On the issue of the pressure recovery of a formation fluid

About the authors:

Elena I. Kuznetsova, Senior Lecturer, Department of the higher mathematics, institute of technology, National research nuclear university, MIPhI (Lesnoy)
Vadim S. Nustrov, Professor of Ural Federal University, Dr. Phys. and Math. Sci.
,

Abstract:

A considerable part of natural oil and gas formations are of fractured or fractured porous type. These formations are made up of nonporous or porous block matrices separated by a system of interconnected fractures. Such macroscopic properties of porous blocks and fractures as porosity and permeability differ radically. To analyze the filtration process in fractured porous formations they usually use linear approaches, among which is a popular linear model based on the dual porosity concept. Meanwhile, numerous field observations speak for high non-linear behavior of oil and gas fractured formations under their development. In this case linear models cannot be used to analyze the filtration process. To determine or update macroscopic parameters of formations in oil field practice pressure recovery processes are often used. Simulation results of pressure recovery in linear formations for Newtonian and non-Newtonian fluids can be found in publications. In the present article a nonlinear option of the double porosity concept is used. It is assumed that effective formation porosity and permeability depend heavily both on effective stress tensor and fluid pressure. Fracture porosity decreases when fluid pressure in fractures drops. This approach reflects main features of filtration processes in natural fractured formations. The elastic-plastic regime of the pressure recovery in a non-Newtonian fluid in a deformable fractured porous formation is considered. Field data interpretation is different as compared to linear models. Consequently, the obtained estimate of oil reserves can also differ.

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