Caisson Investigation Study/Repairs

Samphire Subsea Case Study

A central North Sea platform caisson sheared at the caisson guide during a winter storm and fell to the seabed. A large section was embedded in the seabed with the other end resting against jacket members.

Samphire was engaged at short notice in support of the immediate ‘make safe’ response and requested to complete an engineering study to provide guidance on the options for debris removal associated with the failure.

Caisson Investigation

The main platform export line is located almost directly below the failed caisson which carried considerable risk in any solution development. At short notice Samphire pulled an experienced multi-discipline team together to frame the options which were further developed and evaluated.

A phased solution was eventually recommended, where the most critical activities (removing / repositioning of pump string, protective grout bags) were performed first, followed by development of restraint solutions related to long-term stability. It was assessed that recovery of the caisson presented greater risks than leaving it in situ and providing appropriate stabilisation. As a result of this work the operator was able to make safe the current situation and re-establish production from the asset in a relatively quick timeframe.

Work Screening / Evaluation Equipment Criticality Review Risk Management Caisson Investigation Study/Repairs Subsea IRM - General Subsea Support Brownfield Project Execution Work Execution Pigging Campaign Management Subsea Engineering - Single Vessel Solution Subsea Controls Obsolescence Package Management Subsea Facilities Life Extension Subsea Decommissioning Services