Numerical Simulation of Cyclic Steam Stimulation with Horizontal Well in Heavy Oil Reservoirs

Cyclic steam stimulation (CSS) is currently one of the most widely used technologies for recovering heavy oil. The CSS with horizontal well shows the advantage of the reduction in directional drilling costs, an increase in seepage area and the improvement of sweep efficiency. In this study, based on the actual field data, a CSS numerical thermal simulation model with horizontal well in heavy oil reservoirs was developed by CMG-STARS (version 2017). The production performance of the CSS was predicted, and the main mechanism dominating the CSS process was investigated. Sensitivity analysis of steam operational parameters was performed, thereby obtaining the optimal steam injection strategy of the CSS. The results show that the CSS creates a cylindrically shaped steam chamber around the horizontal wellbore. The main mechanisms presented in oil recovery by CSS are viscosity reduction by temperature increase. CSS with horizontal well can effectively enhance heavy oil recovery. The ultimate oil recovery factor is 2.59% of the original oil in place. The soaking duration of three days can be considered the optimal value, but it has little impact on the oil recovery factor. The optimum steam quality seems to be 0.8. The oil recovery factor increases first and then decreases as the steam injection pressure improves. The oil RF increases with the improvement of the steam injection rate. The findings of this research could provide a reference for the development plan design, production performance prediction, and operation parameter optimization of CSS with horizontal well in heavy oil fields.