National Oilwell Norway As

Jon G Gjedebo

An arrangement for transferring loads by means of one or more hydraulic cylinder-like actuators ( ) in order to establish and maintain tension in a riser ( ) of the type typically used in offshore petroleum production, where the riser ( ) constitutes a connection between the sea bed ( ) and an installation ( ) on or near the surface of the sea ( ), and where the required pressure difference between the pressure side(s) ( ) and the depressurised side(s) ( ) of the actuator(s) ( ) is constituted by a hydrostatic pressure difference.

Riser tensioning arrangement

A method of drilling sub-sea oil and gas production wells in which a liquid hydrocarbon substance, such as a natural gas liquid, is injected into the drilling mud supplied to the well in order to reduce the mud density. The method of the present invention enables reduction and control of the hydraulic pressure of the drilling mud while drilling production wells in deep water, thereby to require fewer casing runs which eventually yields better oil productivity.

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Stavanger, Norway

Jon G Gjedebo