Innovative Fluid Technology Enhanced Wellbore Integrity, Optimizing Casing Sections in the Bandurria Sur Field in Argentina

Abstract

Abstract In the Neuquen Basin in Argentina, the Bandurria Field is notorious for its narrow operational window, which is caused by the difference in pressure gradients between formations. This environment often demands the use of managed pressure drilling (MPD) technology in addition to a robust well design, with several planned sections, and can substantially increase the cost of well construction. To extend the pressure-gradient operative window, the operator opted for a new drilling fluids-focused technology and operational strategy which reduced the number of casing sections. The ultimate objective of the operator was to construct a productive and cost-effective well, while maintaining wellbore stability between challenging formations. Using a break-even price objective of just over 40 USD/bbl, a strategy the operator adopted was the use of an ultra-resistant and flexible fluid technology in the open hole section, using a technology engineered within the drilling fluid system to ensure that newly drilled rock was rapidly sealed and protected enabling to work with the same drilling fluid density two different formation pressures. Using this technique, the operator executed a successful operation, expanding the operating window and limiting wellbore instability while drilling into the two problematic formations. With the use of MPD, offset wells on the same pad presented significant operational challenges, including wellbore instability from stuck pipe, sidetracks, and lost circulation of the drilling fluid. The implemented technology and technique, referred to as a Fluid Stabilization Additive (FSA), allowed the operator to perform a dynamic formation integrity test (DFIT) while drilling through the transition zone to evaluate the magnitude of the operative window increase and compare the results to offset wells on the same pad. The Fluid Stabilization Additive enabled a 1-2 lb/gal increase beyond the fracture gradient window, which was observed in the field. The FSA was used in additional wells drilled in the same formation, which resulted in a considerable improvement in the drilling efficiency when compared to offset wells. Another economic advantage for the operator was the savings of oil-based drilling fluid (OBM) that was utilized for each well. Drilling fluid savings, and the prevention of lost mud to the formation minimized the total cost of the drilling fluid and helped to maximize the efficiency of the drilling operations. Finally, a comprehensive laboratory evaluation was conducted to compare the efficacy of this unique approach. The Bandurria Sur Field was drilled at a much lower cost as a result of the FSA and modification to the drilling fluid formulation.