Decommissioning Q1 platforms

For the Q1 offshore field, Iv participated in the decommissioning of numerous platforms, including Helm, Hoor, Helder, Horizon, and Halfweg. The work took place in multiple project phases. With regard to Helm, involvement goes back beyond decommissioning; in the 1990s, Iv prepared drawings for the fabrication of the platform.

The projects were part of a single programme in which the platforms were removed and transported step-by-step for onshore decommissioning. Various contractors were commissioned to perform this work, including Heerema Marine Contractors, DEME, and Sagro.

In the early phase, Iv’s scope included, among other things, undertaking feasibility studies and lift analyses. This was followed by engineering for the execution of decommissioning and transport.

For Halfweg, Iv also performed damage analyses following a collision, as well as engineering for the removal of the platform and gravity base structure.

In later phases, Iv carried out offshore inspections and prepared weight reports. In addition, Iv designed grillage, sea fastening, set-down guides, and lifting tools for transport and hoisting operations.

The platforms featured diverse configurations, structural compositions, and a long operational history, as a result of which the information available was not always complete or was ambiguous. Therefore, the weight, centre of gravity, and structural properties of each platform had to be determined based on drawings, inspections, and additional analyses. The data gathered formed the basis for determining loads during transportation, and the design of support structures.

Subsequently, detailed analyses of the interaction between structures and transport frames had to be performed. This led to design challenges, particularly with regard to jacket transportation, whereby stability, force distribution and feasibility had to be closely aligned. Additionally, the scope and duration of the programme placed high demands on quality assurance and the collaboration between the parties involved.

The technical analyses formed the basis for a controlled execution of the activities taking place within the Q1 field. Providing insight into structural behaviour and loads during critical operations for each platform made risks manageable and substantiated execution choices. The execution was supported by Iv in line with relevant regulations and international agreements for the removal of offshore infrastructure, ensuring the availability of the area for future uses, including shipping and fishing.