Fatique Weakening of Hard Rock with Cyclic Underbalanced Pressures

41076 November 20, 1996 Quest Integrated, Inc. Hard rock drilling is a difficult and expensive process that limits our ability to develop geothermal resources. This project will investigate methods of fatigue weakening the rock to increase the penetration rate and reduce the wear of conventional drill bits. Hydraulic power, available during drilling, will be used to drive cyclic pressure fluctuations, which are comparable to the tensile strength of hard rock. In Phase I, an experimental study will explore the relationship between drilling strength and the amplitude and frequency of the pressure fluctuations to fatigue rock. The feasibility of a drilling subassembly, capable of inducing high-amplitude cyclic pressure variations at the bit face, will be evaluated. Commercial Applications and Other Benefits as described by the awardee: The techniques should result in improved penetration rates in hard rock with indentation or drag bit cutters. Increased drilling rate in hard formations. This will allow for better utilization of geothermal resources by reducing the cost of exploration and production. The approach should also be effective for increasing drilling rates for oil and gas exploration.