Mobil Oil Corporation

James M Sanchez

Randy D Hazlett

A method for reducing the time during which steam moves in a lateral direction between two parallel superimposed horizontal wells when utilizing a Steam Assisted Gravity Drainage (SAGD) process. Foam is added while injecting steam into an upper horizontal well once steam breakthrough occurs in an interwell region. Foam enters the interwell region thereby causing an increased pressure gradient. This increased pressure gradient adds to the gravity force thereby providing a greater interstitial oil velocity which increases oil drainage between wells during startup.

Method for reducing startup time during a steam assisted gravity

A solvent stimulation process whereby a viscosity reducing agent is circulated through a horizontal well via a production string. Said agent exits the production string and enters an annulus formed by said string and a liner. Said agent diffuses into the reservoir at a pressure below the reservoir pressure. As said agent diffuses through the reservoir under the influence of a concentration gradient, it reduces the oil's viscosity and makes it mobile. Simultaneously, oil of reduced viscosity migrates into the well under a pressure drawdown influence. A pseudo steady state production rate is achieved when convective movement of the oil of reduced viscosity is exactly counterbalanced by the diffusional rate of the viscosity reducing agent in a stimulated radial zone along said well. This stimulates a large volume of oil through the extensive surface area of the wellbore thus producing increased volumes of hydrocarbonaceous fluids from the reservoir.

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Dallas, TX, United States of America

James M Sanchez