MULTIPOROSITY MULTIPERMEABILITY APPROACH TO THE SIMULATION OF NATURALLY FRACTURED RESERVOIRS

This paper presents an array of deformation-dependent flow models of various porosities and permeabilities relevant to the characterization of naturally fractured reservoirs. A unified multiporosity multipermeability formulation is proposed as a generalization of the porosity- or permeability-oriented models of specific degree. Some new relationships are identified in the parametric investigation for both single-porosity and dual-porosity models. A formula is derived to express Skempton's constant B by Biot's coefficient H and relative compressibility phi*. It is found that the recovery of the original expression for Skempton's constant B is largely dependent on the choice of phi*, representing relative compressibility. The dual-porosity/dual-permeability model is evaluated through an alternative finite element approximation. The deformation-dependent fracture flow mechanism is introduced where the rock matrix possesses low permeability and fracture flow is dominant. A preliminary study of the reservoir simulation identifies the strong coupling between the fluid flow and solid deformation.