Inventors:
James H. Cobbs - Tulsa OK
International Classification:
E21C 4110
Abstract:
A method of extracting hydrocarbon from an underground strata, wherein the hydrocarbon has high in situ viscosity, by the steps of forming a vertical access hole from the earth's surface to a point below the strata, the diameter of the access hole being sufficient to permit passage of workmen and machinery, mining an elongated horizontal shaft from the vertical access hole under the strata, establishing at least one drilling station in the horizontal shaft, drilling upwardly from the drilling station a plurality of wells into the hydrocarbon strata, the wells being spaced apart and preferably drilled so as to be substantially vertical in the hydrocarbon strata, injecting a viscosity reducing agent into one or more of the wells to reduce hydrocarbon in the strata to free flowing liquid, withdrawing the free flowing hydrocarbon from the strata through one or more of the wells, and pumping the withdrawn hydrocarbon to the earth's surface.