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Artificial islands

Location:
Caspian Sea

The Kashagan oilfield in the North Caspian Sea is the biggest oil field discovered in the past 30 years and under exploitation by a consortium of Kazakh and western companies.

The exploitation is planned in phases to maximize opportunities for exploitation of the oilfield’s full potential. The first phase, the so-called Experimental Programme (EP), comprises experimental drillings and partial development of the oilfield. Phase II, the Full Field Development (FFD), is aimed at full exploitation of the oil reserves.

First islands

Since 1997 Witteveen+Bos Kazakhstan has been delivering consultancy services to the Kashagan-project. In 2001 the design-activities started for the first four artificial islands serving the EP Phase. Satisfactory design results lead to a succeeding design contract for another three artificial islands for the EP Phase in 2005.

Design

Main determinants to the islands’ designs are formed by location-specific conditions such as the water depth, varying from 4 to 6 meters, the extreme climate with temperatures ranging from -35 to +35 degrees throughout the year, and ice loads in winter times.

The island designs consist of a landfill by rock material enclosed by sheet pile walls. Each island has a berthing basin for emergency escape vessels and accommodation vessels for future personnel. The main quay areas and berthing basins are sheltered from floating ice floes and wave attack by rock barriers offshore the islands. Configuration of the islands and the barriers has been determined while utilizing wave modeling programs to ensure safe vessel manoeuvering and mooring operations. The islands are equipped with a subsoil drainage system and prefabricated concrete topside elements such as pavement slabs, well cellars, cable trenches etc.

Design works for the EP Phase are expected to finish in 2010. In parallel, Witteveen+Bos Kazakhstan started design works for artificial islands to Phase II, the FFD.