EFFECT OF ADDITION OF ANIONIC SURFACTANT ALKYL ETHOXY CARBOXYLATE ON THE WETTABILITY OF (SYNTHETIC) SANDSTONES CONTAINING CLAY MINERALS

• Main Author: Herawati, Ira
• Format: Dissertations
• Language: Indonesia
• Subjects: Pertambangan dan operasi berkaitan
• Online Access: https://digilib.itb.ac.id/gdl/view/70036
• Institution: Institut Teknologi Bandung

Along with the increasing number of mature/relatively mature fields in Indonesia, the application of surfactant injection (as an alternative to the EOR technique) is important to mobilize the remaining oil. The presence of Clay in the sandstone causes the polar component in the oil to be adsorbed on the rock surface, causing a tendency towards oil-wet. The remaining oil potential which is the target of the surfactant injection is greater in the oil-wet resevoir than in the water-wet reservoir. Therefore, surfactant that changes the surface properties from oil-wet to water-wet is required, in addition to the ability of the surfactant to reduce oil-water IFT. Previous researches have shown that different anionic surfactants have different adsorption rates on mineral clays. Furthermore, many literatures have presented that anionic surfactants have little effect in changing the wettability of rocks containing clay minerals compared to cationic and nonionic surfactant. Mainly their experiments used anionic surfactant ethoxylated sulfonate, alkyl benzene sulfonates, sodium dodecyl sulfate, and sodium laureth sulfate. This paper studies the adsorption and its effect of an anionic surfactant alky ethoxy carboxylate (which is almost never discussed) on the wettability of sandstone containing Ca-montmorillonite and kaolinite clays. The effect of wettability on the alkyl ethoxy carboxylate (AEC) injection in an Enhanced Oil Recovery are also investigated. Some experimental works were conducted to support the analysis that include measurements of contact angle, zeta potential, pH, High-Performance Liquid Chromatography analysis, Cation exchange, core flooding and SEM-EDX analysis. The results show that sandstones containing kaolinite clay tend to oil-wet and those containing Ca-montmorillonite clay tend to water-wet. The interaction of sandstones containing Ca-montmorillonite clay indicates a cation exchange mechanism occurs where the cation exchange caused by the addition of anionic surfactants alkyl ethoxy carboxylate (AEC) is lower than the interaction with brine. The cation exchange that occurs in sandstones containing kaolinite clay is very small in value, especially for the addition of AEC surfactant with a concentration of 2wt%. The AECa dsorption that occurs in sandstones containing Ca-montmorillonite and kaolinite clay forms a parabolic curve trend with the minimum at about 15% concentration. The adsorption of AEC was higher by Ca-montmorillonite. Meanwhile, the greater wettability alteration by AEC occurs in sandstone containing kaolinite clay. The relationship between surfactant adsorption and contact angle is inverse, where the higher the surfactant adsorption, the smaller the contact angle value, and vice versa. The order of oil wettability increases in the following order: sandstone containing montmorillonite, sandstone with no clay, and sandstone containing kaolinite. In core flooding experiments, the waterflood cumulative oil recovery of a sandstone containing kaolinite clay show the least compared to those of sandstone with no clay and sandstone containing montmorillonite, which is highly affected by the wettability. The higher oil wettability the lower oil recovery by waterflooding. The surfactant AEC lower the IFT brine-oil from 5 dyne/cm to 3x10-2 dyne/cm. In all cases in this work, the AEC reduces contact angle where the change of contact angle occurs higher in sandstone containing kaolinite clay, followed by sandstone with no-clay and sandstones containing montmorillonite. It shows in core flooding experiment where higher incremental oil recovery by AEC 1% occurs in sandstones containing kaolinite clay followed by sandstones with no-clay and sandstones containing montmorillonite clay.