Recovery of Oil in Limestone with Cationic Surfactant: Investigation of the Adsorption, Wettability, and Spontaneous Imbibition

The performance of petroleum recovery methods is dependent on the characteristics of the reservoir rock, oil quality, and formation water. One fundamental feature for considering petroleum recovery methods is the wettability of the rock reservoir. Also, this feature impacts the displacement of fluids in the rock reservior. In the case of the limestone, which normally features oil wettability, enhanced recovery methods are responsible for altering surface wettability. In this study, the effect of concentration of a cationic surfactant in the oil recovery from limestone is shown. In these tests, finite-bath technique was used to investigate adsorption by varying the amount of adsorbent and contact time. By carrying out contact angle assays, the wettability of the limestone was assessed. In addition, the oil recovery was effected by spontaneous imbibition. In this study, the limestone samples with solutions of CTAB in the concentrations of 0.8596 g/L and 1.2280 g/L, using a 2% KCl solution are treated. The results showed enhanced adsorption of CTAB at the CMC. The nature of this phenomenon did not induce changes in the wettability of the rock, which was confirmed by the contact angle measurements. In the spontaneous imbibition, more oil could be recovered when using a CTAB below the CMC, possibly due to less intense adsorption by the limestone.