A Study of Multiphase Flow in CO2-EOR: Impacts of Three-Phase Relative Permeability and Hysteresis Models

Abstract

Multiphase flow in geological CO₂ sequestration (GCS) is fundamental to CO₂ migration and storage. Due to the presence of the oil phase (or non-aqueous liquid phase), GCS with enhanced oil recovery (CO₂-EOR) includes complex multiphase flow processes compared to GCS in deep saline aquifers (no hydrocarbons). Two of the most important factors are relative permeability and associated hysteresis effects, both of which are difficult to measure and are usually represented by empirical interpolation models. This study aims to quantify the impacts of different three-phase relative permeability models and hysteresis models on CO₂ sequestration simulation results. Investigated options of three-phase relative permeability models include the Stone I and Stone II models, a saturation-based weighted segregated model, and a linear model. Studied hysteresis models include a three-phase water-alternating-gas (WAG) hysteresis model, the Carson model, and the Land model. We chose the SACROC unit, an active CO₂-EOR site located in western Texas, as a case study. Simulation results of forecasted CO2 storage suggest that (1) the choice of three-phase relative permeability model and hysteresis model have noticeable impacts on CO₂ sequestration simulation results; (2) impacts of three-phase relative permeability models and hysteresis models on CO₂ trapping are sensitive to different stages of simulation period, i.e., during and after CO₂ injection; and (3) the specific choice of hysteresis model is more important relative to the choice of three-phase relative permeability model.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018