ABSTRACT
The scaled crack and borehole surface pressure is shown in Figure 1 for aligned and tilted stress fields respectively as a function of the evolving crack path length. The pressure is scaled by the minimum principal field stress value, σ03 . During the initial unstable crack growth phase, the pressure is observed to fall and then to increase steadily as the fracture length is increased. It is notable as well that the initial pressure for the tilted stress field case is significantly greater that for the case of the aligned stress field.
