Thru-Tubing Resin Milling Operation with Coiled Tubing Saves Well During Complex Abandonment in Non-Oil and Gas Reservoir in Brazil

Abstract

Abstract

Abstract Based on the increasingly and more frequent developments in exploration and production of non-oil and gas reservoirs at a global level, key factors have been identified for each stage of well drilling, completion, production, and abandonment. The latter presents some of the most significant challenges with a wide array of opportunities for improvement to address factors inherent in the well's lifecycle, such as high geological dynamics, corrosive environments, completion damage, etc. However, an innovative option arises in the form of drilling interceptor wells (lateral access to the main well) as a mandatory and efficient measure for well abandonment using resin-based cement systems, which offer high performance in terms of mechanical stress management, low solids content, excellent adhesion (400% greater than conventional cements), and high isolation guarantee. This option comes with new challenges as the resin, which provides superior mechanical stress tolerance, exhibits elastic behavior over conventional cement slurries. Consequently, this adds complexity to the milling process and subsequent access to target depths through confined spaces for subsequent plug abandonment. This requires a thorough and precise study of the necessary tools (downhole motor, type of bit/underreamer), coiled-tubing strings, procedures, limitations, and contingencies, to ensure the fulfillment of objectives outlined both technically and economically. A non-oil and gas well plug is discussed that uses resin-base cement (through an interceptor well), a material composed of polymeric base and additives, to provide the mechanical properties necessary to achieve hydraulic isolation. Additionally, this study highlights key operational lessons learned and provides a technical benchmark for future abandonment campaigns involving resin-based cement systems in non-conventional reservoirs. The results demonstrate that proper integration of coiled tubing technology and optimized milling parameters can significantly enhance operational efficiency and ensure well integrity under complex conditions.