Characterization of water-containing reservoir oil using an EOS for steam injection processes

Abstract

Experimental results in the literature indicate that the water solubility in the oleic (L) phase (xwL) can be high at reservoir conditions in thermal oil recovery processes. However, the effect of xwL on oil recovery has not been fully understood, especially for steam-assisted gravity drainage (SAGD) for in-situ bitumen recovery. This research presents a framework for reliable characterization of water/reservoir–oil mixtures for numerical simulation of steam injection processes. The Peng–Robinson equation of state (PR EOS) is used with the van der Waals mixing rules.A new correlation is developed for binary interaction parameters (BIPs) for water with n-alkanes. Unlike previously proposed BIP values, the new correlation is based on optimization of three-phase predictions for water/n-alkane binaries, including upper critical endpoints (UCEPs). In the characterization method proposed for water-containing reservoir oil, the developed correlation serves as the well-defined upper limit for BIPs of water with hydrocarbon components. A SAGD simulation case study for Athabasca bitumen shows that bitumen recovery can be substantially affected by xwL through the L-phase mobility. The characterization method developed in this research can be used with at least one measured xwL value for a reliable phase-behavior model for steam injection simulation.