Effect of small-scale heterogeneity on biopolymer performance in carbonates
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ORIGINAL PAPER-PRODUCTION ENGINEERING
Effect of small‑scale heterogeneity on biopolymer performance in carbonates Emad W. Al‑Shalabi1 Received: 18 January 2020 / Accepted: 30 June 2020 © The Author(s) 2020
Abstract Polymer flooding is a well-established chemical method for enhancing oil recovery in sandstones; however, it has a limited application in carbonates. This is due to the harsh reservoir conditions in carbonates including high temperature, high salinity, and high heterogeneity with low permeability. This paper numerically investigates the effect of Schizophyllan biopolymer on oil recovery from carbonates. The effect of biopolymer on oil recovery was predicted by running several 1D simulations. Biopolymer flow behavior was modeled based on experimental data. The results showed that the effect of the investigated biopolymer on oil recovery was not much pronounced compared to conventional waterflooding. This is due to small-scale heterogeneity, which increased effective shear rate and hence, decreased in-situ polymer viscosity. Formation permeability, polymer viscosity, and oil saturation maps were consistent in justifying this observation. The findings of this study were supported by fractional flow and mobility ratio analyses. This work highlights the importance of small-scale heterogeneity of the core in modeling polymer flooding, particularly the shear effect on polymer viscosity. Keywords Biopolymer modeling · Chemical enhanced oil recovery (CEOR) · Small scale heterogeneity · Mobility ratio · Fractional flow analysis
Introduction and background A large fraction of original oil in place (OOIP) remains trapped in the reservoir after both primary and secondary recoveries. The latter necessitates the need for enhanced oil recovery (EOR) techniques to improve the oil recovery in an economic way under certain market and technology conditions (Lake 1989). Different EOR techniques are being used including solvents, chemical flooding, thermal methods, and others (Al-Shalabi et al. 2015; Al-Shalabi and Sepehrnoori 2016, 2017). Polymer flooding is a widely used chemical EOR technique that has been studied and practiced for many years (Chang 1978). In this technique, polymers are added to the water in order to increase its viscosity and hence, improve water sweep efficiency through decreasing the mobility ratio between the displacing fluid (water) and the displaced fluid * Emad W. Al‑Shalabi [email protected] 1
Petroleum Engineering Department, Khalifa University of Science and Technology, Sas Al Nakhl Campus, Abu Dhabi, United Arab Emirates
(oil). Consequently, this viscous water dampens viscous fingering effects and results in better volumetric sweep efficiency (Sorbie 1991). This paper discusses in particular, the application of “biopolymer” flooding as an EOR technique on oil recovery from “carbonate” reservoirs under “harsh” conditions.
Carbonates under harsh conditions More than half of the world’s hydrocarbon proven reserves are present in carbonate reservoirs. The majority of these reservo
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