Application of Nanofluids for Altering Wettability in Heavy Oil: A Field Test

Abstract The production of heavy crudes presents a considerable challenge due to several factors. These include complex geology, active aquifers, wells influenced by water injection patterns, reservoirs with mixed wettability tendencies favoring oil (high affinity between heavy crude and the rock minerals in the reservoir), and the intrinsic nature of heavy crude, characterized by its high viscosity. Moreover, artificial lift systems often exhibit low efficiency under high bottomhole pressures, and formation damage can occur during drilling, completion, and production stages. Consequently, an unfavorable mobility ratio of the crude can result in early water breakthrough in the wells. Nanotechnology, in the form of aqueous and organic-based nanodispersions, is proposed as a technological solution to enhance the productivity of heavy crudes and mitigate the aforementioned challenges. This study introduces an experimental methodology for assessing nanofluids, which includes tests for colloidal stability, basic formation fluid characterization, fluid-fluid evaluation, and fluid-rock assessment. During the implementation phase, nanofluids are injected near the wellbore using the matrix stimulation technique, allowing them to be adsorbed onto the rock. This process influences relative permeability curves, modifies wettability, increases the oil recovery factor, and optimizes oil production while simultaneously reducing water production. Finally, the study presents production results following the implementation of nanofluids in a heavy crude well operated by Ecopetrol. The outcomes reveal a significant increase in production, with rates rising from 10 BOPD to 467 BOPD, accompanied by a 37% reduction in %BS&W (based on preliminary post-stimulation tests). The stimulation process included an initial acid stimulation phase, followed by the flowback of the acid returns and subsequent injection of nanofluids.