Implementing New Microemulsion Systems in Wettability Inversion and Oil Recovery from Carbonate Reservoirs

Large investments in exploratory activities have stimulated new oil discoveries, generally in carbonate reservoirs. These reservoirs tend to be oil-wet, an aspect that impairs the mobilization of oil in the reservoir. However, different methods can be used to displace the oil. In particular, the wettability of the reservoir surface can be inverted to facilitate oil flow, thereby improving production rates. This paper aims to examine the influence of the inversion of rock wettability in the production and oil recovery from carbonate reservoirs using microemulsion systems. The study involved the use of three surfactants: a cationic one (CTAB), an anionic one (SDS), and a nonionic one (UNT90). Phase diagrams were constructed and microemulsion systems with specific compositions were tested in enhanced petroleum recovery assays. The results showed that CTAB presented a higher inversion potential of wettability when compared to the other surfactants. The microemulsions were effective in the recovery of the residual petroleum “in place” obtaining 76.92% for CTAB, 67.42% for SDS, and 66.30% for UNT90 systems.