Evaluation of continuous surfactant flooding in north east africa: Casestudy of bentiu reservoir

Recently, continuous surfactant flooding (CSF) has been devised as an improvement to overcome thelimitation of conventional surfactant flooding (SF). The utilization of CSF depends on several factors such assurfactant type and reservoir characteristics. This study performs the feasibility study of utilizing CSF for amarginal field of Bentiu reservoir in Sudan with a production history of 20 years. The reservoir is moderatelyheterogeneous reservoir. Thirty-six (36) cores from the natural reservoir extension of its most effective basinwere evaluated. The evaluation focused on the role of core properties such as porosity and permeability onCSF. The comparison of the results was benchmarked by water flooding and the conventional surfactantflooding. Numerical simulation CMG STARS was used to perform the sensitivity analysis on the corescale. The results of the study showed 5 main ranges of the cores available after grouping. The highestrecovery factor of water flooding was in the range of 48 (+/- 1.3%). There were no significant changes inthe cumulative oil produced; however, the core physical properties affected the duration needed to reachthe production plateau. For CSF, the highest recovery was in the fourth group of cores. In term of watercut, the percentages declined slightly with a range of 0.01 to 0.09 % with lowest percentage value water cutrecorded at 99.90% and the highest result of 99.99%. Moreover, the recovery factor reached up to 45.80%using water flooding method and increased up to 90.41 % in CSF method. The remaining oil saturationreached to 0.35 during water flooding and dropped to 0.061 during the CSF. Moreover, the result obtainedin CSF which indicates that the optimum porosity and permeability range of 0.26 to 0.29 in porosity and 390to 2220 mD in permeability is the suitable range to be implemented in continuous surfactant application.Hence, based on the obtained results, CSF shows promising effects for use in marginal oil fields.