Characterization of a biopolymer produced by Arthrobacter viscosus cect 908 for application in microbial enhanced oil recovery

Abstract

Polymer-flooding is one of the most promising techniques used to increase the productivity of mature oil reservoirs. Polymers reduce the mobility ratio of the injected water relative to the crude oil, improving the displacement of the entrapped oil and, consequently, increasing oil recovery. Biopolymers such as xanthan gum have emerged as eco-friendly alternatives to the chemical polymers commonly used by the oil industry. However, in order to seek for more efficient biomolecules, alternative biopolymers must be studied. In the present work, the biopolymer produced by Arthrobacter viscosus CECT 908 was studied for the first time for a possible application in Microbial Enhanced Oil Recovery (MEOR). The rheological properties of this biopolymer were studied and compared with those of xanthan gum. The results demonstrated that the biopolymer produced by A. viscosus CECT 908 exhibited higher viscosity values (1207 ± 14 mPa.s at a concentration of 2.5 g/L, 40°C and a shear rate of 1.4 s1) when compared with xanthan gum at the same conditions (281 ± 11 mPa.s). The structure of the biopolymer was not affected by high shear rates (up to 300 s1), which is important for its application in enhanced oil recovery processes. Furthermore, it remained stable after exposure at high temperatures (up to 80°C) and salinities (up to 200 g NaCl/L), making it useful for application in a wide range of oil reservoirs. In sand-pack column assays performed using a heavy crude oil (40°C= 167 mPa.s) this biopolymer allowed a higher additional oil recovery (25.7 ± 0.5%) when compared with xanthan gum (19.8 ± 1.2%) due to the achievement of a more favorable mobility ratio between the injected biopolymer solution and the crude oil, which resulted in a more uniform displacement front. The results herein obtained demonstrated, for the first time, that the biopolymer produced by A. viscosus CECT 908 is a promising agent for enhancing heavy oil recovery in high temperature and high salinity oil reservoirs. Copyright 2018, Society of Petroleum Engineers.