Universidade Federal do ABC, Brazil
Sergio Brochsztain has completed his PhD from Tel-Aviv University, Israel, and postdoctoral studies from Sao Paulo University, Brazil. He is presently Associated Professor at Federal University of ABC, in Sao Paulo State, Brazil. He has published more than 35 papers in reputed journals
Cyclodextrins (CDs) are cyclic oligosaccharides with important applications in the pharmaceutical and food industry. In the present work, the CDs were evaluated as potential agents for enhanced petroleum recovery. For this purpose, the contact angle () of a hydrocarbon drop (dodecane) on a quartz surface was measured, with the system immersed in an aqueous NaCl solution, containing or not the CD. Here, the dodecane, the quartz and the NaCl solution represent the oil, the rock surface and the reservoir brine, respectively, thus mimicking the situation occurring in actual oil reservoirs. Two different surfaces were tested: native quartz (hydrophilic) and quartz functionalized with octadecyltrichlorosilane (OTS), rendering the surface hydrophobic. The latter arrangement intends to be a mimetic system for rock surfaces covered with asphaltenes, a situation usually found in reservoirs. When native quartz was employed, it was found that the presence of the CDs increased only slightly the oil–water contact angle (as measured through the hydrocarbon drop). Striking results were obtained, however, with the OTS-modified quartz. In this case, the dodecane did not form drops at all in the absence of CDs, but rather spread on the hydrophobic surface ( = 0). In the presence of CDs, on the other hand, well-formed drops were observed, with varying between 80 – 120 degrees (depending on the CD derivative). Thus, the CDs increased the contact angle by a great amount on the hydrophobic surface, showing their potential for detaching the petroleum from asphaltene covered rock surfaces.