The Prirazlomnaya Rig Details – Part 2

The Prirazlomnaya platform was designed for operation in the most hostile climate with sub-zero temperatures and a solid ice cover that remains for nearly six months in the production area, where up to 22 storms take place every year. An average storm may last for 9.5 days with an average wave height of 3.9 meters and the maximum wave height reaching 13+ meters. It is designed to resists ice pressure, sea waves and earthquake magnitudes from 5 to 6 on the Richter scale.

Built by Sevmash Production Association, the Prirazlomnaya offshore ice-resistant oil-producing platform (OIRFP) is a key development facility. The platform will ensure well drilling, oil production, storage and offloading. The main features are its resistance to strong ice loads, long self-sustainability and year-round operability. The Prirazlomnaya platform is designed to receive oil from other fields as well. A single platform will enable to involve adjacent fields into efficient development and to reduce infrastructure-associated costs.

The topsides was based on the former UK North Sea Hutton tension leg platform, bought by Rosneft in 2002 and upgraded for its new work at the FSUE Sevmash military shipyard in Severodvinsk. The new platform, Prirazlomnaya, has a field life of 50 years. Platform construction costs were approximately $800 million.

The topsides of the Prirazlomnaya Rig weighs 39,000t. It has a single derrick and 40 well slots. There are two oil-offloading systems with capacities of up to 10,000m³/hr. The topsides sit on a 126m², 97,000t caisson. It includes 14 oil storage tanks with a capacity of 113,000m³, as well as two water storage tanks with a total capacity of 28,000m³. The facility has an oil production capacity of 22,000t/d, a gas production capacity of one million m³/d and will inject water at 32,000m³/d. The superblocks were welded and installed in 2004 followed by the towing and installation the topsides and the concreting.

Control and Safety Technologies

Process operations at the Prirazlomnaya platform are managed with the automated control and safety system. Specific precautionary and emergency measures were introduced in order to eliminate damages caused by oil spills: versatile icebreaker ships are constantly on duty near the platform; the ships have all the equipment onboard needed to localize oil spills at sea. To prevent air pollution, associated petroleum gas is used for process needs – heat and power generation as well as oil treatment.

Gazprom maintains that the Prirazlomnaya platform was designed to exclude the possibility of discharging oil, formation fluid, contaminated industrial and storm waters as well as other harmful substances into the sea. Obviously, how robust and safe the rig really is, only time will tell. Drilling and production waste is either delivered onshore or, like subsurface and oil containing waters, pre-treated before injection into the seabed. Drilling waste may only be injected into the isolated deep beds after being treated; the relevant geological reasoning as well as permits by regional geological departments and sanctions by state sanitary inspectorates must also be given. However all the controls and oversight are Russian and there is no independent auditing of the rigs safety standards, although this may eventually change due to pressure from western governments and environmental institutions. Gazprom is known to have contracted specialists from Schlumberger and Halliburton to attest to the rigs operational safety.