Pore-Scale Investigation and Performance Evaluation of SMART LowSal Flooding for Enhanced Oil Recovery from Matured Reservoirs Using a Lab-on-a-Chip
Uma Sankar Behera, Ganesh Kumar, Jitendra S. Sangwai
Abstract
Oil recovery from a matured oilfield is challenging due to the low recovery factor. These challenges became opportunities for existing low-salinity water (LSW)-based enhanced oil recovery (EOR) methods. The performance of the LSW in recovering the residual oil from a matured oilfield is improved with the help of additives, viz., surfactant, water-soluble polymer, and silica nanoparticles (NPs). In the present study, series of experiments have been carried out to understand the pore-scale oil displacement phenomena of the novel nanofluids (SMART LowSal) using a microfluidic chip (lab-on-a-chip) integrated with an inverted microscope. The microfluidic chip is saturated with oil and is flooded with different nanofluids (NFs) to recover oil. The efficacy of oil displacement is evaluated using two unique methods (series and parallel). The oil displacement efficacy from the chip matrix, the interaction between rock–oil–nanofluid, and wettability alteration of the rock representative surface have been visually investigated. The oil displacement results are compared with the oil recovery results from the sand-pack reactor and Amott cell. Oil displacement was found to increase with increasing concentration of nanoparticles in NFs and slightly decreases beyond 1000 ppm of NPs. Visual observation clarified the complex interaction of rock–oil–nanofluid systems. A significant reduction in the interfacial tension of the fluid–fluid phase in the presence of surfactant leads to elongation of the oil globules and higher oil recovery. A thin layer of a film of water is noticed between the grain and the fluid phase, which could be the reason for the wettability alteration and improved oil recovery. The lab-on-a-chip method adopted for evaluating the efficacy of oil recovery due to the various nanofluids could help better understand the displacement phenomena and screening of additives for the best formulation of injection fluid for EOR application.