Review of gas migration and wellbore leakage in liner hanger dual barrier system: Challenges and implications for industry

Robust dual barrier systems are crucial for well integrity. Regulators and industry have consistently raised the concerns in such systems regarding the leak pathways and its failure modes prediction, testing, and qualification. Liner hanger is an example of dual barrier system in which seal assembly and cement sheath act as two barrier elements. The liner hanger system is usually employed in complex operating environments such as high-pressure and high-temperature (HPHT), deep-water, and ultra-deep-water. In these harsh environments, the gas migration through such system has been attributed to several well control incidents. To investigate this problem, a thorough review of underlying complexities, leakage mechanisms, liner hanger seal assembly materials, dominant failure mechanisms in seal and cement, and the gap in current standards and regulations is conducted. Overall, the objective of this paper is to understand the nuances of the liner hanger dual barrier system and to identify the risks of failures that could compromise the wellbore integrity.