Vicous oil recovery method

Abstract

Solid hydrocarbon materials remaining in a subsurface earth formation such as, for example, the coke residue remaining in a subterranean tar sand deposit which has previously been exploited by means of a controlled oxidation process, is reignited and an oxygen-containing gas such as air is injected to burn the coke residue, thereby increasing the temperature of the sand or other formation matrix substantially. Water is then injected into the formation to absorb heat from the hot sand or formation matrix. Hot water and/or steam is thereby generated for use in thermal oil recovery methods in the immediate vicinity without the need for burning natural gas or other fuels which can be used more advantageously. Since the premeability of a tar sand formation is substantially greater at the conclusion of the controlled oxidaton reaction than it has initially, water containing appreciable solids suspended therein as well as minerals dissolved therein may be utilized without danger of plugging the formation, thus eliminating the cost of water treatment as would be required in conventional steam generation practice.