Enhancing Deepwater Well Integrity: Design Practices in Riserless and Production Cement Jobs Using Foam Cement – Cases Histories (Mexico, Brazil and Australia)

Abstract Cementing is a critical operation and plays a pivotal role in ensuring well integrity in deepwater environments, where challenges are magnified by extreme depths, narrow pressure windows, complex geological conditions, and significant temperature variations. Under these conditions, the selection and design of cement systems are even more crucial. Achieving effective zonal isolation while managing narrow pressure margins often requires the use of low-density systems. Conventional cement solutions, such as water extended slurries or blends formulated with lightweight additives, often fall short in these settings because they fail to ensure the optimal balance among low density, placement reliability, and mechanical integrity required for effective performance. Foam cement has emerged as a promising alternative, exhibiting several properties that make it suitable for addressing these deepwater challenges: reduced density, enhanced displacement efficiency, pronounced elastic response, and suitable compressive strength. Despite its advantage, foam cement has historically seen limited deployment across global oil and gas operations due to concerns regarding short- and long-term integrity and the additional operational complexity associated with foam cement systems. However, with proper risk assessment, laboratory qualification, supported by systematic planning and rigorous execution, foam cement has proven to be a viable and effective cement solution to address deepwater challenges. This paper presents a comprehensive analysis of the design methodologies and operational practices employed in the successful implementation of foam cement systems for riserless and production casing strings in deepwater wells around the world.