Implementation of full permeability tensor representation in a dual porosity reservoir simulator.

摘要

Transport and flow phenomena in porous media and fractured rock arise in many fields of science and engineering, including petroleum and groundwater engineering. Over the past few decades, there are two classes of models that have been developed for describing flow and transport phenomena in porous media and fractured rock. They are the continuum and discrete models. Continuum models include single porosity and dual porosity models. The latter is popularly applied in simulating flow in naturally fractured systems.; Discrete feature models explicitly recognize the fracture system's geometrical properties, such as orientation and intensity. But shortcomings have been experienced for such discrete models in that large computational efforts are required for a realistic treatment of a heavily fractured system. Such a large fractured system may contain millions of fracture features. The huge demand of computational resources may seriously undermine the application of discrete models for such systems. Moreover, the discrete feature model is more difficult to use for multiphase flow and complex recovery mechanisms for oil recovery process.; The dual porosity model, a subclass of the continuum model, is a favorable approach to study flow in naturally fractured systems. In the dual porosity approach, it is assumed that the fissured porous media can be represented by two colocated continua called the matrix and the fracture system. High conductivity but low storativity typically characterizes the fracture system, whereas the matrix is usually characterized as low conductivity but high storativity. The matrix generally acts as a source that transfers its mass to the surrounding fractures; then fluid is transported to production wells.; There are two main reasons for the acceptance of dual porosity model. The first reason is its ability to handle the length scale inconsistency between matrix and fractures. It is impractical to simulate a fractured system by a single porosity approach if a matrix block is gridded to the fracture's length scale. But the dual porosity approach may divide the physical problem into two interactive problems.