Method to increase oil recovery, from moderate to high viscosity oil deposits underlain by water, using steam injection

摘要

A method of heavy oil extraction from an underground reservoir containing heavy oil, of moderate to high viscosity, such oil underlain by a water zone within the same geological stratum, involves the injection of steam of varying qualities, or steam and other gases, via a horizontal steam injection well 4 into the water zone 2 underlying the oil zone 1. The production wells 3 are placed within the oil zone, laterally offset from the injection wells, and some way above the oil water contact so that water is not immediately produced. The steam injection well 4 is placed just below the oil water contact, in order to improve recovery of oil from the underground reservoir by preventing oil from being forced down into the water zone and rendered unrecoverable. It is suggested that an expanding steam chamber 5 is formed during steam injection, which serves to sweep the oil 1 towards the production wells 3.