Pressure-Dependent Water Loss from a Hydraulically Stimulated Region of Deep, Naturally Jointed Crystalline Rock

Abstract

The rate of water loss from a hydraulically stimulated region of naturally jointed of the stimulated region of naturally jointed crystalline rock is shown to be dependent on both the pressure and the pressure gradient. However, there is a threshold pressure above which the rate of water loss increases much more rapidly. Above this threshold pressure, further frowth and extension of the previously stimulated region occurs due to additional dilation and shear displacement of peripheral joints, as evidenced by greatly increases microseismic activity at the boundaries of the region. Therefore, the increased water loss at pressures above this threshold pressure is primarily due to fluid storage within the newly stimulated region, rather than to increased permeability losses at the boundaries.