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 system for use in a wellbore, comprises a length of casing, a structure that is configured to deform with deformation of the casing, said structure being affixed to the length of casing at substantially the same radial position along the length of casing, and a sensing device that is configured to measure deformation of the structure, said device comprising a plurality of sensors that are distributed with respect to at least one of the length of said structure and the periphery of said structure.

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 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: Integrated fiber optic monitoring techniques for a wellsite are provided. A fiber optic cable is provided with a tubular housing having a channel and a plurality of slots, a plurality of optical fibers may be floatingly positionable in the channel for measuring at least one first wellsite parameter and a plurality of optical fibers fixedly may be positionable in each of the slots for measuring at least one second wellsite parameter. The tubular housing is positionable into a wellbore adjacent a tubing therein. Pairs of the fixed and floating optical fibers may be spliced together to perform Stimulated Brillouin measurements.

Abstract: A system for use in a wellbore, comprises a length of casing, a structure that is configured to deform with deformation of the casing, said structure being affixed to the length of casing at substantially the same radial position along the length of casing, and a sensing device that is configured to measure deformation of the structure, said device comprising a plurality of sensors that are distributed with respect to at least one of the length of said structure and the periphery of said structure.

Abstract: A system for use in a wellbore, comprises a length of casing, a structure that is configured to deform with deformation of the casing, said structure being affixed to the length of casing at substantially the same radial position along the length of casing, and a sensing device that is configured to measure deformation of the structure, said device comprising a plurality of sensors that are distributed with respect to at least one of the length of said structure and the periphery of said structure.

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 identifying fluid migration or inflow associated with a wellbore tubular, comprises measuring strain of the wellbore tubular with a system comprising at least one string of interconnected sensors that is arranged such that the sensors are distributed along a length and the circumference of the wellbore tubular; establishing a baseline that is a function of steady state strain measurements within a first time period; and identifying fluid migration or inflow where strain measurements substantially deviate from the baseline within a second time period.

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: Systems and methods for monitoring a well are configured to identify or analyze various issues affecting the well including corrosion, cement quality, inflow, and fluid migration.

Abstract: Integrated fiber optic monitoring techniques for a wellsite are provided. A fiber optic cable is provided with a tubular housing having a channel and a plurality of slots, a plurality of optical fibers may be floatingly positionable in the channel for measuring at least one first wellsite parameter and a plurality of optical fibers fixedly may be positionable in each of the slots for measuring at least one second wellsite parameter. The tubular housing is positionable into a wellbore adjacent a tubing therein. Pairs of the fixed and floating optical fibers may be spliced together to perform Stimulated Brillion measurements.

Abstract: A system (20) for monitoring deformation of a substantially cylindrical casing (14). The system (20) includes at least two strings (22) of interconnected sensors (24) that are wrapped around the casing (14) so as not to intersect one another. At least one of the strings (22) includes a series of at least two segments (S). The series of segments (S) includes a segment (S) arranged at one wrap angle (?) and another segment (S) arranged at a different wrap angle (?).

Abstract: A down-hole tool provided with a transmitter system for inducing a transient electromagnetic field in an earth formation has an induction coil with a number of windings to generate essentially a magnetic dipole field. The number of windings is divided into two or more groups of windings arranged to cooperatively generate the essentially magnetic dipole field when energized. Switching means are arranged to essentially simultaneously terminate the energizing of the groups of windings. The groups of windings are electrically isolated from each other or connected in parallel to each other, at least when the energizing is terminated. A transient electromagnetic field may thus be induced in an earth formation by essentially simultaneously terminating energizing each group of windings by operating the switching means. A transient electromagnetic response signal may be recorded, and used in a method of producing a mineral hydrocarbon fluid.

Abstract: A method for obtaining information about a subsurface formation from acoustic signals that contain information about to the subsurface formation, comprises: providing a fiber optic having a proximal end and a remote end, with the proximal end being coupled to a light source and a proximal photodetector, wherein said fiber optic cable includes randomly spaced impurities and selectively placed Bragg gratings and wherein the fiber optic cable is acoustically coupled to the subsurface formation so as to allow the acoustic signals to affect the physical status of at least one grating: transmitting at least one light pulse into the cable; receiving at the photodetector a first light signal indicative of the physical status of at least one first section of the cable, and outputting at least one item of information to a display.

Abstract: In accordance with the present disclosure, a system and a method are disclosed for measuring a time varying magnetic field. In one aspect, a system comprises a plurality of induction coils arranged to measure the time varying magnetic field using at least one voltage induced in at least one of the induction coils in the plurality of induction coils, a plurality of snubber circuits connected to the plurality of induction coils, each of the snubber circuits of the plurality of snubber circuits arranged to suppress a resonance of a respective one of the induction coils of the plurality of induction coils, and a summing circuit connected to each of the snubber circuits of the plurality of snubber circuits, the summing circuit arranged to sum voltages induced in each of the induction coils in the plurality of induction coils.

Abstract: A method for analyzing fluid proximate an injection well, comprises turning an injector of fluid into the well on or off; determining temperature along a casing of the well during a first time period; and associating a rate of temperature change during the first time period with a fluid.