect three-dimensional CT image evaluation method, and belongs to the field of petroleum engineering, and the method comprises the steps: obtaining a three-dimensional CT image of a crack-matrix core model; a microscopic crack topological structure in the three-dimensional CT image is recognized, and a sealing agent material and barite powder-based drilling fluid are added; quantitatively evaluating the micro-crack filling effect based on the crack-matrix rock core model, enabling matrix pores to be equivalent to micro-cracks in the rock, and counting the micro-crack porosity of each layer; a three-dimensional reconstruction evaluation model is constructed, the plugging effect is analyzed, the error rate of the average porosity in a two-dimensional image and the porosity of three-dimensional core model crack filling reconstruction is calculated, and by establishing a complete evaluation technology system, the accuracy of crack plugging effect evaluation is improved, and accurate characterization of a complex crack network is achieved; a processing method for enabling matrix pores to be equivalent to micro cracks in the rock is innovatively provided, and multi-scale integrated analysis is achieved.

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 discloses a novel fracturing transformation method for a coal-bed gas well, and relates to the technical field of coal-bed gas exploration, development and fracturing. In order to overcome the defect that complex cracks are difficult to manufacture in coal seam fracturing transformation, the characteristics that original cracks of a coal seam are widely developed and distributed are utilized, the fracturing construction mode is improved, and the characteristics that fracturing construction increases coal seam stress, washes fracturing crack walls, releases stress rapidly in an open release mode and the like are fully utilized; according to the method, stress increase and rapid release are conducted on a coal seam for no less than one time, alternate stress action is conducted on native fractures, and the native fractures are damaged (activated), so that a seam net system which is wider in distribution and more complex in structure is formed, a wider channel is provided for migration of the coal seam gas, and the yield is further increased. The method has the four main characteristics that during fracturing construction, fluid flows in and out in two directions, stress increases and decreases in two directions, a coal seam stress release space is manufactured through erosion, and fracturing fluid and a propping agent are injected in a progressive increase mode.

The invention belongs to the technical field of geotechnical engineering, and particularly relates to a method and a device for preparing internal cracks of a cement mortar sample based on camphor sublimability. According to the invention, an alkaline reaction is blocked by the paraffin isolation layer, and the problems of residue, thermal damage and chemical interference in the traditional technology are solved by combining a sectional volatilization control process (paraffin isolation, supercritical CO2 dissolution, sectional volatilization and vacuum improvement). The refitted vacuum device realizes low-temperature efficient sublimation through pressure control and condensation recovery, and supports accurate preparation of a complex fracture network. Experiments show that the compressive strength loss of the sample is reduced to be within 5%, and the mechanical test precision is remarkably improved.

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.