Patent ID: 8846582
Filing Date: 2014-09-30
Classification: C09K,Y02P

Abstract:
1. A method of recovering oil from a reservoir, comprising injecting a viscosity reducing diluent into the reservoir via an injection well to assist oil recovery via a production well spaced from the injection well, wherein the diluent comprises an asphaltene precipitant which comprises carbon dioxide which is in supercritical state when injected into the reservoir and wherein the method also comprises injecting into the reservoir a further viscosity reducing diluent substance which is more polar than the asphaltene precipitant and which reduces asphaltene precipitation, wherein-said further viscosity reducing diluent substance comprises at least one aliphatic compound which consists of carbon, hydrogen and oxygen atoms only, contains from 4 to 70 carbon atoms and includes at least one of the following: a cycloaliphatic ring; an olefinic unsaturation; and an ester or ether group; with any oxygen atom being present within a said ester or ether group.