Bringing Back the Damaged Wells into Production Using Microemulsion Technology

Abstract

Investing in new wells during a period of volatile oil prices is not the best option for E&P companies. During hard economic environments such companies make plans to produce or enhance hydrocarbon recovery from existing wells for continuous cash flow and to maximize rate of return on investors’ expectations. In several regions, it may take years to produce the hydrocarbons from the drilled well. These wells were drilled and completed successfully, but they were idle, waiting for the production commencement date. This delay depends on various factors including reservoir conditions, market conditions and geopolitical situations. Due to these delays, wells undergo severe formation damage that either minimizes hydrocarbon production or halts hydrocarbon flow completely. A solution was identified to increase production from a damaged well or bring a non-producing well back into production. This solution is based on microemulsion chemistry. Microemulsions consist of mixtures of oil and water, along with surfactants and other components. These fluids are optically transparent, thermodynamically stable, possess extremely low interfacial tension, and require minimum or zero energy to form. Microemulsions are transparent because of an extremely small droplet size. These are naturally occurring and have less risk involved in deploying and executing the job when compared to conventional solvent treatments. Cleaning efficiency and reaction time of microemulsions depend on many parameters including reservoir conditions, salinity, temperature and type of hydrocarbon used during the drilling or completion phase. These microemulsion fluids were pumped using an inflatable straddle packer (ISP) designed to isolate and divert into the required small area of exposure. The system consists of two inflatable packers with variable spaceout possibilities, enabling adequate positioning over the selective formation area. This tool was deployed using coiled tubing and real-time depth correlation to estimate the correct treatment zones. A customized fluid was designed using specialized surfactants, brine and an acid. These individual components were mixed on the surface and pumped down hole. This blend works by solubilizing oil and emulsifiers from the oil-based filter cake and forming a microemulsion. This paper discusses an openhole completion well that was drilled and then completed with ICD screens. Oil-based mud was left in the hole, causing severe damage that prevented bringing the well back to production. The designed surfactant package was pumped through an ISP tool that was suitable for the reservoir conditions. The ISP tool elastomers were designed after performing detailed lab tests that included the filter-cake destruction test, a wettability test and elastomer compatibility tests. Surfactant was pumped into the reservoir with an engineering approach, and successful results were achieved with good production results.