One of the most common challenges faced by well operators worldwide is extending the lifetime of their aging platform wells. The initial well construction, operational loading and time-dependent deterioration of a well through field life are all key factors that need to be understood to establish the remaining capacity of a well. However, often these factors are not fully understood and consequently costly decisions to repair or abandon wells can be made unnecessarily, or in some cases critical wells or operations on wells are not identified, risking structural collapse of a well. To address these issues, this paper describes the factors that influence the integrity of the well, and presents advances in the approaches to understand and evaluate the condition of a well and hence better evaluate remaining capacity. Methods, Procedures, Process: Typically, corrosion of the casings is taken as the key parameter to establish a well’s remaining capacity. However, as demonstrated in this paper through an analytical evaluation, the axial loading in the well is another key parameter that needs to be understood. A range of factors affect the well axial loads based on well construction and deterioration is considered, including:

• Weight of casing hung off wellhead during installation
• Level of axial support provided by casing shoe
• Cement levels
• Changes to well configuration
• Changes to well service (Producer to Injector)
• Changes to operating temperatures and pressures through field lifeLevel of axial support provided by casing shoe