Effect of small-scale heterogeneity on biopolymer performance in carbonates

Emad W Al-Shalabi

doi:10.1007/s13202-020-00949-7

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.

Highlights

Introduction and backgroundA large fraction of original oil in place (OOIP) remains trapped in the reservoir after both primary and secondary recoveries
The performance of Schizophyllan biopolymer in carbonates with high temperature, high salinity, and low permeability conditions was successfully evaluated at core-scale
Small-scale heterogeneity of the core is important in history matching formation water corefloods as well as in modeling polymer properties, the shear effect on polymer viscosity

Summary

Introduction

Introduction and backgroundA large fraction of original oil in place (OOIP) remains trapped in the reservoir after both primary and secondary recoveries. Fractional flow and mobility ratio analyses give an indication about the performance of the polymer flooding technique; capillary pressure and heterogeneity effects are not captured.

Results

Conclusion