Abstract

Huge hydrocarbon resources, expected to be present in the Arctic area, have led the industry to explore the deposits of the Arctic seas, though such exploration is very challenging. Jack-up units are normally applied for drilling in shallow ice-free Arctic waters. Conventional jack-ups can be utilized only during the open water season. The installation of a jack-up can take place after the ice cover has cleared sufficiently for the jack-up to be maneuvered to site. At the end of the drilling season, the jack-up should be moved away before the sea freezes up, as the jack-up could get stuck in the ice cover.

The paper describes a new jack-up drilling rig concept suggested for shallow Arctic waters such that the drilling season can be extended by several weeks as compared with existing jack-up drilling rigs. The suggested concept comprises a ship-shaped hull with icebreaking capabilities and four columnar legs placed on outrigger arms and equipped with protective collars so the jack-up can withstand ice loads in the early ice period. Drilling through one of the jack-up legs is suggested to protect the drill string from possible ice impact at the end of the drilling season. This leg should have a telescopic design so that the derrick could be skidded over it before drilling.

The research comprises a detailed description of the main concept features and the estimation of the possible drilling season extension using the example of the Pechora Sea ice conditions. The study concludes that the considered jack-up can be an effective solution for exploration of shallow Arctic waters. The suggested jack-up design allows the crew to continue drilling operations for at least four to five weeks after the ice has started to form on the drilling site and to leave the location safely without costly icebreakers' assistance. In case a relief well has to be drilled in the area, the drilling season could be further extended with the implementation of heavy ice management.

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