Numerical Evaluation of the Impact of Steam Quality on Steam Flood Performance in a Kuwait Heavy Oil Reservoir

Abstract

Abstract The objective of this study is to assess any opportunities to improve field recovery or thermal efficiency by evaluating different steam quality scenarios and their impact on the performance of the cyclic steam stimulation and steam flood in Lower Fars reservoir. In this study, simulation history matching of the dynamic test data from the ongoing thermal pilots was used to validate the static and dynamic description. The process results in an improved dynamic model to be used specifically for the steam quality scenarios evaluation, which was then used in the prediction mode for deciding on an optimum steam quality percentage for the upcoming steam flood operation. Different bottom-hole steam quality scenarios are defined using different steam quality output values at the steam generator and a fixed amount of surface network heat loss. The wellbore heat losses are explicitly modelled to arrive at bottom hole steam quality corresponding to a boiler steam quality. The impact of the steam quality on the cumulative amount of oil produced is significant when an economic steam oil ratio cutoff is applied. There was an overall 40% difference in cumulative oil production between low and high steam quality cases, and a 30% difference when an energy cut off criterion was applied instead of the steam oil ratio cutoff. The highest steam quality resulted in the best performance in terms of oil recovery and energy efficiency. Analysis of the results show that the effect of steam quality is different during different periods of the CSS/SF process and mainly related to the different amount of enthalpy injected. During the CSS period a lower steam quality results in lower oil recovery but at a better efficiency compared to a high steam quality. In the steam flood phase the high steam quality results in both higher recovery and higher energy efficiency. The latter is caused by lower over and underburden heat loss. The bottom hole steam quality is a measure of the energy content of the steam that is delivered to the reservoir. This has a significant impact on the efficiency of the thermal recovery process. The steam quality can vary as function of well location and time for numerous reasons. Thus, it is essential to understand how these variables affect the recovery process.