Method for secondary recovery of oil
First Claim
1. A method of increasing the internal pressure in a fluid-bearing earth formation, comprising the steps ofestablishing at least two spaced apart boreholes extending into a subsurface earth formation containing both oil and other aqueous liquids,disposing a separate electrical conductor in each of said boreholes and into electrical contact with said aqueous liquids in said formation,insulating both of said conductors from substantially all earth materials adjacent said boreholes and lying above said subsurface earth formation to establish an electrical path composed of said insulated conductors and said formation materials extending therebetween,establishing an AC flow of electric current in said electrical path composed of said insulated conductors and said formation materials lying therebetween,electrochemically generating free hydrogen gas in said subsurface earth formation between said boreholes as a function of current intensity in said formation, andtrapping said free hydrogen gas in said formation to increase the pressure in said formation on said oil therein.
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Abstract
In one exemplar embodiment, method and apparatus include providing an electrode disposed in a plurality of vertically spaced boreholes penetrating the formation. The plurality of electrodes in contact with the salt water and oil of the formation are connected to a source of electrical power for establishing an AC electrical field of current flow between the spaced elctrodes. The electrodes are insulated from the earth structure surrounding the borehole for preventing an electrical current path between the electrodes and the earth structure for isolating the electrical current path from the electrode into the formation. The AC electrical current path through the formation generates volumes of free hydrogen in the formation where it is trapped for increasing the formation pressure. The increased pressure of the formation will drive the oil into producing boreholes spaced from the electrode boreholes.
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Citations
10 Claims
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1. A method of increasing the internal pressure in a fluid-bearing earth formation, comprising the steps of
establishing at least two spaced apart boreholes extending into a subsurface earth formation containing both oil and other aqueous liquids, disposing a separate electrical conductor in each of said boreholes and into electrical contact with said aqueous liquids in said formation, insulating both of said conductors from substantially all earth materials adjacent said boreholes and lying above said subsurface earth formation to establish an electrical path composed of said insulated conductors and said formation materials extending therebetween, establishing an AC flow of electric current in said electrical path composed of said insulated conductors and said formation materials lying therebetween, electrochemically generating free hydrogen gas in said subsurface earth formation between said boreholes as a function of current intensity in said formation, and trapping said free hydrogen gas in said formation to increase the pressure in said formation on said oil therein.
Specification