An Investigation of the Feasibility of Air Injection into a Waterflooded Light Oil Reservoir

Abstract Insitu combustion or fireflooding has been extensively investigated and field tested in particular for heavy oil reservoirs. Despite many successfull projects of air injection into heavy oil reservoirs and the higher energy efficiency of insitu combustion process, application of the process has not increased due to high capital costs and complicated nature of the process compared with steam injection. In heavy oil operations air injection has been used primarily as a viscosity reducing agent. In this paper we address the problem of air injection into light oil reservoirs. Air injection / insitu combustion has been shown to be technically feasible in light oil reservoirs following waterflooding, but wide economic viability under tertiary conditions has not been firmly established. Air is a low cost injectant and unlike in the case of heavy oils the primary factor responsible for improved oil recovery is not just the viscosity reduction. In fact depending on the circumstances air injection into a light reservoir can serve a multiplicity of functions. Air injection at high temperature and pressure (deep reservoirs) could lead to unique economic and technical opportunities for improved oil recovery in many candidate reservoirs under both secondary and tertiary conditions, well beyond the traditional combustion applications. This paper describes the experimental and numerical work performed and the design of a suitable pilot to assess the feasability of air injection into a waterflooded light oil reservoir. Some of the advantages leading to improved oil recovery and the specific operational problems are discussed.