Designing the First Carbon Capture and Storage Offshore Well in Southeast Sumatra, Indonesia

Abstract The well engineering design of the first Carbon Capture and Storage (CCS) offshore well in Southeast Sumatra, Indonesia, represents a groundbreaking advancement in the nation's efforts to mitigate carbon emissions. This project is a key component of Indonesia's climate strategy, focusing on capturing and safely storing carbon dioxide (CO₂) emissions in subsurface geological formations. The offshore well is located in Southeast Sumatra, targeting the Asri Basin, which introduces unique challenges, particularly in well design, drilling operations, and environmental impact management. In designing a Carbon Capture and Storage (CCS) well, it is essential to ensure the long-term mechanical integrity of the wellbore and to implement effective barriers that prevent the upward migration of injected CO₂, thereby safeguarding overlying formations and groundwater resources (Duguid et al., 2018). This paper discusses the comprehensive process of designing the first appraisal CCS well in the area, including geological and geophysical assessments to identify suitable storage reservoirs, as well as the appraisal well design aimed at confirming the injection rate. Special attention is given to the drilling aspects, which are critical to ensuring the integrity of the well under offshore conditions and in a subsurface carbon-rich environment. Key factors such as wellbore stability, casing design, cement slurry design, the selection of drilling fluids tailored for CO₂ injection, and operational challenges during prolonged injection and completion are explored. The basis of the appraisal well design is to drill the well safely, identifying potential hazards based on studies and the history of offset wells. This paper also presents a feasibility study for the upcoming execution of the project in 2027. The results of the appraisal well will serve as a valuable reference for the future development of CO₂ injector wells.