Abstract: A method for determining the physical location of a fiber optic channel in a fiber optic cable comprises the steps of a) providing at least one location key having a known physical location, b) establishing the location of the location key with respect to the fiber optic channel, and c) using the location information established in step b) to determine the physical location of the channel. The location key may comprises an acoustic source, a section of fiber optic cable that is acoustically masked, or at least one magnetic field source and step b) comprises using a Lorentz force to establish the location of the magnetic field source with respect to the fiber optic channel.

Abstract: The spatial resolution of a fiber optical Distributed Acoustic Sensing (DAS) assembly is enhanced by: arranging an optical DAS fiber with a series of contiguous channels that are sensitive to vibration in a U-shaped loop such that substantially parallel fiber sections include pairs of channels that are arranged at least partially side by side; transmitting a series of light pulses through the optical fiber and receiving back reflections of said light pulses by a light transmission and receiving assembly; and processing the received back reflections such that back reflections stemming from at least one pair of channels that are arranged at least partially side by side are correlated to each other.

Abstract: A distributed acoustic sensor, comprises a housing having a longitudinal bore therethrough, an optical fiber supported in the bore; and an inertial member supported within the bore, wherein the fiber is mechanically coupled to the inertial member. The inertial member may include a weight and may provides isotropic stiffness such that it deforms more readily in a first direction normal to the bore than it does in a second direction that is normal to both the bore and the first direction. The sensor may include a plurality of axially-spaced centralizers in the bore, and at least one of the inertial member and the centralizers may comprise swellable material.

Abstract: The location of one or more fiber optic channels (16) along the length of a fiber optic cable (12) is determined by: a) arranging an electrical conductor and a magnetic source at a known location adjacent to at least one of the channels (16); b) transmitting an electrical current through the electrical conductor, thereby deforming the electrical conductor by Lorenz forces in the vicinity of the magnetic source; c) conveying the deformation of the electrical conductor to deform an adjacent channel (16); d) transmitting light pulses through the fiber optic cable (12) and using variations in the light pulses back reflected by the deformed channel (16) and the known location of the magnetic source to determine the location of the deformed channel (16).

Abstract: A distributed acoustic sensor, comprises a housing having a longitudinal bore therethrough, an optical fiber supported in the bore; and an inertial member supported within the bore, wherein the fiber is mechanically coupled to the inertial member. The inertial member may include a weight and may provides isotropic stiffness such that it deforms more readily in a first direction normal to the bore than it does in a second direction that is normal to both the bore and the first direction. The sensor may include a plurality of axially-spaced centralizers in the bore, and at least one of the inertial member and the centralizers may comprise swellable material.

Abstract: A system for monitoring subsidence and/or rising of a waterbottom has string of pressure sensors along the interior of a sealed -protective tube(q?) that rests on the waterbottom and is filled with a low pressure liquid, so that any subsidence and/or rising of the can be deduced from subsidence and/or rising of a section of the tube and associated pressure variations measured by the sensors due to variation of the hydrostatic fluid pressure of the liquid in the of the tube. The tube interior is divided into segments by valves during descent to protect the sensors against hydrostatic pressure of the liquid within the tube during installation. The use of a low pressure liquid in the tube allows the use of sensitive pressure sensors which are able to monitor pressure variations of ?0.001 Bar associated with a waterbottom subsidence of ?1 cm, at a water depth of >km where the ambient water pressure may be >100 Bar.

Abstract: A method for determining the physical location of a fiber optic channel in a fiber optic cable comprises the steps of a) providing at least one location key having a known physical location, b) establishing the location of the location key with respect to the fiber optic channel, and c) using the location information established in step b) to determine the physical location of the channel. The location key may comprises an acoustic source, a section of fiber optic cable that is acoustically masked, or at least one magnetic field source and step b) comprises using a Lorentz force to establish the location of the magnetic field source with respect to the fiber optic channel.

Abstract: The location of one or more fiber optic channels (16) along the length of a fiber optic cable (12) is determined by: a) arranging an electrical conductor and a magnetic source at a known location adjacent to at least one of the channels (16); b) transmitting an electrical current through the electrical conductor, thereby deforming the electrical conductor by Lorenz forces in the vicinity of the magnetic source; c) conveying the deformation of the electrical conductor to deform an adjacent channel (16); d) transmitting light pulses through the fiber optic cable (12) and using variations in the light pulses back reflected by the deformed channel (16) and the known location of the magnetic source to determine the location of the deformed channel (16).

Abstract: Voids (14) in a underground wellbore (1) are sealed by:—inserting a corrosion prone object (10A-C, 12) in the void injecting an oxidizing agent into the void (14); and—allowing the oxidizing agent to induce corrosion of the corrosion prone object and to thereby generate corrosion products (13A-E) that are physically larger than the corrosion prone object (10A-C, 12) and that seal the void (14).

Abstract: The spatial resolution of a fiber optical Distributed Acoustic Sensing (DAS) assembly is enhanced by: arranging an optical DAS fiber (1) with a series of contiguous channels (C1-C14) that are sensitive to vibration in a U-shaped loop (U1) such that substantially parallel fiber sections (IA, IB) comprise pairs of channels (C1&C14, C2&C13,C3&C12 . . . etc) that are arranged at least partially side by side; transmitting a series of light pulses (5A, 5B) through the optical fiber (1) and receiving back reflections (6A, 6B) of said light pulses (5A, 5B) by a light transmission and receiving assembly (7); and processing the received back reflections (6A, 6B) such that back reflections stemming from at least one pair of channels (C1, C14; C2,C13) that are arranged at least partially side by side are correlated to each other.

Abstract: A system for monitoring subsidence and/or rising of a waterbottom has pressure sensors along the interior of a sealed tube that rests on the waterbottom and is filled with a low pressure liquid so that subsidence or rising of the waterbottom can be deduced from subsidence and/or rising of a section of the tube and associated pressure variations measured by the sensors due to variation of the hydrostatic pressure of the liquid in the tube. The tube interior is divided into segments by valves during descent to protect the sensors against hydrostatic pressure of the liquid within the tube during installation. The use of a low pressure liquid in the tube allows the use of sensitive pressure sensors which are able to monitor pressure variations of ˜0.001 Bar associated with a waterbottom subsidence of ˜1 cm, at a waterdepth of >km where the ambient water pressure may be >100 Bar.

Abstract: A method is disclosed for producing hydrocarbons through an instrumented smart well containing a well tubular (6,29-32) and an assembly of power, DTS and/or other sensing and/or signal transmission cables (13,40-44) comprising at least one power and/or signal transmission cable, which is bonded along at least part of its length to an outer surface of the well tubular (6,29-32) by an adhesive, which preferably is reusable and/or has a thermal conductive of at least 3 W/mK or at most 0.2 W/mK.

Abstract: A method of operating a downhole component (for example a battery pack) comprising at least one electrolyte based element. The method comprising the steps of locating the component in a downhole environment and whilst the component is in the downhole environment subjecting the element to a pressure in excess of atmospheric pressure to suppress at least one of boiling and evaporation of electrolyte in the element. The component may then be operated at a temperature in excess of that which would be tolerated by the electrolyte based element if not subjected to a pressure in excess of atmospheric pressure.

Abstract: Method systems and apparatus for signalling within pipelines. The systems methods and apparatus make use of a unit locatable within a tubular piece of metallic structure for the transmission and/or reception of signals. The unit includes a magnetic material core (6) which provides a path for magnetic flux through the unit (4). A coil (81) is wound around a portion of the magnetic material core (6) to allow the detection and/or application of magnetic flux in the magnetic core (6). At each end of the core (6) there is pair of arms (63) which are arranged for location adjacent the inside surface of the tubular structure. In use magnetic signals flowing in the tubular structure pass through the core (6) and can be detected via the coil (81) in receive mode and similarly signals flowing in the coil (81) can cause magnetic flux to flow through the core (6) and into the metallic structure in transmit mode.

Abstract: Data transmission in pipeline systems A first set of apparatus is arranged for transmitting data from a point in a cased section of a well 1, 3 to a remote location. The apparatus may be used as a relay station 6 to increase operational depth. Signals are applied to and received from the string 1 at the relay station 6 and a selected length of the string 1 is provided with insulating spacer means 9 on either side of the relay station to ensure that the string 1 and casing 3 are effectively isolated for a selected minimum distance. This enables potential differences to be both applied to and detected from the string 1, thus allowing data transmission and reception. A second set of apparatus is arranged for transmitting from an internal unit 408 inside a cased section of the well 401, 403 to the immediate surrounding area outside the casing 403. The internal unit 408 injects current into the string 401. A toroid 415 which surrounds the casing 403 is provided to pick up signals.

Abstract: Method systems and apparatus for signalling within pipelines. The systems methods and apparatus make use of a unit locatable within a tubular piece of metallic structure for the transmission and/or reception of signals. The unit includes a magnetic material core (6) which provides a path for magnetic flux through the unit (4). A coil (81) is wound around a portion of the magnetic material core (6) to allow the detection and/or application of magnetic flux in the magnetic core (6). At each end of the core (6) there is pair of arms (63) which are arranged for location adjacent the inside surface of the tubular structure. In use magnetic signals flowing in the tubular structure pass through the core (6) and can be detected via the coil (81) in receive mode and similarly signals flowing in the coil (81) can cause magnetic flux to flow through the core (6) and into the metallic structure in transmit mode.

Abstract: A method of operating a downhole component (for example a battery pack) comprising at least one electrolyte based element. The method comprising the steps of locating the component in a downhole environment and whilst the component is in the downhole environment subjecting the element to a pressure in excess of atmospheric pressure to suppress at least one of boiling and evaporation of electrolyte in the element. The component may then be operated at a temperature in excess of that which would be tolerated by the electrolyte based element if not subjected to a pressure in excess of atmospheric pressure.

Abstract: Data transmission in pipeline systems A first set of apparatus is arranged for transmitting data from a point in a cased section of a well 1, 3 to a remote location. The apparatus may be used as a relay station 6 to increase operational depth. Signals are applied to and received from the string 1 at the relay station 6 and a selected length of the string 1 is provided with insulating spacer means 9 on either side of the relay station to ensure that the string 1 and casing 3 are effectively isolated for a selected minimum distance. This enables potential differences to be both applied to and detected from the string 1, thus allowing data transmission and reception. A second set of apparatus is arranged for transmitting from an internal unit 408 inside a cased section of the well 401, 403 to the immediate surrounding area outside the casing 403. The internal unit 408 injects current into the string 401. A toroid 415 which surrounds the casing 403 is provided to pick up signals.