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.

An arrangement for transferring loads by means of one or more hydraulic cylinder-like actuators (19, 26, 40) in order to establish and maintain tension in a riser (1) of the type typically used in offshore petroleum production, where the riser (1) constitutes a connection between the sea bed (2) and an installation (4) on or near the surface of the sea (6), and where the required pressure difference between the pressure side(s) (18, 42) and the depressurised side(s) (17, 46) of the actuator(s) (...

A tensioning device (15) for a riser (5) connecting a subsea borehole (7) with a floating installation (1) on the surface of the sea (11), where the tensioning device (15) is provided with telescoping tubes (27, 27') and also several evenly spaced hydraulic cylinders (31, 31') arranged in a peripherally encircling manner and mainly in the longitudinal direction of the riser, and where the tension in the riser is exerted through hydraulic pressure in said cylinder (31, 31'), the tensioning device...

A piston engine in the form of a piston pump or a piston engine (motor) comprises two or more piston cylinders (14b, 14c), preferably positioned with the same angular distances of 180 degrees for two cylinders, 120 degrees for three cylinders etc. with regards to an axis, and each comprising a reciprocating piston with a projecting piston rod (18b, 18c). Via the piston rods (18b, 18c), each piston is given a controlled displacement matched to the controlled, given displacement of another or othe...

In spinner tongs, a so-called spinner (30), incorporated in an iron roughneck and thus serving to rotate a drill pipe during connection thereof to a drill string or during division of the drill string into individual pipes, the aim has been to reduce damage on the threaded connections (the pin-and-box joints) in the screwing/unscrewing operations. This is realised in an operation for the simultaneous centering and rotating of the drill pipe. Four spinner rollers (42) known in themselves, which a...

A method of and device for detecting a leak in reciprocating machinery, comprising at least two pistons, by the volume flow at least out of the reciprocating machinery being monitored and analysed, e.g. by means of Fourier analysis, in order to make it possible to detect a flow component, where the flow component has a frequency that differs from the fundamental frequency of the reciprocating machinery, the fundamental frequency of the reciprocating machinery being constituted by the rotational ...

A device for tensioning and relieving production tubing (49) extending from a subsea hydrocarbon well (107) up through a riser (63) to a floating installation (87), a continuous production tubing extension (85) passing through a telescopic unit (67) in the upper part of the riser (63), preferably extending above a production deck (89) on the floating installation (87), where the production tubing (49) is provided with a tubing tensioner unit (1) below and in the proximity of the lower end of the...

A method and a device for determining if or where a person (10) is located within an area (5), wherein a foot transceiver (8) connected to the person (10) activates one or several identifiable transponders (6) placed in the area (5), after which the activated transponder(s) (6) emit an identifiable signal, preferably via the foot transceiver (8), onto a main receiver/transmitter (14), each of the received signals then being referred to a known position.

A valve arrangement for reciprocating machine, where the arrangement (1) comprises an in-valve (18) and an out-valve (19), each valve (18), (19) being a springloaded one-way valve designed to open for flow when the pressure differential in the direction of flow provides a force that exceeds the spring tension, wherein the valves (18, 19) are mounted in a casing (8) that forms or is connected to the cylinder head of the reciprocating engine (2). The in-valve (18) and the out-valve (19) are mounte...

A device for a single-acting hydraulic cylinder (1) designed to lift or pull a load upon the existence of an oil pressure on the rod-side of a cylinder piston (7), where the cylinder bottom (15) of the hydraulic cylinder (1) is provided with a drainage outlet (27) for leakage fluid, as well as an air inlet (29).