The present invention relates to an improved method of recovery of petroleum from presently existing wells which are either non-producing or low production types. The method utilizes surges and oscillations of electrical energy in excess of 150 kilovolts involving the use of heavy current flow over a...http://www.google.de/patents/US4084638?utm_source=gb-gplus-sharePatent US4084638 - Method of production stimulation and enhanced recovery of oil
