Abstract
The main objective of this work is to address the adsorption of Silica nanoparticles (NPs) dispersed in different brines on chalk surfaces and their effect on fluid/rock interaction. Isothermal static and dynamic adsorption on chalk are addressed here. Isothermal static adsorption showed increased adsorption of NPs at higher salinity. The tests were performed to cover wide range of injection scenarios with synthetic seawater (SSW) and low salinity water (LSW). The selected LSW composition here is based on 1:10 diluted SSW, which has shown to have superior performance compared to other ion compositions. The dynamic adsorption tests of NPs showed reduction of calcite dissolution of about 30% compared to LSW alone. That is, silica nanofluid hinders calcite dissolution i.e., has less effect on chalk matrix integrity which is a major concern in chalk reservoir, if low salinity is employed for enhanced oil recovery. Both scanning electron microscope images and pressure drop across the core during nanofluid injection indicated no throat blockage. Based on ion tracking and the monitored pH, the mechanism(s) for NP adsorption/desorption are suggested. The results from this study suggests a synergy wherein adding relatively small amount of silica NPs can improve the performance of low salinity floods.
Highlights
Nanofluids (NFs) have recently attracted attention from researchers in different disciplines
We found the silica NPs modifies the sandstones minerals and it can be utilized to overcome the problem of formation damage induced during low salinity flooding in sandstones
The NFs were prepared in deionized water (DIW), low salinity water (LSW) and synthetic seawater (SSW)
Summary
Nanofluids (NFs) have recently attracted attention from researchers in different disciplines. One of their fields of application is enhanced oil recovery (EOR) from petroleum reservoirs [1,2,3,4]. With sizes below 100 nm and high specific surface area, nanoparticles (NPs) are suitable for subsurface porous media applications since they can pass through the pore throats of porous media without blocking them and enhance oil recovery at relatively low volume concentrations [5,6] via wettability alteration [7,8,9]. Adsorption and transport of nanoparticles in porous media is of primary importance for subsurface applications as this determines the effectiveness of the nanofluid injection. Nazari Moghaddam, et al [25]
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