Transport behavior of nanoparticles (NP) in Berea sandstone rock and the determining the EOR potential

Abstract

Utilization of silica nanofluid is a promising technology for the petroleum industry. Specific interest is focused on potential application of nanoparticles (NP) for enhanced oil recovery (EOR). NP interactions in the porous media include the processes of reversible and irreversible adsorption / retention, interaction with rock minerals and fluids. The first part of this work focused on characterizing and studying the NP at elevated salinity and temperature. To investigate the interaction of silica NP with minerals, the next stage of the project addressed the static adsorption of NP on three minerals: quartz, kaolinite, calcite in deionized water and high salinity conditions (synthetic sea water, SSW). Thereafter, single phase core flood experiments were conducted with Berea sandstone at ambient temperature to address transport behavior of silica NP, evaluate dynamic adsorption / retention and study their interactions with rock surfaces. Scanning electron microscopy (SEM) was performed to visualize the adsorption of silica NP on Berea sandstone. Finally, primary recovery floods at elevated temperature with two brine types (low salinity water and SSW) followed by secondary recovery with injection of nanofluid were conducted. Characterization of nanofluids showed that the silica NP were stable at elevated temperature and salinity. Static adsorption experiments showed that NP have higher affinity for adsorption on calcite followed by quartz and kaolinite. It was also observed that adsorption process was enhanced by salinity. Dynamic adsorption of NP in Berea sandstone investigated by single phase core floods showed significant irreversible adsorption / retention of NP and associated increase in sweep efficiency. SEM imaging also showed preferential adsorption of silica NP on quartz mineral. It was also observed that silica NP were well distributed on the rock surface. Finally, oil recovery experiments performed with nanofluid indicated the potential of using silica NP for EOR. It was observed that injection of nanofluid suppresses the mineral reactions in Berea sandstone responsible for raising pH and potassium release. The injection of nanofluid also suppresses the dissolution of cementing mineral calcite. Preparation of nanofluid in SSW enhanced the retention of NP in Berea sandstone.