Managing a HTHP Pipeline: Detailed Integrity Assessment of Deepwater Oil Line Displacement Near Continental Shelf

Abstract

A routine underwater ROV inspection discovered an oil pipeline had moved away up to 3 m distance from its free span rectification supports. This location is at rocky continental shelf irregular seabed, the pipeline had displaced arriving with span exceeding allowable span length. Rectification was undertaken to correct the free span and stop the lateral movement. Since this location was only 20 km away from the hot end, it was noted that pressure and thermal expansion may also significantly contributed to the movement. A later underwater ROV inspection executed when the pipeline was in shutdown condition, some movement in vertical plane and a few support damages was observed. This galvanized the needs to further investigate how the pipeline had responded to pressure and thermal expansion. Subsequent assessment of the survey data and lateral buckling screening identified 12 numbers of uncontrolled buckle formation. Detailed FEA analysis confirmed that the pipeline still comply with the relevant international standard.