24 results about "Discrete fracture model" patented technology

The invention belongs to the technical field of oil and gas reservoir energy development, and discloses a three-dimensional injection and production well pattern construction method based on a multi-objective algorithm. The problem that the delimited potential area is difficult to effectively use due to the fact that existing potential evaluation is only based on a single index is effectively solved. Comprising the steps that a fault inner core, a fault outer core, a fracture development dense zone and a secondary fracture zone are proposed; carrying out inter-well connectivity analysis on the oil reservoir units by utilizing an oil reservoir engineering method and a numerical simulation streamline method; based on the embedded discrete fracture model, analyzing a remaining oil distribution mode under the control of the nuclear band structure; a multi-parameter comprehensive evaluation system is constructed by combining the remaining oil utilization potential, the displacement power, the flow capacity, the connectivity relation and the reserve abundance; a three-dimensional injection-production well pattern construction technology is formed for an oil reservoir with or without bottom water; based on a multi-objective optimization algorithm, three-dimensional collaborative optimization of the recovery ratio, the well control reserves and the net present value is taken as a core, and a high-efficiency well location deployment technology for different fault zones is constructed.

The invention discloses a complex lithofacies shale oil reservoir multi-scale productivity prediction method and system. The method comprises the following steps: establishing a complex lithofacies shale oil reservoir model with a multi-scale aperture structure; representing the complex lithofacies shale oil reservoir model by adopting a dual-medium model and an embedded discrete fracture model; establishing a complex lithofacies shale oil reservoir seepage model and a numerical solution algorithm considering the starting pressure gradient and the stress sensitive effect, and forming a complex lithofacies shale multi-scale numerical simulation method; the complex lithofacies shale multi-scale numerical simulation method is adopted to carry out complex lithofacies shale oil reservoir seepage numerical simulation, and the shale oil reservoir oil and gas yield is obtained through calculation. According to the method, the seepage simulation and productivity calculation of the complex lithofacies shale oil reservoir can be quickly and accurately realized by establishing the seepage numerical simulation method of the complex lithofacies shale oil reservoir considering the multi-scale aperture characteristics, the starting pressure gradient and the stress sensitive effect.

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 discloses a fluid-solid coupling reservoir numerical simulation method considering fracture dynamic evolution, and relates to the technical field of complex oil and gas reservoir development, and the method comprises the steps: considering mass conservation and momentum conservation between a fracture and a matrix, and constructing a fractured reservoir model; building a fracture grid based on the embedded discrete fracture model; in each time step, solving a mass conservation equation and a momentum conservation equation, and updating parameters of a seepage field and a stress field; in each time step, judging whether the crack is opened, expanded or closed; the mass and momentum coupling relation between the newly opened fracture grid and the matrix and other fracture grids is constructed, and the mass and momentum coupling relation between the closed fracture grid and the matrix and other fracture grids is disconnected; and performing loop iteration until the simulation is finished. According to the method, the whole process of crack initiation, expansion and closing can be truly represented, the simulation precision is greatly improved, and technical support is provided for fractured reservoir production prediction and development scheme design.

The invention belongs to the technical field of oil-gas exploration and development, and particularly relates to an induced dynamic fracture numerical characterization method based on dynamic embedded discrete fractures. A dynamic embedded discrete fracture-based induced dynamic fracture numerical characterization method is characterized by comprising the following steps: determining an initial position for inducing the growth and extension of a dynamic fracture, and generating a dynamic embedded discrete fracture sheet for describing the growth and extension or closing process of the dynamic fracture at the moment by moment according to a time sequence by taking the initial position as a starting point; space splicing is achieved on the common boundary of the adjacent dynamic embedded discrete fracture pieces, the fracture is kept continuous as a whole, and then a dynamic embedded discrete fracture model covering and inducing the whole life cycle of the dynamic fracture is formed. Effective simulation of the water injection induced dynamic fracture growth extension and closing process in the energy storage and permeability enhancement injection process of the ultra-low permeability reservoir is achieved, and therefore effective technical guidance is provided for implementation of an energy storage and permeability enhancement technology mine field of the ultra-low permeability reservoir.

The invention relates to a buried hill gas storage effective gas storage space evaluation method, and belongs to the technical field of oil-gas exploration. The method comprises the following specific steps: acquiring fracture development parameters; determining the type of a storage space; reservoir logging response characteristics are determined; extracting buried hill cracks; establishing a bedrock geologic model and a bedrock buried hill discrete fracture model of the target area; and importing the results into a gas storage simulation model in the form of data flow, extracting effective gas storage spaces of a substrate and a crack of the buried hill gas storage, and determining a final buried hill building effective gas storage space. Through research on the method for calculating the reservoir space of the buried hill oil and gas reservoir rebuilt gas storage, the problem of invalid reservoir space calculation is deducted, the calculation accuracy is improved, and theoretical support is provided for calculation of the buried hill reservoir building capacity and later injection and production well position deployment.

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 provides a shale oil multi-well crosstalk diagnosis and optimization method based on EDFM and oil-water two-phase coupling, and belongs to the technical field of unconventional oil and gas development. According to the method, an embedded discrete fracture model (EDFM) is utilized to construct a multi-well platform physical model comprising a horizontal shaft, discrete hydraulic fracture networks and a shale matrix, the model is coupled with an oil-water two-phase flow conservation equation, fluid compressibility and fracture pressure sensitivity, and a non-adjacent connection conductivity operator between adjacent well fracture networks is innovatively introduced; the characterization module is used for characterizing a fracturing crosstalk path; and by simulating a double logarithmic pressure drop derivative curve in a multi-well soaking period, identifying pressure balance abnormity caused by adjacent well crosstalk. The defect that a traditional grid encryption technology is large in calculation amount and cannot process complex intersecting cracks is overcome, the position and the flow conductivity of the crosstalk cracks can be accurately recognized, and a scientific basis is provided for evaluating the platform well scale, optimizing the well spacing and the channeling prevention technology.

This invention discloses a method for determining the gas well penetration rate and pressure drop plot through proppant volume conservation numerical simulation, comprising: establishing a gas well numerical model of structural layers and dividing the development sub-layers; acquiring gas saturation and average adsorbed gas content data for each development sub-layer, and establishing three-dimensional models of free gas saturation and adsorbed gas saturation respectively; performing inversion to obtain artificial fracturing parameters; establishing an embedded discrete fracture model; dividing the embedded discrete fracture model into zones; acquiring stress-sensitive data and relative permeability data, and establishing stress-sensitive and relative permeability models; acquiring diffusion coefficient, reservoir temperature and pressure basic parameters, establishing embedded discrete fracture numerical models of fractures at different heights, and using the embedded discrete fracture numerical models to determine the fracture height range; establishing embedded discrete fracture numerical models under different penetration rate conditions, and generating a plot of the relationship between gas well penetration rate and pressure drop through numerical simulation calculation.

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.

This invention discloses a p-EDFM-based method for evaluating the productivity of marine-continental transitional shale gas. Addressing the vertical heterogeneity of marine-continental transitional shale, the matrix grid is layered, and physical property parameters and corresponding apparent permeability models for different rocks are introduced. The fracture surface is dimensionality-reduced based on artificial fracture parameters, and the crossflow coefficient is used to characterize the pressure exchange between grids. Further calculations of flow exchange between different grids are performed, and the productivity of each lithology can be obtained through stratigraphic tracing. The combination of a multiple continuous medium model and an embedded discrete fracture model overcomes the shortcomings of their respective models, better reflecting the widely distributed microfractures, large-scale artificial fractures, and heterogeneous stratigraphic characteristics of transitional shale gas reservoirs. In addition to evaluating the productivity of marine-continental transitional shale gas, the method proposed in this invention can also be extended to the productivity calculation of unconventional oil and gas reservoirs, demonstrating significant application value.

The stratum heat insulation barrier simulation method based on the projection type embedded discrete fracture model comprises the steps that a physical model of a well drilling area is constructed, the physical model is divided into a matrix grid and a barrier grid according to preset grid parameters, and the barrier grid is arranged in the matrix grid in an embedded mode; determining projection information of the barrier grid in the matrix grid according to different grid connection relations between the barrier grid and the matrix grid; determining geometric factors and geometric heat conductivity coefficients of the barrier grids according to the projection information; and inputting the geometric factor and the geometric heat conductivity coefficient into a preset model to obtain a heat transfer simulation result of the barrier grid. According to the scheme provided by the invention, mass transfer or heat transfer of the matrix grid and the barrier grid is accurately captured according to the geometric position and shape, so that a more accurate simulation result is provided, meanwhile, division of an unstructured grid is avoided, the complexity of equation discretization is reduced, and the calculation efficiency is greatly enhanced.

Reservoir simulation is performed by constructing an embedded discrete fracture model (EDFM) having matrix grid cells (180a) and extra continuum grid cells in the simulation grid. The EDFM is integrated into a multi-porosity-multi-permeability (MPMP) framework of a parallel reservoir simulator. Each fracture polygon of the fractures (181c) in the reservoir is divided into a set of fracture cells for calculating matrix-fracture connections (183b) and fracture-fracture connections (183b), which are all neighbor connections between grid cells that are face or edge neighbors. These neighbor connections may be intra-continuum connections or inter-continua connections that are stored in the matrix grid cells (180a) and / or fracture grid cells in the integrated EDFM / MPMP framework. The reservoir simulation is performed by the parallel reservoir simulator based on the cell connectivity data in the integrated EDFM / MPMP framework to facilitate well production of the reservoir.

The invention relates to a method and a device for calculating a mass exchange coefficient between bedrock and a fracture in an underground reservoir, and belongs to the technical field of seepage simulation of fracture type underground reservoirs. The method for calculating the mass exchange coefficient between the bedrock and the fracture in the underground reservoir comprises the following steps: performing embedded grid division on a bedrock region and a fracture region in the underground reservoir, and determining a connection pair between a fracture grid and a bedrock grid; based on the permeability of the bedrock grid corresponding to the connection pair, determining a Green element function under a bedrock grid permeability main axis coordinate system; source item coordinates in the Green element function are used as variables, integration is conducted on the Green element function along the fracture grids belonging to the same connection pair, and a pressure response function is determined; and based on the pressure response function, determining the conductivity between the bedrock grid and the fracture grid corresponding to the connection pair. According to the method, the calculation precision of mass exchange between the bedrock and the fracture in seepage simulation of the embedded discrete fracture model can be remarkably improved.

The application discloses a kind of deep fracture reservoir thermal flow coupling numerical simulation method and system based on mixed fracture model, and relates to fractured reservoir numerical simulation technical field.The method constructs three types of grid systems of large-scale fracture, natural fracture and matrix in the same calculation domain, respectively using embedded discrete fracture model and double-pore double-permeability model to be coupled representation.Through establishing four types of grid connection relationship, flow and thermal conductivity are calculated differentially, especially introducing improved Vermeulen function to carry out non-steady-state dynamic correction to the exchange between natural fracture and matrix.Based on finite volume method, fully implicit residual equation set is established and solved, and multi-field simulation results are output.The application considers the representation accuracy and calculation efficiency of multi-scale medium under the premise of not multi-level profiling of matrix, and can provide technical support for deep oil and gas reservoir injection-production development and geothermal field efficient exploitation.

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.

Reservoir simulation is performed by constructing an embedded discrete fracture model (EDFM) having matrix grid cells and extra continuum grid cells in the simulation grid. The EDFM is integrated into a multi-porosity-multi-permeability (MPMP) framework of a parallel reservoir simulator. Each fracture polygon of the fractures in the reservoir is divided into a set of fracture cells for calculating matrix-fracture connections and fracture-fracture connections, which are all neighbor connections between grid cells that are face or edge neighbors. These neighbor connections may be intra-continuum connections or inter-continua connections that are stored in the matrix grid cells and / or fracture grid cells in the integrated EDFM / MPMP framework. The reservoir simulation is performed by the parallel reservoir simulator based on the cell connectivity data in the integrated EDFM / MPMP framework to facilitate well production of the reservoir.

The embodiment of the invention provides a fracture model building method and system based on multi-stage crustal stress parameters, and belongs to the technical field of oil and gas exploration and development. The method comprises the following steps: executing target stratum structure recovery simulation based on geological detection data, and constructing an initial oil and gas reservoir framework body geological model; performing iterative simulation of the discrete fracture model of each stage to obtain a multi-stage discrete fracture initial model; constructing a target function between the multi-stage discrete crack initial model and the crack distribution data of the current target layer; calling a multi-objective function optimizer to execute objective function optimization, and obtaining a final multi-stage discrete fracture model based on an optimization result; and crack attribute parameter models are generated by stages based on the simulation result and the final multi-stage discrete crack model, fusion calculation of the crack attribute parameter models generated by the stages is executed, and a multi-stage stress superposition crack model is obtained. According to the scheme, the spatial distribution states of the cracks in different geological periods can be accurately represented, and a more accurate geological model is constructed.

The present application belongs to the technical field of oil and gas reservoir energy development, and discloses a kind of stereoscopic injection-production well pattern construction method based on multi-objective algorithm.Effectively solve the problem that the existing potential evaluation is only based on single index, which makes it difficult to effectively use the potential area divided.The method includes: proposing fault inner core, fault outer core, fracture development dense belt and secondary fracture belt;using reservoir engineering method and numerical simulation streamline method, analyzing interwell connectivity of reservoir unit;based on embedded discrete fracture model, analyzing remaining oil distribution pattern under the control of core belt structure;combining remaining oil producing potential, displacement power, flow capacity, connectivity and reserve abundance, constructing multi-parameter comprehensive evaluation system;for oil reservoirs with or without bottom water, forming stereoscopic injection-production well pattern construction technology;based on multi-objective optimization algorithm, taking three-dimensional collaborative optimization of recovery efficiency, well-controlled reserves and net present value as the core, constructing efficient well location deployment technology in different fracture zones.

The application discloses a shale gas supercritical carbon dioxide fracturing and production integrated simulation method and belongs to the fracturing technical field of petroleum engineering. The method comprises the following steps: S1, setting a fracture potential path based on natural fractures and in-situ stress, generating a fracture grid from the fracture potential path, and performing value assignment on the fracture grid; S2, simulating fracture deformation and fracture expansion by adopting a plane three-dimensional displacement discontinuity method, combining an embedded discrete fracture model and a component model to represent matrix-fracture fluid exchange, and performing supercritical carbon dioxide fracturing simulation through iterative coupling; and S3, performing production simulation with a pressure field and component distribution after fracturing simulation as initial conditions according to the opening of the fractures after fracturing simulation and the permeability calculated from the opening. The application can more accurately realize supercritical carbon dioxide fracturing and production integrated simulation, can provide technical support for tracking the migration path of carbon dioxide in the fracturing-well killing-production whole cycle and evaluating the feasibility of carbon dioxide storage after fracturing.

The invention discloses a method for constructing a rock mass permeation grouting model containing a complex fracture network based on COMSOL, which relates to the technical field of rock mass mechanics and solves the problem that fracture samples obtained collapse due to the shortcomings of low sampling efficiency and large sample capacity, resulting in a large difference between the established model and the actual project. The rock mass permeation grouting model construction method comprises conducting geological exploration on the rock mass, and extracting and processing fracture geometric parameters of the rock mass; performing fitting correction on each fracture geometric parameter to obtain an optimal distribution probability function; generating a discrete fracture network model based on the optimal distribution probability function by using a Latin hypercube sampling algorithm; converting the discrete fracture network model into a format so as to import it into COMSOL simulation software; performing geometric repair and multi-physical field coupling on the discrete fracture network model by using the COMSOL simulation software to obtain a virtual discrete fracture model, and performing entity verification, inversion analysis and grouting optimization to obtain an optimal discrete fracture model.

The present application discloses a method, device and storage medium for local grid encryption in a shale oil reservoir, which relates to the technical field of oil extraction and solves the problem in the prior art that local grids cannot be encrypted. The method includes embedding fractures into the original background grid and calculating the fracture conductivity; dividing the fracture control area according to the fracture conductivity, calculating the conductivity between the grids and the fractures in the fracture control area, further calculating the equivalent distance between the grids and the fractures in the fracture control area, setting a threshold value, and judging the size relationship between the equivalent distance and the threshold value; for the grids with conductivity greater than or equal to the threshold value, performing double-grid encryption multiple times until the conductivity of all grids is less than the threshold value; and recalculating the conductivity of the grids. This method realizes the encryption of local grids, reduces the influence of unsteady seepage on the accuracy of flow calculation, and improves the numerical simulation accuracy of the discrete fracture model embedded in the shale oil reservoir.

The present invention discloses a fluid-solid coupling reservoir numerical simulation method that considers the dynamic evolution of fractures. The method relates to the technical field of complex oil and gas reservoir development, and includes the following steps: constructing a fractured reservoir model by considering the conservation of mass and momentum between the fracture and the matrix; constructing a fracture grid based on an embedded discrete fracture model; solving the mass and momentum conservation equations at each time step and updating the seepage and stress field parameters; determining at each time step whether the fracture is open, expanding, or closed; constructing the mass and momentum coupling relationship between the newly opened fracture grid and the matrix and other fracture grids, and disconnecting the mass and momentum coupling relationship between the closed fracture grid and the matrix and other fracture grids; and iterating the simulation until the simulation is complete. The present invention can realistically reproduce the entire process of fracture initiation, expansion, and closure, significantly improving simulation accuracy and providing technical support for production prediction and development plan design for fractured reservoirs.

A method for performing fluid extraction from a fractured subsurface formation includes receiving a discrete fracture model representing the fractured subsurface formation and receiving pressure values and saturation values for multiple fluid phases across the discrete fracture model. Based on the pressure values for the multiple fluid phases across the discrete fracture model, face-centroid velocities are generated for the cells and the pressure values for the multiple fluid phases are updated by performing operations including a mimetic finite difference analysis. Based on the generated face-centroid velocities, an exit face and time-of-flight is determined for each cell and the saturation values are updated for the multiple fluid phases across the discrete fracture model based on the exit face and time-of-flight for each cell.