(47bx) Identifying and Quantifying MAJOR Hazard for Platforms Deck Raising Using Synchronous Hydraulic Jacking System

Lima Flow Station is one of gathering manned station of Pertamina Hulu Energy Offshore North West Java (PHEONWJ) which is located in Java Sea, Indonesia. The Lima Flow Station consists of four bridge linked platforms and a bridge linked flare structure. Lima Flow Station  was experienced subsidence for about 3 meters since it was built on 1973 to early 2013. The subsidence caused significant reduction in the platform air gaps (distance between cellar deck bottom of steel and maximum wave height) which cause Lima Flow Station did not reliable for safe operation.

The synchronous hydraulic jacking system was selected to raise the platform to 4 meters elevation and remedy the air gap for safe operation. Three platforms, Flare tripods, and interconnecting bridge was raised while one platform was not raised as it was isolated and utilized as muster point and personnel transfer purpose only. The same technology has been successfully applied in Gulf of Mexico in 2006.

Quantitative Risk Assessment (QRA) study was conducted for the design of synchronous hydraulic jacking system to measure whether the design provide tolerable risk or not and identified mitigation of any un-tolerable risk. The assessment was carried out in two main parts: hazard identification in the form of failure modes, effects and criticality analysis (FMECA) to determine major accident events to be carried forward into the QRA; and determination of the impact of safety risk to personnel and assessment of financial risks in the form of delays to resumption of production.

FMECA was used for qualitative and semi- quantitative analysis of engineering systems. The reviewed system was divided to system, subsystem, and equipment. Failure mode, cause, safeguard and effect/consequence for equipment are identified. High consequence was considered as major accident and is further studied in QRA.

QRA was consist of Fault Tree Analysis (FTA) to estimate the probability of major accident event identified by FMECA, Event Tree Analysis (ETA) to estimate of probability of major accident leading ultimate event, Consequence analysis to estimate impact of the ultimate event, risk estimation by multiplying probability and impact of ultimate event, risk assessment by comparing estimated risk and risk criteria, and identify mitigation for any major accident having un-tolerable risk.

FMECA has identified some major accident events which caused by misalignment and structural failure during deck rising. The results of the QRA determined that the individual risk per annum for the most exposed individual is still within tolerable risk of company’s criteria as the deck raising is conducted during shutdown and minimum manning level. While for financial risk is high for platform damage due to structural failure for lifted platforms as there was not detection method for structural failure and sudden movement in case of structural failure may cause major damage. The financial loss was mostly contributed by production loss. The major contributor for structural failure is welding failure. Recommendation was raised to minimize the risk by providing extra quality check for welding and material of structural parts on fabrication and installation.

By implementing good project and risk management, Lima Flow Station Deck Raising has completed successfully and just start-up in October 2013 without any accident.