Production Enhancement of Cased-Hole Wells Using Mesophase Fluids

Abstract

Abstract Formation damage is a by-product of the drilling, completion and production process that can be attributed to many factors. In cased-hole wells, the reservoir pressure and hence hydrocarbon flow may be impeded by various damaging mechanisms caused by the drill-in fluid filtrate, in-situ emulsions, water block, and organic deposition. Mesophase chemistry has been developed to remove near-wellbore skin damage in perforated cased-hole applications. This fluid chemistry can be utilized as a perforating fluid and/or be applied during remediation operations to remove the formation damage around the perforation tunnels and/or fracture channels. The physical properties of this mesophase fluid include high oil solubilization, high rates of diffusion through porous media, and the reduction of interfacial tension to near zero between organic and aqueous phases, making them excellent fluids for removing formation damage. This paper presents the development and case histories from numerous field applications that demonstrate the efficiency of mesophase chemistry to reduce skin damage and improve well productivity. Introduction The productivity and ultimate recovery of a hydrocarbon bearing reservoir can be influenced by a number of formation damage mechanisms including changes in wettability, formation of in-situ emulsions, phase trapping, and water block.1–3 Any reduction in the near-wellbore permeability of the formation will have the most significant impact in the productivity of a hydrocarbon producing well, especially wells completed open-hole or in depleted reservoirs that may lack the formation pressure for an effective hydraulic clean-up. Developing drilling, completion, and production strategies to address and minimize the pressure drop associated with a reduction in formation permeability is essential in maximizing hydrocarbon recovery and return on investment. The industry uses various remedial treatments for removing near-wellbore damage, including acids and solvents such as xylene, oils, or alcohols, in combination with surfactants.4–5 These treatments may initially re-establish some lost permeability of the pourous media, however many times they are not completely effective because they do not restore the wettability properties of the rock. Consequently, the production of oil and gas from the reservoir will not be at expected or potential production levels due to the pressure loss induced by formation damage in the near-wellbore.