Abstract: Seismic sensor systems and sensor station topologies, as well as corresponding cable and sensor station components, manufacturing and deployment techniques are provided. For some embodiments, networks of optical ocean bottom seismic (OBS) stations are provided, in which sensor stations are efficiently deployed in a modular fashion as series of array cable modules deployed along a multi-fiber cable.

Abstract: Seismic sensor systems and sensor station topologies, as well as corresponding cable and sensor station components, manufacturing and deployment techniques are provided. For some embodiments, networks of optical ocean bottom seismic (OBS) stations are provided, in which sensor stations are efficiently deployed in a modular fashion as series of array cable modules deployed along a multi-fiber cable.

Abstract: Accelerometers for determining acceleration and methods of fabricating an accelerometer are disclosed. In one embodiment, the accelerometer includes a frame, a mass movably suspended on the frame, a fixed element having a rounded surface that does not move with respect to the frame, a movable element having a rounded surface that moves with the mass, and a sensing coil of optical waveguide wrapped around the rounded surfaces to detect movement of the mass in response to acceleration based on interferometric sensing of a change in length of the sensing coil. A method of fabricating the accelerometer includes suspending the mass in the frame and wrapping the optical waveguide around the rounded surfaces. Sensitivity and low fabrication cost of the accelerometers enables their use for integration within an ocean bottom seismic cable. Further, the accelerometer may be an in-line or a cross-line accelerometer depending on the arrangement within the frame.

Abstract: Seismic sensor systems and sensor station topologies, as well as corresponding cable and sensor station components, manufacturing and deployment techniques are provided. For some embodiments, networks of optical ocean bottom seismic (OBS) stations are provided, in which sensor stations are efficiently deployed in a modular fashion as series of array cable modules deployed along a multi-fiber cable.

Abstract: A seismic sensor station includes a housing containing a fiber optic hydrophone and a fiber optic accelerometer that can both be made from a single length of optical fiber arranged inside the housing. The fiber optic accelerometer is arranged in a liquid/oil filled compartment of the housing for dampening of mechanical resonances in the accelerometer due to mechanical disturbances and pressure fluctuations.

Abstract: Storage and installation systems used in storage, deployment or retrieval of a seismic cable array include one or more baskets adapted for being stacked. Each basket is dimensioned to allocate, in an ordered arrangement, a number of seismic stations interconnected by sections of seismic cable. Corresponding methods of storing a seismic cable and deploying/retrieving a seismic cable are based on the use of baskets having an ordered arrangement of seismic stations.

Abstract: Accelerometers for determining acceleration and methods of fabricating an accelerometer are disclosed. In one embodiment, the accelerometer includes a frame, a mass movably suspended on the frame, a fixed element having a rounded surface that does not move with respect to the frame, a movable element having a rounded surface that moves with the mass, and a sensing coil of optical waveguide wrapped around the rounded surfaces to detect movement of the mass in response to acceleration based on interferometric sensing of a change in length of the sensing coil. A method of fabricating the accelerometer includes suspending the mass in the frame and wrapping the optical waveguide around the rounded surfaces. Sensitivity and low fabrication cost of the accelerometers enables their use for integration within an ocean bottom seismic cable. Further, the accelerometer may be an in-line or a cross-line accelerometer depending on the arrangement within the frame.

Abstract: A clamp mechanism for actively coupling an in-well seismic station to the casing of a well is disclosed. The clamp mechanism is capable of associating a sensor to production tubing for deployment in the well and is capable of actively coupling the sensor to the casing of the well. The clamp mechanism includes a body capable of being coupled to the deployment member. A carrier mechanism is attached to the sensor and positions adjacent the body. A release mechanism releases the carrier mechanism when subjected to a predetermined pressure in the well or when subjected to fluid in the well for a predetermined amount of time. A biasing mechanism is disposed between the body and the carrier mechanism and displaces the carrier mechanism with attached sensor towards the surface of the casing when released. A guiding mechanism guides the displacement of the carrier mechanism towards the surface of the casing.

Abstract: A dome-shaped chemical sensing probe comprises an optical fiber or may be mounted on an optical fiber. The probe has a chemically sensitive measuring material which exhibits a change in volume and/or a change in refractive index in the presence of a given chemical. The change in volume and/or refractive index gives a change in an optical path length through the probe which can be measured interferometrically.

Abstract: Methods and apparatus for cable termination and sensor integration at a sensor station within an ocean bottom seismic (OBS) cable array are disclosed. The sensor stations include a housing for various sensor components. Additionally, the sensor stations can accommodate an excess length of any data transmission members which may not be cut at the sensor station while enabling connection of one or more cut data transmission members with the sensor components. The sensor stations further manage any strength elements of the cable array.

Abstract: An apparatus and method for transporting, deploring, and retrieving an array is disclosed. The array has a plurality of nodes interconnected by sections of cable and can be transported, deployed, and retrieved with the apparatus and method of the present invention. The apparatus includes a plurality of first divisions and a plurality of second divisions. The first divisions have first portions or holders capable of individually accommodating the nodes. The second divisions are alternatingly positioned adjacent the first divisions. The second divisions have second portions or surfaces capable of individually accommodating the sections of cable. The first and second divisions can be integral portions of the apparatus, can be separate members positioned on the apparatus, or can be used with a standard cable drum. Preferably, the second divisions can be rotated relative to the first divisions to tightly wind and easily unwind the sections of cable.

Abstract: A highly sensitive accelerometer for determining the acceleration of a structure includes a mass within a housing suspended by opposing support members. The support members are alternately wound around a pair of fixed mandrels and the mass in a push pull arrangement. At least a portion of one of the support members comprises a transducer capable measuring the displacement of the mass within the housing. An embodiment of the invention employs optical fiber coils as the support members for use in interferometric sensing processes. Arrays of such interferometer based accelerometers may be multiplexed using known techniques.

Abstract: A body compatible fiber optic sensor probe for invasive medical use is provided. The probe includes at least one sensing location at which the fiber is configured to provide at least one detectable changeable optical property responsive to strain within the fiber, and at least one sensing element which undergoes a volumetric change in response to an in body parameter to be sensed. The sensing element is coupled to the fiber in such a way that the volumetric change induces strain within the fiber so as to vary the detectable optical property or properties.

Abstract: The present invention generally relates to an apparatus and method for seismic monitoring. In one aspect, an apparatus for acoustically coupling a sensor mechanism to a surface in a wellbore is provided. The apparatus includes a mandrel disposable in a tubing string. The apparatus further includes a carrier member disposed on the mandrel, the carrier member axially adjustable relative to the mandrel. The apparatus also includes at least one sensor mounted on the carrier member, the at least one sensor connected to the surface of the well via a cable line and a deployment assembly disposed on the carrier member for coupling the at least one sensor to the surface of the well. In another aspect, a method for acoustically coupling a sensor mechanism to a surface of a wellbore is provided.

Abstract: Accelerometers for determining acceleration and methods of fabricating an accelerometer are disclosed. In one embodiment, the accelerometer includes a frame, a mass movably suspended on the frame, a fixed element having a rounded surface that does not move with respect to the frame, a movable element having a rounded surface that moves with the mass, and a sensing coil of optical waveguide wrapped around the rounded surfaces to detect movement of the mass in response to acceleration based on interferometric sensing of a change in length of the sensing coil. A method of fabricating the accelerometer includes suspending the mass in the frame and wrapping the optical waveguide around the rounded surfaces. Sensitivity and low fabrication cost of the accelerometers enables their use for integration within an ocean bottom seismic cable. Further, the accelerometer may be an in-line or a cross-line accelerometer depending on the arrangement within the frame.

Abstract: A highly sensitive accelerometer for determining the acceleration of a structure includes a mass within a housing rotationally supported by a hinge and opposing support members. The support members are alternately wound around a fixed mandrel and the mass in a pendulum arrangement. At least a portion of one of the support members comprises a transducer capable measuring the rotation of the mass within the housing. An embodiment of the invention employs optical fiber coils as support members for use in interferometric sensing processes. Arrays of such interferometer based accelerometers maybe multiplexed using WDM or similar methods.

Abstract: A multiple component mechanism for housing one or more fiber optic based sensors and one or more fiber organizers and other devices for the sensors is disclosed. The mechanism includes a splice component and a sensor component, which are hermetically sealed. The sensor and splice components include substantially tubular bodies having lids welded to the ends. The fiber organizer and other devices are installed in the cylindrical splice component. The one or more sensors are installed in the tubular body of the sensor component with wedging devices. In one embodiment, the sensor component is acoustically decoupled from the splice component by a tube welded to the lids of the components. The tube communicates optical fiber from the fiber organizer to the one or more sensors.

Abstract: A highly sensitive accelerometer for determining the acceleration of a structure includes a mass within a housing suspended by opposing support members. The support members are alternately wound around a pair of fixed mandrels and the mass in a push pull arrangement. At least a portion of one of the support members comprises a transducer capable measuring the displacement of the mass within the housing. An embodiment of the invention employs optical fiber coils as the support members for use in interferometric sensing processes. Arrays of such interferometer based accelerometers may be multiplexed using known techniques.

Abstract: The present invention generally relates to an apparatus and method for seismic monitoring. In one aspect, an apparatus for acoustically coupling a sensor mechanism to a surface in a wellbore is provided. The apparatus includes a mandrel disposable in a tubing string. The apparatus further includes a carrier member disposed on the mandrel, the carrier member axially adjustable relative to the mandrel. The apparatus also includes at least one sensor mounted on the carrier member, the at least one sensor connected to the surface of the well via a cable line and a deployment assembly disposed on the carrier member for coupling the at least one sensor to the surface of the well. In another aspect, a method for acoustically coupling a sensor mechanism to a surface of a wellbore is provided.

Abstract: An acoustic sensor, such as a hydrophone, is deployable in a fluidic media having high temperature, high pressure, and/or potentially caustic chemicals. The hydrophone includes a housing filled with an internal fluid and containing a sensing mandrel. The sensing mandrel senses the acoustic pressure transmitted to the internal fluid through a diaphragm. The sensing mandrel preferably includes a polymer tubular mandrel having a coil of optical fiber wound and bonded to its outer surface. The sensing mandrel can be suspended within the housing instead of being rigidly attached thereto. To relieve pressure created by thermal expansion of the internal fluid, the flexible diaphragm, a filler member, a pressure compensator, or combinations thereof can be used. The filler member is mounted in the hydrophone and reduces the amount of internal fluid required in the housing. The compensator may be a bellows or a buffer tube.