Generalised model for simulation of two- and three-phase cycle-dependent hysteresis in sandstones

Abstract

Many Enhanced Oil Recovery (EOR) processes involve injecting multiple slugs to improve the volumetric sweep efficiency in the reservoir, such as Water-Alternating-Gas (WAG), polymer flood, surfactant flood, and steam injection. Precise estimations of hysteresis phenomenon in relative permeability (kr) and capillary pressure (Pc) plays a crucial role in conducting accurate prognosis of oil production, reliable decision making, and feasibility assessment of EOR plans. Over the years, abundant high-quality experimental data revealed limitations of existing hysteresis models in the literature and highlighted the necessity of introducing a reliable hysteresis model.This paper presents a new hysteresis model for accurate estimation of ultimate oil recovery and pressure drop in coreflood experiments. In contrast to the existing models, all required parameters are directly calculated from experimental data, eliminating the tuning procedure, and reducing the associated uncertainties. This study also includes a detailed discussion of estimating trapped gas saturation and application of Land’s trapping model in cyclic systems, considering their importance in CO2 sequestration and non-aqueous contaminant flow in soil. The presented model also benefits from a new procedure for estimating final saturations during a WAG experiment based on common observations of WAG experiments. A comprehensive set of cyclic two- and three-phase experiments performed on a homogenous sandstone over a wide range of injection scenarios, fluid, and rock properties were successfully used to validate the model. The detailed analysis and comparison of various cyclic experiments herein provide an excellent benchmark for future validation and development of hysteresis models.