Steamflood has been performed successfully since the 1950's in several fields worldwide. Although being considered successful, it still has problems associated with its mechanism. Due to gravitational effects, steam tends to move towards the upper portion of the reservoir causing the lower section to be poorly drained. In order to overcome this effect, water alternating steam process (WASP) might be a good solution which helps inhibiting the steam from moving upwards while keeping breakthrough-time from increasing. Previous literature study about WASP is scarce, even though this process is complex and sensitive to operating condition. By investigating WASP using response surface methodology, factors governing the steamflooding operations can be evaluated.

This paper presents the investigation regarding WASP applications in heavy oil. The reservoir model is ran with several operating conditions to achieve the most realistic interpretation. The operating variables include WASP start, WASP cycle, steam and hot water injection rate, and steam quality. Afterwards, a statistical model is fitted to examine the most important parameters influencing the 8-year net present value (NPV).

Simulation results indicate that the injection rate and WASP cycle are very sensitive to the NPV. The optimum case is that in which the WASP is started after 3.57 years, the cycle of steam-hot water injection is 4.65 months, the steam quality is 0.58, and the steam and hot water rate are 108 m3/day. The maximum NPV is 29.80 MMUSD.

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