A contribution to the study of continuous circulation system from economic and environmental point of view

Abstract

Modern drilling in narrow pressure windows faces serious risks from conventional "stop-start" hydraulics, which cause wellbore instability, fluid losses, and high Non-Productive Time (NPT). This dissertation presents a technical, economic, and environmental evaluation of continuous circulation technology, focusing on the Eni Circulating Device (E-CD) in the TAGI and Siegenian formations of the Berkine Basin, Algeria. By comparing field data from a conventional well (HBNEP-6) and a continuous circulation well (LEWN-1), this study analyzes the impact of steady-state hydraulics. Results show that maintaining a continuous flow of 1,800 to 2,200 L/min stabilizes the Equivalent Circulating Density (ECD), preventing connection gases and cuttings settling. Mechanically, the E-CD system eliminated pressure-related stuck pipe incidents, which previously caused 180 hours of lost time on the baseline well. Economically, the technology achieved a Net Economic Saving of $1,072,100 by minimizing downhole trouble time. Environmentally, it eliminated subsurface mud losses and reduced atmospheric emissions by 361.8 tons of CO2 by shortening active rig operations by 7.5 days. This research confirms that continuous circulation optimizes drilling safety, financial performance, and environmental care in high-risk exploration.