111 results about "Unstructured mesh" patented technology

A “near wellbore modeling” software will, when executed by a processor of a computer, model a localized area of a reservoir field which surrounds and is located near a specific wellbore in the reservoir field by performing the following functions: (1) receive input data representative of a reservoir field containing a plurality of wellbores, (2) establish a boundary around one specific wellbore in the reservoir field which will be individually modeled and simulated, (3) impose an “fine scale” unstructured grid inside the boundary consisting of a plurality of tetrahedrally shaped grid cells and further impose a fine scale structured grid about the perforated sections of the specific wellbore, (4) determine a plurality of fluxes / pressure values at the boundary, the fluxes / pressure values representing characteristics of the reservoir field located outside the boundary, (5) establish one or more properties for each tetrahedral cell of the unstructured grid and each cylindrical grid cell of the structured grid, (6) run a simulation, using the fluxes / pressure values at the boundary to mimic the reservoir field outside the boundary and using the fine scale grid inside the boundary, to thereby determine a plurality of simulation results corresponding, respectively, to the plurality of grid cells located inside the boundary, the plurality of simulation results being representative of a set of characteristics of the reservoir field located inside the boundary, (7) display the plurality of simulation results which characterize the reservoir field located inside the boundary, and (8) reintegrate by coarsening the grid inside the boundary, imposing a structured grid outside the boundary, and re-running a simulation of the entire reservoir field.

A targeted heterogeneous medium in the form of an underground layered formation is gridded into a layered structured grid or a layered semi-unstructured grid. The structured grid can be of the irregular corner-point-geometry grid type or the simple Cartesian grid type. The semi-unstructured grid is really unstructured, formed by arbitrarily connected control-volumes derived from the dual grid of a suitable triangulation; but the connectivity pattern does not change from layer to layer. Problems with determining fluid movement and other state changes in the formation are solved by exploiting the layered structure of the medium. The techniques are particularly suited for large-scale simulation by parallel processing on a supercomputer with multiple central processing units (CPU's).

A method, having application for hydrocarbon reservoir simulation, generates a hybrid grid, in order to carry out simulations in accordance with a defined numerical scheme, in three dimensions in a numerical scheme, of a heterogeneous formation crossed by at least one geometric discontinuity such as, an underground formation where at least one well has been drilled, or a fractured formation, by combining structured grids and unstructured grids. The hybrid grid includes a first structured grid for gridding the heterogeneous medium with second structured grids for gridding a zone around each discontinuity. A cavity of minimum size is automatically generated, with cells of the transition grid being an intermediate size between the size of the cells of the first grid and the size of the cells of the second grids.

A machine, computer program product, and method to enable scalable parallel reservoir simulations for a variety of simulation model sizes are described herein. Some embodiments of the disclosed invention include a machine, methods, and implemented software for performing parallel processing of a grid defining a reservoir or oil / gas field using a plurality of sub-domains for the reservoir simulation, a parallel process of re-ordering a local cell index for each of the plurality of cells using characteristics of the cell and location within the at least one sub-domain and a parallel process of simulating at least one production characteristic of the reservoir.

Example embodiments utilize machines to model reservoir geometry having geological layers as 2.5D unstructured grids. Example embodiments include program products to simulate a reservoir by generating a reservoir data system, performing a numerical fluid flow simulation, and visualizing the simulation. Data system embodiments include data structures to model a reservoir geometry as laterally unstructured two-dimensional (2D) grids and associated layer depths defining z-lines to thereby define a 2.5D unstructured grid, including datasets for: vertices of the grid cells for the future grid top and bottom surfaces, a number and listing of vertices for each grid cell, cell center coordinates, and vertex adjacency information using a compressed sparse row format. Computer-implemented methods include projecting external and internal boundaries onto a future grid surface; generating 2D unstructured, e.g., Voronoi, grids, for the top and bottom surfaces; and generating z-lines of depths corresponding to reservoir layers to thereby generate 2.5D unstructured grids.

A numerical simulation method for characterizing fluid channeling along large-aperture fractures of reservoirs relates to the field of petroleum reservoir development research and computational fluid dynamics. The conventional method can not effectively represent the rapid fluid channeling along large-aperture fractures. Aiming at solving the above technical problem, an advanced method is provided in the present invention. In the invented method, the geometric similarity and hydraulic similarity treatments of large-aperture fractures can be made simultaneously, moreover, the traditional numerical simulation software was improved to be an unstructured grid simulator. Therefore, the method of the present invention can effectively simulate the rapid fluid channeling along large-aperture fractures, consequently it can ensure the reliability of the simulation results and provide reasonable reference for the adjustment and optimization of oil field development plans. The present invention is simple in principle and easy to use, thus it has a great value of application and popularization.

Embodiments of the invention involve forming a prismatic grid and solving a convection-diffusion problem using the prismatic grid and mixed finite element analysis. The prismatic grid may be formed by providing a triangular mesh on a plane of a model. The mesh is then coarsened to make cells that are less desirable larger. The coarsened grid is then projected to form the prismatic grid. Each cell of the grid is then assigned a plurality of degrees of freedom. Mixed finite element analysis of the grid produces a matrix, which is then solved to yield a solution to the convention-diffusion problem.

A testing system for performing image based direct numerical simulation to characterize petrophysical properties of a rock sample under the simulated deformation condition, for example as representative of subsurface conditions. A digital image volume corresponding to x-ray tomographic images of a rock sample is segmented into its significant elastic phases, such as pore space, clay fraction, grain contacts and mineral type, and overlaid with an unstructured finite element mesh. A simulated deformation is applied to the segmented image volume, and the resulting deformed unstructured mesh is numerically analyzed, for example by way of direct numerical simulation, to determine the desired petrophysical properties.