Numerical Simulation of the Dual Well SAGD Process in a Typical Heavy Oil Field in the Orinoco Belt, Venezuela

by
Gloria Katherine Pina, MSE

University of Texas at Austin, 1999
Supervisor: Mark A. Miller

Dual-well SAGD pilot tests have been successfully implemented in Canada's tar sands, and lately in the Tia Juana field in Venezuela, with quite positive technical results. Thus, there exists the motivation to determine the feasibility of its application to new areas.

The present work examines the impact of alternative operating conditions in forecasting the performance of dual-well SAGD in a heavy oil reservoir typical of the Orinoco Belt area, Venezuela using the Computer Modelling Group's commercial simulator, STARS.

The methodology in this report was to first validate the simulation by comparison against the results presented in the literature (Kisman and Yeung, 1995). The second step involved examination of the impact on SAGD performance of certain simulation parameters and operating conditions by comparison between pairs of cases.

Results for the sensitivity to simulation parameters included: a) refinement represents a marginal improvement in stability of the curves obtained from the simulation, and b) partial completion and/or utilization of an injector shorter than the producer generates a distortion of the steam chamber and disrupts the SAGD effect. The operating conditions sensitivity results included: a) use of a lower injection temperature allows for a more efficient process that recovers a higher amount of oil with lower steam-oil ratios, b) preheating the producing well during a start-up period represents only a marginal improvement over the process without it, and c) high production rate and/or high production bottomhole pressure rate cause the SAGD process to be less efficient in terms of recovery.

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