Wettability-Based Retention of Encapsulated Petroleum Sulfonate in Carbonate Rocks at High-Temperature and High-Salinity Conditions

Abstract

Understanding retention of chemicals onto the rock surface with varying wettabilities allows for better understanding of behavior and performance of the chemicals for applications in oil-bearing rocks. This work studied dynamic retention properties of the low-cost encapsulated petroleum sulfonate nanofluid–Nano-Surfactant (NS)–to the Indiana limestone outcrop surfaces at various wettabilities and surface chemistry while under high-temperature and high-salinity (HTHS) reservoir conditions. Different wettabilities and surface chemistry of the Indiana limestone outcrops were achieved through chemical functionalization utilizing silane coupling agents (4-phenylbutyltrimethoxysilane, n-decyltrimethoxysilane, and 9-phenanthrenyltriethoxysilane), and the NS transport in those core plugs was studied via dynamic core flooding. Incorporating 4-phenylbutyl and n-decyl functional groups onto mineral surfaces made the porous media less water-wet but did not change the transport performance of the NS when compared to the water-wet (untreated) core plugs. In comparison, the propagation of the NS was slightly delayed in the porous medium covered by 9-phenanthrenyl groups, and retention increased from 0.69 to 0.72 mg/g. Results suggested that transport of the NSs was not impacted by variation in surface wettability and that polyaromatic groups on the rock surface were the primary contributor to the increased interaction between the NS and the carbonate minerals.