Boundary and Crossfflow Behavior During Displacement in Nodai Systems

Abstract

Summary Conducting fault boundaries are common features in reservoirs, but realistic modeling of flow through such systems is difficult because the flow is grossly distorted, particularly at the nodes of the permeability contrasts. Standard finite-difference simulators use an uneconomical number of gridblocks and still do not represent the correct physical features. Nevertheless, the realistic simulation of faulted systems is essential for practical waterflood planning and consideration of EOR schemes. This paper presents an extension of a curvilinear grid technique to model the complex crossflow processes that occur in heterogeneous systems where nodes and boundaries are well defined. To test our methods, we performed experiments in a model nodal system and obtained displacement and streamline profiles for unit and nonunit mobility ratios for a permeability contrast of 2.5 and viscosity ratio range of 0.3 to 3.0. Grids were constructed by the numerical solution of a system of generating equations and incorporated into existing simulators. We show that the number of gridblocks required to model the systems effectively may be substantially reduced. This work demonstrates that there is scope for modifying grid generation for current simulators and incorporates more of the physical reality of the displacement processes in heterogeneities with nodes, such as faulted systems.