Chevron U.s.a. Inc.

James Preston Koffer

Raymond S Kasevich

Mark Dean Looney

Margaretha Catharina Maria Rijken

Jeb Xiaobing Rong

Embodiments of generating controlled fractures in geologic formation are provided herein. In one embodiment, a method comprises preconditioning by applying a sufficient amount of energy comprising AC power to the electrodes to induce an electrical field between opposite electrode contact points to generate a least one conductive channel between a pair of electrodes. The generation of the conductive channel is complete when current flow measured by a network analyzer exhibits a measured reduction of channel resistance of 90% ohms or more in 6 hours or less from when preconditioning first began. The method further comprises, subsequent to generating the conductive channel, fracturing by applying electrical impulses to the electrodes. The application of the electrical pulses generates multiple controlled fractures within and about the conductive channel. The energy is applied using a single phase configuration, a multiphase configuration, or any combination thereof.

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.

Controlled fracturing in geologic formations is carried out by a system for generating fractures. The system comprises: a plurality of electrodes for placing in boreholes in a formation with one electrode per borehole, for the plurality of electrodes to define a fracture pattern for the geologic formation; a first electrical system for delivering a sufficient amount of energy to the electrodes to generate a conductive channel between the pair of electrodes with the conductivity in the channel has a ratio of final to initial channel conductivity of 10:1 to 50,000:1, wherein the sufficient amount of energy is selected from electromagnetic conduction, radiant energy and combinations thereof; and a second electrical system for generating electrical impulses with a voltage output ranging from 100-2000 kV, with the pulses having a rise time ranging from 0.05-500 microseconds and a half-value time of 50-5000 microseconds.

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Delta, CO, United States of America

James Preston Koffer