Evaluation of Alcohol-Based Treatments for Condensate Banking Removal

Abstract The use of stimulation treatments based on alcohol to remove liquid blockage or condensate banking in the near well zone date from sixties. Among the proposed mechanisms to explain the enhancement in gas effective permeability and also the higher degree of cleaning and liquid removal obtained in laboratory and field studies, are interfacial tension reduction and the miscibility characteristics reached between the treatment fluids and the formation fluids. This paper presents the results for compatibility and displacement tests carried out among reservoir fluids, alcohol and inhibited diesel based treatments and formation cores from main Cupiagua field. These tests are focused about the behavior of these treatments when they are applied in core flooding tests to reduce liquid saturation and also to increase the gas effective saturation in a porous media. The offered results can be interpreted as a preliminary sight about the use of these treatments on lab scale before applying them as stimulation fluids on a field project. The study consists in assess the alcohol-based and inhibited diesel treatments' efficiency through the gas effective permeability before and after of the treatment injection into a core. The objective was focused to study the use of alcohol and inhibited diesel to remove formation damage by liquid blockage and their application in condensate gas reservoirs. The alcohol-based treatments show consistent results about their effectiveness both on core tests carried on Mirador formation, Cupiagua Main Field – Colombia, and Berea sandstone. In general, the results show up an increase on the gas effective permeability, the lower the core permeability the higher the gas effective permeability enhancement reached after the treatment. The alcohol labeled 21-NE-06 and inhibited diesel treatments increase the gas effective permeability both in Berea and Mirador cores. Both Alcohol 21-NE-06 and inhibited diesel based treatments are effective for removing liquid phases that cause a liquid blockage to gas flow. The stimulation degree is higher in Mirador than in Berea cores. Some treatments did not show any stimulation degree, instead, they generate additional gas effective permeability impairment.