Induced Seismicity in Unconventional Reservoir Using a Viscoelastic Model for Wave Propagation

Abstract

This work presents a first approach to study the fracture orientation during water injection in an unconventional gas reservoir. The fracture propagation process is based on a breakdown pressure criterion: once pore pressure becomes greater than the breakdown pressure on a certain cell, that cell is fractured and it can become a micro-seismic event. For a given spatial distribution of weak stress zones (related to the breakdown pore pressure criterion), the flow simulations allow to obtain different orientations of micro-seismic event distribution caused by water injection. In this work, the reservoir is consider to have a fractal distribution for porosity and permeability, while the petrophysical properties for the seismic modeling are computed applying the Krief equation. Using the spatio-temporal distribution of the micro-seismic events information, the viscoelastic model for wave propagation generates the corresponding synthetic seismograms for each orientations. Each evaluated scenario yields different responses, showing the potential of the technique to detect the fracture orientation during water injection.