Patent ID: 8596349

Claim:
A method of inducing fractures in at least a portion of a geologic structure, comprising: generating an acoustic wave in a fluid medium present in a borehole penetrating at least partially into the geologic structure, the acoustic wave being an ordinary acoustic wave having frequency, duration and amplitude sufficient for pressure to be applied relatively uniformly to the geologic structure to induce fractures in the portion of the geologic structure; and injecting pressurized fluid into a region proximate an electrode used to generate the acoustic wave wherein the injecting pressurized fluid comprises pressurizing the fluid in the borehole to a pressure below a threshold pressure above which the geologic structure would fracture prior to generating the acoustic wave; wherein within the pressurized fluid a gas bubble is formed expanding in volume inducing fractures in at least the portion of the geologic structure; and wherein the electrode is energized for a length of time greater than about 100 μs and at an energy of greater than about 1 kJ per pulse.