Fracture of Devonian Shale by Tailored Pulse-Loading. Final Report, August 15, 1977-August 15, 1978

摘要

The Department of Energy (DOE), Morgantown Energy Technology Center (METC) at Morgantown, West Virginia, is examining methods to increase production of natural gas from marginal reserves. Because of the potentially large reserves present in the eastern Devonian shales, these materials have been selected for the application and evaluation of novel and existing well fracturing and simulation techniques. As part of this program, SRI International has studied the feasibility of enhancing fracture formation and growth in well stimulation by tailored pulse loading, i.e., shaping the borehole input pressure-time history to produce a specified fracture pattern. Specifically, SRI's computational fracture model, NAG-FRAG, was used to evaluate the effect of pulse shape and rock properties in controlling dynamic rock fracture. Preliminary calculations were made of the amount and location of damage in a cylindrical configuration, and laboratory-scale springing experiments were performed to determine the NAG-FRAG fracture parameters of the Devonian shale. An exponentially decaying input pressure history was selected as the pulse shape for use in the final pulse shaping calculations.