THE STUDY OF HYSTERESIS EFFECT ON WAG INJECTION

Evaluation of hydrocarbon recovery processes are always faced with more difficult complexities with regards to fluid displacement. These complexities are brought forth by a phenomenon called hysteresis, whereby certain dynamic rock properties and their flow are dictated upon by rock-fluid interaction. In these interactions, three-phase relative permeabilities and capillary pressure exhibit strong dependence on the saturation path and saturation history. Such dependence is characterized by a sequence of three-phase drainage and imbibitions processes which are especially relevant in immiscible water-alternating-gas (WAG) processes.
This paper investigate the impact of using history dependent saturation functions in reservoir simulation on water-alternating gas (WAG) injection, an Enhanced Oil Recovery (EOR) method, aimed at improving sweep and displacement efficiencies. In this work, the author identified the available hysteresis model in the literature that will be used in simulation by applying the experimental data obtained in the literature
A comparison of the simulation results using the hysteresis model and actual field performance data in the literatures is later evaluated as well as the methodology adopted.
Generally the results show that the impact of using three phase relative permeability and hysteresis is significant on the performance of the WAG injection, which must therefore, be considered in the evaluation of the WAG scenario in any field application. Also in this procedure, applying WAG injection with hysteresis effect and residual oil reduction due to gas trapping, the sweep efficiency can improve leading to a better recovery factor.
Keywords: Hysteresis; Drainage and imbibitions; Water-alternating-gas; Three phase flow; residual oil.