20 YEARS DECOMMISSIONING EXPERIENCE - EVOLUTION OF INNOVATIVE SOLUTIONS

Abstract

Decommissioning is an increasing market sector which has been gradually gathering momentum particularly in the North Sea. The forecast expenditure for removing existing platforms increases with time. This comes together with the increasing complexity of the decommissioning operation. Experience and expertise in this field are key for success. Saipem have been contracted to perform a number of ‘removals’ ranging from subsea templates, subsea pipelines, seabed debris clearance, jacket structures and topside modules. This paper provides an account of our experience gained over the last 20 years performing decommissioning activities. The paper presents the evolution of the techniques developed and focuses in particular on the Lift and Tow method developed after 2004 for a number of subsea applications. Problems always materialise post contract award due to inadequate data. The paper gives a detailed description of the Lift and Tow method along with various innovative techniques developed for this method, ranging from lifting operations supported by motion forecasting through to personnel access onto the structures.