Laboratory Study of Alkyl Ether Sulfonates for Improved Oil Recovery in High-Salinity Carbonate Reservoirs: A Case Study

Abstract

Yibal oil reservoir, a fractured carbonate formation located in the north of Oman and characterized by high salinity brine and high temperatures, is a potential candidate for enhanced oil recovery (EOR) projects. This experimental study focused on the possibility to use surfactant injection as an EOR process in the Yiabl field. On the basis of the results from our previous investigations, ethoxylated sulfonates and amphoteric surfactants were used in this study. Selected surfactants showed a great tolerance to high salinity and temperatures. All surfactant systems displayed dynamic interfacial tension (IFT) behavior, in which transient ultra-low IFTs were detected. Dilute surfactant solutions (0.1 wt %) were considered for core-flooding tests on limestone plugs. In one set of experiments, surfactant solutions were injected into a fully water-flooded core (surfactant tertiary recovery). In another set, surfactant solutions were injected without pre-water-flooding (surfactant-modified water-flooding or surfactant secondary recovery). Results of tertiary recovery were found to be between 1 and 7% of original oil in place (OOIP), which correspond to 6 and 24% of residual oil in place (percentage based on the remaining oil in place after water-flooding). Tertiary surfactant injection therefore appears to be an attractive option for pre-water-flooded zones for additional oil recovery. In the other hand, results of secondary recovery for some surfactants showed significant oil recovery compared to water-flooding, whereas for other surfactants, water-flooding was more effective. Secondary surfactant recovery resulted in faster rate recovery as compared to water-flooding. Thus, minimum pore volume (PV) injected at ultimate oil recovery for 7-58 surfactant was found to be significantly lower (2.3 PV) than the corresponding PV in water-flooding (9.1 PV).

Screening of amphoteric and anionic surfactants for cEOR applications using a novel approach

“…This equilibrium IFT value is reported for all formulations at various conditions. The dynamic IFT behavior of some surfactants has been reported in many previous studies [2,[29][30][31][32][33].…”

“…For all investigated surfactant concentrations, IFT gradually increased with increasing temperature from 30 • C to 70 • C. Different observations were reported on the effect of temperature on IFT. Aoudia et al [2] reported an increase in the IFT with the increase in temperature. Wu et al [29] observed a decrease in the IFT with temperature using Alfoterra surfactant for n-decane/water system.…”

“…Chemical enhanced oil recovery (cEOR) is one of the techniques employed to oil reservoirs to recover the remaining oil which cannot be recovered by primary recovery. A number of chemical flooding methods were reported in the literature, such as surfactant [2][3][4][5], polymer [6][7][8], alkali [9], surfactant/polymer [10][11][12][13] and alkali/surfactant/polymer [14,15]. Chemical methods are utilized to increase the viscosity of displacing fluid for better mobility control, to increase the sweep efficiency and to reduce the interfacial tension (IFT) between water and crude oil.…”

Effect of different families (imidazolium and pyridinium) of ionic liquids-based surfactants on interfacial tension of water/crude oil system

“…A detailed description of the used spinning drop method has been brought elsewhere [28,29]. The IL solution as outer-phase was injected into the glass tube, and 3-4 L crude oil as inner-phase was put into the middle of the tube.…”

Use of petroleum sulfonates to obtain an alkali-free flooding system ensuring ultra-low interfacial tension

“…Many surfactants have been proposed as oil displacement agents: ethoxylated and propoxylated sulfates [1], internal olefin sulfonates [2], alkyl ether sulfonates [3], betaine amphoteric surfactants [4], petroleum sulfonates [5], alkyl polyglucoside [6] etc. Petroleum sulfonates are the most widely available and the most inexpensive [7].…”