Alkaline Surfactant Polymer Flooding using a Novel Class of Large Hydrophobe Surfactants

Abstract

Abstract With recent advances in Alkaline-Surfactant-Polymer (ASP) flooding, the demand for high performance EOR surfactants is rapidly increasing. This is accompanied by the need for a diverse raw material base. We have successfully developed and tested a novel class of hydrophobes for anionic surfactants that satisfy this need at low cost. The hydrophobe for these novel surfactants is Tristyrylphenol (TSP), which is based on the petrochemical feed stocks, phenol and styrene. TSP based surfactants have unique structural features that can be exploited to fit many EOR surfactant needs. We illustrate the performance of this class of TSP surfactants for a waxy crude oil with a high acid number. Selecting a formulation proved difficult due to the high molecular weight of the crude. The TSP surfactant has four benzene rings that enhanced the solubility of the heavy components of the crude oil, including asphaltenes, making it an attractive choice. The dead crude oil was diluted with either decalin or cyclohexane to match the equivalent alkane carbon number (EACN) of the live crude oil. The TSP alkoxy sulfate molecules with varying lengths of propoxy (PO) and ethoxy (EO) chains were tested in microemulsion phase behavior experiments in order to obtain ultra-low IFT at optimum salinity with low microemulsion viscosities. The ASP formulation was successfully tested in reservoir core floods using both surrogate oil and live oil.