Abb Offshore Systems Limited

Viper Innovations Limited

Neil Irwin Douglas

Paul Robert Overton

Alistair John Wright

Hugh R Clayton

Described is a cable rejuvenation apparatus for a cable used in a subsea environment. The apparatus applies a bias signal to a conducting element of the cable, the bias signal being selected to improve the insulation properties of the cable. The bias signal is generated by a bias signal generator that includes a voltage source that generates a bias voltage having a time varying component. The bias voltage promotes an electrochemical reaction between the conducting element and the salt containing liquid of the subsea environment resulting in the formation of a barrier material at the fault location restricting further leakage current flow and enhancing the insulation resistance of the cable. The bias signal is a voltage selected such that the electrochemical reaction promoted by the bias voltage maintains the presence of the barrier material at the fault location.

Rejuvenation of subsea electrical cable insulation

Described is a rejuvenation method for a cable used in a subsea environment. The method includes applying a bias signal to a conducting element of the cable, the bias signal being selected to improve the insulation properties of the cable. The bias signal is selected such that, in the event of an electrical leakage current of predetermined magnitude flowing between the conducting element and a salt containing liquid of the subsea environment at a fault location. The bias signal can be a voltage which promotes an electrochemical reaction between the conducting element and the liquid resulting in the formation of a barrier material at the fault location restricting further leakage current flow and enhancing the insulation resistance of the cable. The bias signal is selected such that the electrochemical reaction promoted by the bias signal maintains the presence of the barrier material at the fault location.

An apparatus for sensing strain applied to a region of a hydrocarbon well comprises an optical fiber in communication with the region. The optical fiber is responsive to strain applied to the region and to a light signal transmitted through it, in order to produce a sensing light signal incorporating scattered light. A characteristic of the scattered light is indicative of the strain being applied to the region.

Sensing strain in hydrocarbon wells

It is desirable to be able to monitor the condition of a filter in a fluid flow system, for example a sandscreen in a fluid well. The invention provides monitoring apparatus including an optical fibre having a pressure sensor . Pressure is exerted on the sensor, by fluid flowing through the sandscreen, via ports and . The pressure sensor is responsive to a light signal, and to the exerted pressure, to produce a sensing light signal indicative of a characteristic of the fluid flow, such as pressure differential or fluid velocity. This, in turn, is indicative of the condition of the sandscreen or filter.

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Clevedon, United Kingdom

Neil Irwin Douglas