Upscaling Study of Vapor Extraction Process Through Numerical Simulation

Vapor extraction (VAPEX) is a process to recover heavy oil by injecting vaporized solvent into a reservoir. Reliable prediction of VAPEX performance is crucial to ensure successful commercial application of VAPEX process. The current practice for VAPEX performance prediction is using analytical scale-up methods which translate the laboratory result to field application. However, the drawbacks associated with the analytical scale-up methods are they only consider about the single phase flow and gravity drainage, and cannot take reservoir heterogeneity into account, which limit the application for the real field cases. In this study, an effort was made to investigate the capability of predicting up-scaled VAPEX performance through numerical simulation method. 2D test was conducted under the same conditions as those for the 3D test, and a numerical model was established to simulate the 2D test. History match of the 2D test was conducted by tuning the uncertainties such as relative permeability and capillary pressure. Then the tuned parameters were applied to predict the 3D test performance. Through comparison of the predicted and experimental results in the 3D test, the capability of predicting up-scaled VAPEX processes through numerical simulation was examined. The results show that numerical simulation, compared to analytical method, has more potential to be used as scale-up method because of the improved prediction results. The initial waterflooding performance can be successfully predicted, whereas the uncertainty in upscaling the VAPEX process is large. The difference between the predicted and measured oil recovery factors was in the range of 0.75-25.14%, depending on the different combinations of uncertain parameters.