US Patent 9890627 System and methods for controlled fracturing in formations

Controlled fracturing in geologic formations is carried out in a method employing a combination of alternating and impulsive current waveforms, applied in succession to achieve extensive fracturing and disintegration of rock materials for liquid and gas recovery. In a pre-conditioning step, high voltage discharges and optionally with highly ionizable gas injections are applied to a system of borehole electrodes, causing the formation to fracture with disintegration in multiple directions but confined between the locations of electrode pairs of opposite polarity. After pre-conditioning, intense current waveform of pulse energy is then applied to the system of borehole electrodes to create waves of ionization or shock waves with bubbles of heated gas that propagate inside and outside the high conductivity channels, resulting in rock disintegration with attendant large scale multiple fracturing.