Abstract: A method for monitoring fluid flow in a conduit comprises: acoustically coupling an optical fiber to the conduit adjacent one or more flow restrictions (R1-R4) in the conduit; inducing a Distributed Acoustic Sensing (DAS) assembly to measure an acoustic noise signature (SNR1-4) generated in the fiber by the fluid flowing through each flow restriction (R1-R4); deriving the fluid flow rate of the fluid (QI, QI+II) flowing through each flow restriction (R1-R4) from the measured acoustic noise signature (SNR1-4); and displaying the derived fluid flow rate (QI, QI+II) at a fluid flow rate monitoring display.

Abstract: A distributed fiber optic acoustic sensing system includes a cable having a cable length. The cable has an elongated body having an outer surface, and at least one straight optical fiber extending parallel to a longitudinal axis of the cable along the cable length; and one or more non-straight optical fibers, such as two orthogonal sinusoidal optical fibers extending along the cable length, or a helically wrapped optical fiber extending along the cable length. The sensing system further has light transmitting and receiving means optically connected to the optical fibers.

Abstract: A distributed fiber optic acoustic sensing system comprises an elongate body having an outer surface, an optical fiber disposed on the outer surface at a first predetermined wrap angle, and light transmitting and receiving means optically connected to the fiber for. The elongate body may include at least one substantially flat face, and/or a layer of swellable elastomer surrounding the body, and/or an outer elastomeric tube surrounding the elastomer layer. There may be at least one sensor pad disposed in the outer layer, the sensor pad comprising a stiffener and at least one longitudinal fiber affixed thereto or embedded therein. There may be a body of protective material surrounding the tube, which may have an outer surface that includes at least one substantially flat face and at least one sensor pad disposed in the body.

Abstract: A method of distributed acoustic sensing includes providing a fiber optic distributed acoustic sensing system having a cable. A straight optical fiber extends parallel to a longitudinal axis of the cable along the cable length. A helically wrapped optical fiber extends along the cable length. The method includes transmitting optical signals into and receiving backscattered signals out of the optical fibers consisting of a component of said optical signals which component has been backscattered from impurities or inhomogeneities in the optical fibers, observing changes in the backscattered signals caused by axial stretching and compressing of the optical fibers caused by an incident wave, comparing the backscattered signals of the straight optical fiber and the helically wrapped fiber, and determining, based on the comparing of the backscattered signals, a direction of wave propagation of the incident wave with respect to the fiber axis for detecting broadside waves and axial waves distinguishably.

Abstract: A distributed fiber optic acoustic sensing system comprises an elongate body having an outer surface, an optical fiber disposed on the outer surface at a first predetermined wrap angle, and light transmitting and receiving means optically connected to the fiber for. The elongate body may include at least one substantially flat face, and/or a layer of swellable elastomer surrounding the body, and/or an outer elastomeric tube surrounding the elastomer layer. There may be at least one sensor pad disposed in the outer layer, the sensor pad comprising a stiffener and at least one longitudinal fiber affixed thereto or embedded therein. There may be a body of protective material surrounding the tube, which may have an outer surface that includes at least one substantially flat face and at least one sensor pad disposed in the body.

Abstract: A distributed fiber optic acoustic sensing system comprises an elongate body having an outer surface, an optical fiber disposed on the outer surface at a first predetermined wrap angle, and light transmitting and receiving means optically connected to the fiber for. The elongate body may include at least one substantially flat face, and/or a layer of swellable elastomer surrounding the body, and/or an outer elastomeric tube surrounding the elastomer layer. There may be at least one sensor pad disposed in the outer layer, the sensor pad comprising a stiffener and at least one longitudinal fiber affixed thereto or embedded therein. There may be a body of protective material surrounding the tube, which may have an outer surface that includes at least one substantially flat face and at least one sensor pad disposed in the body.

Abstract: A method for monitoring fluid flow in a conduit comprises: acoustically coupling an optical fiber to the conduit adjacent one or more flow restrictions (R1-R4) in the conduit; inducing a Distributed Acoustic Sensing (DAS) assembly to measure an acoustic noise signature (SNR1-4) generated in the fiber by the fluid flowing through each flow restriction (R1-R4); deriving the fluid flow rate of the fluid (QI, QI+II) flowing through each flow restriction (R1-R4) from the measured acoustic noise signature (SNR1-4); and displaying the derived fluid flow rate (QI, QI+II) at a fluid flow rate monitoring display.

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: A distributed fiber optic acoustic sensing system comprises an elongate body having an outer surface, an optical fiber disposed on the outer surface at a first predetermined wrap angle, and light transmitting and receiving means optically connected to the fiber for. The elongate body may include at least one substantially flat face, and/or a layer of swellable elastomer surrounding the body, and/or an outer elastomeric tube surrounding the elastomer layer. There may be at least one sensor pad disposed in the outer layer, the sensor pad comprising a stiffener and at least one longitudinal fiber affixed thereto or embedded therein. There may be a body of protective material surrounding the tube, which may have an outer surface that includes at least one substantially flat face and at least one sensor pad disposed in the body.

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: 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 pressure sensor assembly comprises a sensor housing having a flexible wall that is configured to deform in response to a pressure difference between the interior and exterior of the sensor housing; -a first fiber optical cable section that is bonded to the flexible wall of the sensor housing such that the length of the first fiber optical cable section changes in response to deformation of the wall in response to the said pressure difference; a second fiber optical cable section which is bonded to a thermal reference body, which body is connected to the sensor housing by a strain decoupled connection mechanism, such as a tack weld or flexible glue, and is configured to deform substantially solely in response to thermal deformation, such that the length of the second fiber optical cable section solely changes in response to thermal deformation of the thermal reference body.

Abstract: A method is disclosed for producing hydrocarbon fluids through a well having a well casing string with a casing section which is surrounded by an annular space which comprises a sensor assembly for measuring electromagnetic and/or other physical properties of solid and fluid materials within the annular space, in an underground formation surrounding the annular space and/or within the interior of the section of the casing string, wherein the sensor assembly is mounted on a body of swellable material, such as a swellable rubber or other elastomeric material, which is secured to the outer surface of said casing section and presses the sensor assembly against the inner surface of the surrounding underground formation after the casing string has been lowered into the wellbore.

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 pressure sensor assembly comprises a sensor housing having a flexible wall that is configured to deform in response to a pressure difference between the interior and exterior of the sensor housing; —a first fiber optical cable section that is bonded to the flexible wall of the sensor housing such that the length of the first fiber optical cable section changes in response to deformation of the wall in response to the said pressure difference; a second fiber optical cable section which is bonded to a thermal reference body, which body is connected to the sensor housing by a strain decoupled connection mechanism, such as a tack weld or flexible glue, and is configured to deform substantially solely in response to thermal deformation, such that the length of the second fiber optical cable section solely changes in response to thermal deformation of the thermal reference body.

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: Tubular ends are heated to a predetermined temperature above 1200 degrees Celsius and surrounded by a shield gas when the tubular ends are pressed together to form forge welded tubular ends. The forge welded tubular ends are then cooled down rapidly from said temperature above 1200 to at most 600 degrees Celsius within 3 minutes after the forge welding operation.

Abstract: A fiber optical sensing cable is inserted into an underwater well by: connecting a housing (12A) comprising a coiled or spooled U-shaped fiber optical sensing cable (21) to the wellhead (2) of the well (1) such that an opening (14) in the wall of the housing (12A) is connected to a guide tube (15) extending into the underwater well (1); —inserting the U-shaped nose section (21A) of the fiber optical sensing cable (21) via the opening (14) into the guide tube (15), thereby uncoiling at least part of a pair of substantially parallel sections of the fiber optical sensing cable of which the lower ends are interconnected by the U-shaped nose section; and connecting the upper ends (21B) of the substantially parallel sections of the fiber optical sensing cable to an optical signal transmission and/or receiving unit via e.g. a pair of wet mateable connectors that are connected to a pair of underwater fiber optical transmission cables (14).