Exploration and Production Center, Research Institute of Petroleum Industry (RIPI), Tehran, I.R. IRAN
Gas injection into heavy oil reservoirs could result in high ultimate recovery of oil. Experimental studies showed that an application of a combined technology of Gas Assisted Gravity Drainage (GAGD) and Vapor Extraction (VAPEX) could increase final oil recovery of a candidate viscous oil reservoir. In this paper the results of laboratory investigation are presented, including Pressure-Volume-Temperature (PVT) studies, physical model experiments and simulation studies to evaluate the gas injection process for heavy oil reservoirs recovery. The study examined the effect of two different gases on viscosity reduction and oil swelling. Physical model tests were carried out to investigate the effect of gas injection on oil recovery. Another study (simulation model) predicted the performance of the reservoir under gas injection in a model. This simulation study was established on a sector of the reservoir.
 James, L., Chatzis, I., Details of Gravity Drainage of Heavy Oil During Vapor Extraction, SCA (2004).
 Butler, R.M. and Jiang, Q., Improved Recovery of Heavy Oil by Vapex with Widely Spaced Horizontal Injectors and Producers, JCPT, January (2000).
 Joshi, S.D., A Review of Horizontal Well and Drainhole Technology, paper SPE 16868 (1987).
 Butler, R.M. and Stephens, J.D., The Gravity Drainage of Steam Heated Oil to Parallel Horizontal Wells, JCPT, (1981).
 Joshi, S.D. and Threlkeld, C.B., Laboratory Studies of Thermal Aided Gravity Drainage Mechanism Using Horizontal Wells, Paper Presented at the Annual Advances in Petroleum Recovery and Upgrading Technology Conference, Calgary, 14-15, June (1984).
 Dumore, J.M. and Schlos, R.S., Drainage Capillary-Pressure Functions and the Influence of Connat. Water, SPE 4096 (1974).
 King, R.L., Stiles, J.H., A Reservoir Study of the Hawkins Woodbins Field, paper SPE 2972 (1970).
 Bansal, A. and Islam, M.R., Scaled Model Studies of Heavy Oil Recovery from an Alaskan Reservoir Using Gravity-assisted Gas Injection, JCPT94-06-05 (1994).
 Roa, D.N., Ayirala, S.C., Kulkarni, M.M. and Sharma, A.P., Development of Gas Assisted Gravity Drainage (GAGD) Process for Improve Light Oil Recovery, paper SPE 89357 (2004).
 Strickland, R.F., Morse, F.A., Gas Injection for Up Structure Oil Drainage, Paper SPE 7114 (1979).