An experimental approach to low cost, high-performance surfactant flooding.

Abstract

Surfactant flooding plays a key role in chemical enhanced oil recovery due to its ability to reduce interfacial tension between the aqueous and oleic phases, thereby mobilizing the trapped oil droplets into a flowing oil bank which invariably reduces the amount of residual oil saturation thus accounting for additional oil recovery of about 20%. However, the cost of surfactant chemicals has made surfactant flooding less attractive. Interestingly, recent experimental studies have reported that certain local materials capable of acting as surface active agents can effectively recover residual oil. This has attracted more interest due to their low cost, availability and eco- friendly nature. This paper reviews the oil displacement efficiency of different local surfactants in comparison with synthetic surfactant. Commonly used synthetic surfactant, Sodium dodecyl sulphate (SDS) and three different local surfactants namely AlkaSurf X (a hibiscus plant extract), Palm kernel oil (Elaeis guineensis) and Moringa leaf (Moringa oleifera) was evaluated in the laboratory using various concentration in a bid to compare their performance, however only two local surfactants; Moringa leaf (Moringa oleifera) and AlkaSurf X were used as the third surfactant failed the initial compatibility test. To simulate actual formation brine, brine samples were prepared in the laboratory using sodium chloride and potassium chloride with Total dissolved solids (TDS) of 30,000 ppm. Critical micelle concentration (CMC) was calculated to ascertain the right concentration to flood with. Sandstone oil displacement experiments using core plugs with porosity values ranging from 22%-23% was carried out on medium crude oil to ascertain the effectiveness of the selected local surfactants in recovering oil. Results showed high compatibility of the brine with all the selected local surfactants. As the brine salinity increased, the pH of the surfactant concentration increased. In line with the results obtained from the CMC plot, the synthetic surfactant performed best at 0.2 wt.% while the local surfactants performed best at a higher concentration of 0.4 wt%. Of the two local surfactants, AlkaSurf X gave the highest additional recovery of 22.7% OOIP while the synthetic surfactant gave an additional recovery of 20% OOIP. This study underpins the oil displacement efficiency of these local surfactants. Moreover, Alkasurf X can be considered as a novel, low-cost, high performing surfactant capable of enhancing oil recovery.