Impact of hysteresis of relative phase permeabilities in 3D modeling of cyclic waterflooding in a carbonate reservoir

The main task when extracting oil from waterflooded reservoirs during late development stages is enhancing the mobility of the remaining reserves. In the context of declining oil export prices, the use of chemical and gas methods for enhancing oil recovery in mature fields is becoming increasingly unprofitable, given their associated technological and economic risks. To improve the efficiency of mature oilfield development, non-stationary (cyclic) waterflooding is an alternative to tertiary methods for enhancing oil recovery. The primary benefit of cyclic waterflooding is its simplicity of implementation and minimal extra costs, which have made this method very appealing in today's market conditions. The relevance of cyclic flooding within the context of this study is underpinned by the prevalence of mature fields in the region, including the asset under investigation. This article presents approaches for planning cyclic waterflooding, using an example of a complex carbonate reservoir from the Tournaisian stage (C₁t) oilfield of the Perm Krai, Russia. The novelty of this research lies in the presented laboratory-based studies of the hysteresis of relative phase permeabilities (HRPPs) in “water-oil” systems, which are then used to assess the effectiveness of cyclic waterflooding technology on an updated 3D hydrodynamic model via tNavigator software. Results from the multivariate calculations for cyclic waterflooding are presented, both with and without considering HRPP. The importance of incorporating models with inverse hysteresis loops into commercial simulators for carbonate porous media with mixed types of rock wettability is demonstrated and justified, and directions for future research are proposed. These findings emphasize the need for laboratory studies of carbonate reservoirs in imbibition and drainage modes to constrain the real reservoir processes occurring during cyclic waterflooding.