Mobil Oil Corporation

Evin L Cook

Harry L Chang

Ralph F Burdyn

A method for the cyclic thermal stimulation of heavy oil adjacent producing wells to increase recovery of the oil produced therefrom by using an in-situ combustion process wherein oxygen or a fluid containing a minimum of about 75% by volume pure oxygen is injected into the well as the oxidizing medium, igniting the oil in the reservoir around the producing well so as to produce a combustion zone and to generate combustion gases consisting essentially of carbon dioxide and water in the form of steam, continuing injection of the oxygen until the combustion zone has propagated radially a distance of about 5 to 50 feet from the producing well, and thereafter recovering oil from the well. After terminating combustion, the well may be shut in for a period of time to allow the carbon dioxide and heat generated to more effectively permeate the reservoir adjacent the well prior to being returned to production status. The carbon dioxide dissolves in the oil reducing its viscosity along with the viscosity decrease resulting from the heat generated in the reservoir by combustion so that when the well is opened for production there is an improved flow of oil. The process of the invention applies to a single well or a plurality of wells spaced apart in a selected pattern with the various phases of the process cycles operated successively on the various wells in the pattern in any selected sequence.

Producing well stimulation method - combination of thermal and solvent

Oil is recovered from an oil-bearing reservoir in a process employing an in-situ combustion process utilizing a combustion-supporting gas containing at least 75% by volume pure oxygen, and preferably substantially pure oxygen, and a sequence in which the production well or wells are cyclically throttled. In place of using an in-situ combustion process, mixtures of steam and carbon dioxide or mixtures of steam and low molecular weight C.sub.3 -C.sub.8 hydrocarbons are injected into the reservoir and the production well is cyclically throttled. The production well flow rate is restricted until the bottom-hole pressure of the well has increased to an amount of about 30% to about 90% of the fluid injection pressure at the injection well. Thereafter, the production well is opened and oil is recovered therefrom as the bottom-hole pressure declines. The throttled production cycle may be repeated at appropriate intervals during the process.

Oil recovery method

Recovery of oil from subterranean oil reservoirs by waterflooding employing an alkaline agent and a sulfonate surfactant. An aqueous initiation slug containing an alkaline agent selected from the group consisting of alkali metal and ammonium hydroxides is injected into the reservoir via a suitable injection system. Thereafter an aqueous surfactant slug is injected into the reservoir behind the initiation slug. The surfactant slug contains a sulfonate surfactant and an alkaline agent. Subsequent to injection of the surfactant slug, an aqueous flooding medium is injected in order to displace the oil within the reservoir to a production system from which it is recovered. A portion of the flooding medium may contain a thickening agent for mobility control purposes.

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Dallas, TX, United States of America

Evin L Cook