A Novel Approach to Effective Permeability Estimation for Modeling Naturally Fractured Reservoirs

Three different methods, the discrete fracture, dual and single continuum approaches, are currently used for simulation of naturally fractured reservoirs. A dual porosity or dual permeability approach is applied in simulation when fractures are well developed to form a flow network. On the other hand, the single continuum model, where the fracture system is represented by effective permeability, is commonly used if fractures are discrete or disconnected. Focusing on the latter case, this paper addresses several issues for characterizing naturally fractured reservoirs: an effective approach to determine equivalent or effective permeability tensors, the representative elementary volume (REV) for effective permeability determination, and application of the permeability tensor to flow simulation. The complex variable boundary element method is used to compute potential field and streamlines in two-dimensional fracture systems under the periodic boundary conditions. The complex potential at a point is expressed as summation of potentials for matrix, fractures, and fracture intersections. The fracture system is assumed to comprise infinitely thinfractures of infinite conductivity, and allowed to include discrete or intersected fractures.

Keywords:

fractured reservoir , permeability , modeling