A Study on the Low Salinity Waterflooding (LSW) in a Part of a Depleted Oilfield of Upper Assam Basin

Abstract

Maximizing the hydrocarbon recovery from depleted oilfields is the biggest challenge now a days which becomes an opportunity for advanced EOR technologies. One of such EOR technology that can promote the oil recovery efficiency from such fields is the low salinity waterfloofing (LSW) which gains the attention of many researchers due to its easiness to use implications, less cost and environment-friendly nature. Different studies have shown that fines migration, pH increase, electrical double layer (EDL) expansion and multicomponent ion exchange (MIE) mechanisms have important role in law sal effect (LSE) based on which the present study has been made. Hughes et al. and Lager observed that, the presence of calcium ion in formation brine, polar organic components (resin and asphaltene) in crude oil and kaolinite in the reservoir rock all have important role in the above mechanisms and thereby to improve recovery by modifying the rock wettability. Again, smectite, kaolinite and illite clay minerals contribute to the LSE by causing a local increase in pH in the vicinity of the clay surfaces which in turn modify the reservoir rock wettability. The present study shows the presence of resin and asphaltene in crude oil, calcium and magnesium ion in formation brine and smectite, kaolinite and illite in the reservoir rock of the study area which have important role in improving oil recovery during LSW.

Keywords: EOR, LSE, EDL, MIE, wettability, resin, asphaltene, basin