Laboratory screening of effective cross-linked polymers to improve the efficiency of oil recovery at carbonate deposits with high mineralization of reservoir water

Abstract

© 2019, International Multidisciplinary Scientific Geoconference. All rights reserved. This work presents laboratory experiments for the development and testing of methods for the selection of the cross-linked polymer for one fractured carbonate reservoir with high salinity (about 220 g/L). For this carbonate reservoir, the applicable industrial polymers are very limited because they cannot effectively increase the viscosity under such a high salinity. Therefore, a crosslinked polymer gel was proposed for enhanced oil recovery in this reservoir. For choosing the most suitable cross-linked polymer for pilot injection, a series of laboratory studies for primary screening was conducted, including solubility evaluation under different water mineralization, determination of the rheological parameters, assessment of long-term stability, the effect of the concentration of cross-linker. After primary evaluation, the most perspective polymer compositions were used for flooding tests on the core samples. On the basis of a large complex of laboratory studies, a workflow has been developed for selecting the optimal polymer and the concentration of cross-linker. The effectiveness of the best polymer was confirmed by filtration experiments. The data obtained from flooding experiments show that the selected polymer effectively reduced the mobility of water in high permeability zones, which allows for displacing oil from zones with low permeability. The results obtained for new polymer are promising for the optimization of the field development efficiency and can be used for further application of the technology in the field to enhance oil recovery. Based on the developed workflow of laboratory experiments, a new cross-linked polymer gel was developed, which shows high efficiency in the case of a carbonate reservoir with high salinity.