A statistical approach to investigate oil displacement efficiency in thermal recovery techniques for heavy oil based on one-dimensional core experiment

摘要

Precise description of displacement efficiency (Ed) is extremely important for evaluating the performance, economic effectiveness and final recovery of thermal recovery techniques. Current researches mainly focused on one-dimensional core displacement experiment, and it is difficult to obtain precise Ed beyond the range of test points. In addition, there are two ways to improve the Ed for thermal flooding: Increasing injection pore volume (PV) or raising injection temperature (T), it's hard to make decisions. In this study, the above two problems were solved by a statistical approach research. At the beginning, one dimensional core displacement experiment was carried out for hot water and steam, respectively. Then, dozens of curves and correlations about Ed varied with injection PV number and injection temperature was regressed, respectively. Based on this, the formula of Ed and PV, Ed and T for injection hot water and steam was established respectively, which makes up for the shortage of the finite test data points. Next, chart of the Ed between the PV and T was obtained. In addition, sensitivity analyses of injection rate and steam quality are discussed in this paper. Finally, the precise of the regression formula was verified by three steam flooding case of different heavy oil fields. The results indicated that, in order to get higher Ed, higher injection PV and temperature are beneficial. With the Ed chart, technicians can determine different schemes to improve oil displacement efficiency according to specific reservoir conditions. Besides, main production indexes such as oil recovery can be predicted quickly and precisely.