1Department of Chemical Engineering, Persian Gulf University, Bushehr 75169, I.R. IRAN
2Petroleum University of Technology, Petroleum Research Center, Tehran, I.R. IRAN
3Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, I.R. IRAN
4Department of Chemical and Petroleum Engineering, Kansas University, KS, USA
The vapor extraction (VAPEX) process, a solvent-based enhanced oil recovery process has been found promising for some heavy oil reservoirs. In this work, the VAPEX process is studied using a compositional simulator on a number of single-block and multiple block fractured systems. PVT data of one of an Iranian heavy oil reservoir are used to tune the equation of state. Effects of fracture spacing on the performance of process were studied. It was found that the fracture network enhances the VAPEX process in low-permeability systems by increasing the contact area between solvent and oil contained in the matrix blocks. Also, the fracture network reduced the instabilities in the system pressure and damped pressure surges in the system during the VAPEX process. In addition, results showed that solvent traverse between fracture network delayed the onset of solvent breakthrough and provided more residence time for the solvent to be in contact with heavy oil. In other part, effect of well location on the performance of process was studied. It was found that the oil production decreased as the well spacing increased. When the injection and production wells were far from each other, the oil production was governed by displacement for quite a long time rather than the gravity drainage enhanced by the VAPEX process. Also, improper location of the injection and production wells may results in the shortcut between injector and producer, which would lead to early solvent breakthrough and increased gas production through the system. The well location is a critical issue when applying the VAPEX process in fractured systems.
 Saniere, A., Hénaut, I. and Argillier, J.F., Pipeline Transportation of Heavy Oils,A Strategic, Economic and Technological Challenge, Oil & Gas Science and Technology, Rev. IFP, 59(5), 455(2004).
 Butler, R. M. and Mokrys, I. J., Solvent Analog Model of Steam-Assisted Gravity Drainage, AOSTRA Journal of Research, 5(1), 17 (1989).
 Butler, R. M. and Mokrys, I. J., A New Process (VAPEX) for Recovering Heavy Oils Using Hot Water and Hydrocarbon Vapor, JCPT, 30(1), (1991).
 Butler, R. M. and Mokrys, I. J., Closed-Loop Extraction Method for the Recovery of Heavy Oils and Bitumens Underlain by Aquifers: The VAPEX Process, JCPT, 37(4), 41(1998).
 Butler, R. M., Mokrys, I. J. and Das, S. K., The Solvent Requirements for VAPEX Recovery, SPE 30293, Presented at the International Heavy Oil Symposium, Calgary, Alberta, Canada, June 19-21, (1995).
 Karmaker, K. and Maini, B. B., Applicability of Vapor Extraction Process to Problematic Viscous Oil Reservoirs, SPE 84034, Presented at the SPE Annual Technical Conference, Denver, Colorado, 5-8 October, (2003).
 Boustani, A. and Maini, B. B., The Role of Diffusion and Convective Dispersion in Vapor Extraction Process, JCPT, 40(4), 68 (2001).
 Butler, R. M. and Jiang, Q., Improved Recovery of Heavy Oil by VAPEX with Widely Spaced Horizontal Injectors and Producers, JCPT, 39(1), 48 (2000).
 Etherington, J. R. and McDonald, I. R., Is Bitumen a Petroleum Reserve?, SPE90242, Presented at the SPE Annual Technical Conference and Exhibition, Houston, Texas, 26-29 September (2004).
 Azin, R., Kharrat, R., Ghotbi, C., and Vossoughi, S., Applicability of the VAPEX Process to Iranian Heavy Oil Reservoirs, SPE 92720, Presented at the 14th SPE Middle East Oil & Gas Show and Conf., Bahrain, 12-15 March (2005).
 Rostami, B., Azin, R., and Kharrat, R., Investigation of the VAPEX Process in High Pressure Fractured Heavy Oil Reservoirs, SPE 97766, Presented at the SPE International Thermal Operations and Heavy Oil Symposium, Calgary, Alberta, Canada, 1-3 November (2005).
 “GEM User’s Guide”, ver. 2003, Computer Modelling Group (2003).
 Nghiem, L. X., Kohse, B. F. and Sammon, P. H., Compositional Simulation of the VAPEX Process, JCPT, 40(8), 54 (2001) .
 Cuthiell, D., McCarthy, C., Frauenfeld, T., Cameron, S. and Kissel, G., Investigation of the VAPEX Process Using CT Scanning and Numerical Simu-lation, Paper 2001-128, Presented at the Petroleum Society’s Canadian International Petroleum Conference, Calgary, Alberta, Canada, June 12-14 (2001).
 Dauba, C., Quettier, L., Christensen, J., Le Goff, C. and Cordelier, P., An Integrated Experimental and Numerical Approach to Assess the Performance of Solvent Injection into Heavy Oil, SPE 77459, Presented at the SPE Annual Conference and Exhibition Held in San Antonio, Texas, 29 September-2 October (2002).
 Das, S., Diffusion and Dispersion in the Simulation of VAPEX Process, SPE 97924, Presented at the SPE International Thermal Operations and Heavy Oil Symposium, Calgary, Alberta, Canada, 1-3 November (2005).
 Peng, D. Y. and Robinson, D. B., A New Two-Constant Equation of State, Ind. Eng. Chem. Fundam., 15, 59 (1976).
 Butler, R. M., Mokrys, I. J. and Das, S. K., The Solvent Requirements for VAPEX Recovery, SPE 30293, Presented at the International Heavy Oil Symposium, Calgary, Alberta, Canada, June 19-21 (1995).
 Aguilera, R., “Naturally Fractured Reservoirs, 2nd Ed., Penn Well Books (1995).
 Haugse, V., Reservoir Simulation of Fractured Carbonate Reservoirs, Workshop Presented at the 4th International ConferenceIOR, Tehran, Iran, January 22 (2005).
 Sigmund, P.M., Prediction of Molecular Diffusion at Reservoir Conditions. Part II-Estimating the Effects of Molecular Diffusion and Convective Mixing in Multi Component Systems, JCPT, 4, 53 (1976).
 Azin, R., Kharrat, R. Ghotbi, C., Vossoughi, Sh. and Rostami, B., Simulation Study of the VAPEX Process in Fractured Heavy Oil System at Reservoir Conditions, J. Pet. Sci. Eng., 60, 51 (2008).