Overcoming Formation Stability Risks and Optimizing Drilling Time using Continuous Circulation System (CCS) for the First Time in the Colombian Foothills

Abstract

Abstract The largest oil and gas operator in Colombia often faces challenges when drilling in the Llanos Foothills oilfield because of the area's complex geology. Issues typically occur in the Carbonera Coal formation, which is characterized by the presence of fractures with equivalent coal permeabilities and high-pressure fluctuations during conventional drilling operations. These characteristics create operational complications, such as stuck pipe caused by cuttings and difficulty during wellbore cleanout caused by cuttings decantation or caving when circulation stops (Fig. 1). Continuous circulation systems (CCS) help mitigate undesired wellbore geometrical effects and potential packoff during connections, which can save rig time and generate additional benefits, such as cooling of the measurement while drilling (MWD) tools and maintaining bottomhole pressure (BHP) control during drillpipe connection. By using a CCS in the Llano Foothills, the operator reduced the operation by seven days and total capital expenses by 1.05%. Additionally, sidetrack drilling was avoided, which saved time and helped reduce carbon emissions by 204.9 TCO2e with no health, safety, or environmental (HSE) incidents. The first implementation of this CCS in Colombia is discussed and highlights a novel way to plan and execute drilling projects with the geological components of the Llanos Foothills. This technology was successfully used in the C7 and C8 units of the Carbonera Coal formation and could potentially be used in other areas of similar complexity.