Full-Field Streamline Tracing in Complex Faulted Systems with Nonneighbor Connections Academic Article uri icon

abstract

  • Full-field flow simulators use a variety of cell geometries, ranging from simple rectangles to complex corner-point systems. One of the benefits of comer-point cells is the ease with which we may represent faulted reservoirs. Each face of a cell may be juxtaposed to two or more cells, depending on the fault throw and the lateral displacements of adjacent cells. Conventional finite-difference approaches routinely include the flux between these cells as "nonneighbor" connections. Other examples of nonneighbor or nonstandard connections occur at the boundary of local grid refinement (LGR) or local grid coarsening (LGC) regions where two computational grids come into juxtaposition. In each of these instances, the velocity across the nonstandard faces of a cell will be unevenly distributed according to the nonneighbor fluxes. In contrast, the standard streamline velocity interpolation model (Pollock's scheme) used within a cell assumes that the flux is evenly distributed on each cell face, inconsistent with the nonneighbor connection fluxes. Streamlines traced with such an approach do not have sufficient degrees of freedom to be consistent with the finite-difference fluxes and, consequently, will not follow a physical flow path. We propose a strategy that provides a consistent representation for streamlines and velocities near faults and nonneighbor connections. Our approach is based on a simple local (boundary layer) refinement construction that can be used to honor the fluxes at each face, without affecting the representation of flow within the cell or on any other cell face. The local refinement construction is the simplest extension to 3D for faulted reservoir cells that provides consistency with the finite difference flux calculation. Several examples will be presented for a single pair of cells juxtaposed across a fault and at LGR boundaries to illustrate the difficulties in conventional tracing algorithms and the benefits of our approach. The practical utility of our algorithm is demonstrated in a structurally complex and heavily faulted full-field model. The reservoir geometry includes multiple cells with complex fault juxtaposition and several nonneighbor configurations in different faces. This treatment is contrasted with the usual approach, and the implications for reservoir scale fluid flow tracing by streamlines is examined. Copyright © 2010 Society of Petroleum Engineers.

author list (cited authors)

  • Jimenez, E. A., Datta-Gupta, A., & King, M. J.

citation count

  • 13

publication date

  • November 2009