Gas migration along wells from reservoir formations to shallow sub-seabed strata was identified to occur at a field, offshore Malaysia. Since 1993 numerous shallow gas kick events had occurred in the vicinity of the platform designated in this paper as Platform DB, at gas charged layers of 60m and 90m below mudline. The occurrence of shallow gas kicks is a concern as it relates to the development of excess pore water pressure in soil which in turn can potentially impose detrimental effect to foundation integrity.
Due to the dynamic nature of shallow gas migration at various depths around the subject platform, the foundation integrity of the platform complexes needs to be monitored to ensure that possible progressive increase in excess pore pressure can be identified and reduced to maintain foundation integrity.
This paper describes the efforts undertaken by Petronas Carigali Sdn Bhd (PCSB) to install the XPP@TM monitoring tool to measure the magnitude of the excess pore pressures. This paper also discusses the studies undertaken to understand the extend of the shallow gas migration and the mitigation plans that are put in place to monitor the foundation integrity at the designated Platform DB. Equipment design and operational procedures are also presented to record the efforts undertaken by PCSB engineers to ensure that XPP@TM Monitoring Tool is robust and fit for purpose.
