Reservoir engineering aspects of light-oil recovery by air injection

This paper addresses the reservoir engineering aspects of air injection as an enhanced oil recovery technique for light-oil reservoirs. In its most su ccessful form, the process has been applied in deep, carbonate reservoirs. The development of this process in conjunction with an application of the i n-situ combustion (ISC) process to light-oil reservoirs, as well as them ma in mechanisms pertaining to ISC and to gas miscible flooding, are analyzed. It is seen that various air-injection processes (AIP's) can be classified, depending on their spontaneous ignition potential and gas miscibility at r eservoir conditions, into four different processes. Based on an in-depth li terature review, the best reservoir conditions for application of each of t hese four processes are derived. The main differences in operational aspect s (pollution, corrosion, safety) for these processes are also discussed. De sign considerations for pilot testing of the technique are presented. The c rucial point is location of the pilot on the structure, which is also a key element in its proper evaluation, and its subsequent development to a comm ercial-size operation. Finally, recommendations on laboratory work in suppo rt of design and evaluation of a field pilot are also presented.