Evaluation of new surfactants for enhanced oil recovery applications in high-temperature reservoirs

Abstract

Surfactants have been successfully used for enhanced or improved oil recovery in reservoirs having mild conditions (low temperature, low salinity). Reservoirs having harsh conditions, however, offer unique challenges in that most surfactants precipitate and chemically degrade due to a combined effect of high temperature and hardness salinity. Industry's efforts are continuing to develop or formulate surfactants for oil recovery applications to high temperature and salinity. The aim of this study was to evaluate several modified anionic surfactants/formulations that were claimed to be able to overcome the unfavorably high-salinity brine (sea water) and high temperature and to understand the impact of high temperature to surfactant adsorption. A series of experiments were conducted to characterize and quantify the effects of aging time in high temperature (106 °C) and seawater salinity (32,000 ppm with 1600 hardness) on surfactant performance. Results for both sulfate-and sulfonate-based surfactants were deemed not to be satisfactory. Sulfate-based surfactants encountered hydrolysis problem at high temperature, whereas sulfonate-based surfactants precipitated in the presence of divalent ions. This study then focused on alkyl ether carboxylate (AEC) as the main surfactant, and blends of AEC with alkyl polyglucoside (APG). To find the optimum conditions, phase behavior tests were performed with a fixed seawater salinity but with different blending ratios of surfactant and co-surfactant, as well as overall surfactant concentrations, similar to the salinity scan. Type III microemulsion was observed for both surfactant solutions of AEC and AEC-APG blend with IFT of 10 −3 mN/m (millinewton/meter). Surfactant adsorption resulted in lower adsorption in the high-temperature region. The results of this project are urgently needed by the industry for future screening in order to find suitable surfactants for applying to reservoirs with harsh conditions. The study also intends to provide an understanding of adsorption relationship to high temperature, as a guideline in addressing surfactant losses due to adsorption at high-temperature field application.

High-Performance Polymeric Surfactant of Sodium Lignosulfonate-Polyethylene Glycol 4000 (SLS-PEG) for Enhanced Oil Recovery (EOR) Process

“…The negative charge comes from the sulfonate (−SO 3 − ) [28][29][30] and its salt (NaSO 3 ) [14] as the hydrophilic groups. However, sulfonate-type surfactants precipitate in the brine solution in which divalent ions are present because they are sensitive to divalent ions [8].…”

“…9, the type of microemulsion obtained is the Windsor Type I microemulsion. According to Zulkifli et al [8], the best microemulsion type for EOR process purposes is Winsor Type III, followed by Winsor Type I, and the last is Winsor Type II. Winsor Type I microemulsion can also be mentioned as Winsor Type II(−) or lower-phase microemulsion, which is the minimum type of microemulsion for EOR process purposes [35,36].…”

“…According to Zulkifli et al [8], the best microemulsion type for EOR process purposes is Winsor Type III, followed by Winsor Type I, and the last is Winsor Type II. However, Winsor Type I microemulsion can be changed to Winsor Type III microemulsion by changing several parameters, such as the concentration of surfactant, salinity of the brine used, and so on [8]. Polymeric surfactant is very attractive to the EOR method.…”

“…Teng et al [19] reported that SLS has a water-soluble characteristic. However, sulfonate-type surfactants precipitate in the brine solution in which divalent ions are present because they are sensitive to divalent ions [8]. On the other hand, polyethylene glycol (PEG) is a polymer that has high hydrophilicity [6].…”

Modified Two‐Phase Titration Methods to Quantify Surfactant Concentrations in Chemical‐Enhanced Oil Recovery Applications

“…Surfactants have been used in petroleum industry for many decades (Al Batal et al, 2019; Bhardwaj and Hartland, 1993; Johnson, 1957; Negin et al, 2017; Quintero, 2002; Zhou et al, 2019). Surfactants are surface‐active agents with multiple functionalities beneficial to the upstream petroleum industry (Ahmadi et al, 2012; Hirasaki et al, 2011; Pal et al, 2019; Zulkifli et al, 2020). Surfactants lower interfacial tension (IFT) between fluids, which is very important in operations ranging from drilling to enhanced oil recovery (EOR) applications.…”