Characterization of Unconventional Reservoirs Using Multiphase Flow and Seismic Wave Propagation Simulators

Abstract

The aim of this work is the study and characterization of tight gas and shale oil/shale gas reservoirs using numerical simulators of multiphase flow and seismic wave propagation in porous media. In these unconventional reservoirs the hydrocarbons production is carried out by hydraulic fracturing through the injection of fluids at high pressures. The effect of injection is a pore pressure increase, and, consequently, the zones of greater weakness are fractured, incrementing permeability and porosity values in the stimulated region. Thus, the modeling of fluid flow and the identification and characterization of fractures through seismic analysis are very important in these environments. A public domain Black-Oil simulator (BOAST) is applied to model the fluid injection process into the reservoir during hydraulic fracturing. This is combined with a fracture criterion based on a breakdown pressure and a subsequent updating of rock properties in the fractured zone. The fractures can be detected by applying a wave propagation simulator based on a poroviscoelastic model that includes attenuation and dispersion effects due to rock heterogeneities and the presence of fluids. To estimate the production of hydrocarbons, the BOAST is reapplied using as input data the static model of the rock and the pressures and saturations resulting from the fracturing process. The results show the ability of the described techniques to model the generation of fractures and, subsequently, to detect their presence.