Abstract: Methods for determining a density of a fluid are provided. The method can include passing the fluid through a conduit, measuring a vibration of the conduit by distributed acoustic sensing via a fiber optic cable coupled to the conduit, and generating a vibrational signal indicative of the measured vibration. At least a portion of the vibration of the conduit can be produced by the fluid passing therethrough. The method can also include measuring a temperature of the conduit and generating a temperature signal indicative of the temperature. The method can further include calculating the density of the fluid passing through the conduit by using the vibrational signal and the temperature signal.

Abstract: Methods for determining a density of a fluid are provided. The method can include passing the fluid through a conduit, measuring a vibration of the conduit by distributed acoustic sensing via a fiber optic cable coupled to the conduit, and generating a vibrational signal indicative of the measured vibration. At least a portion of the vibration of the conduit can be produced by the fluid passing therethrough. The method can also include measuring a temperature of the conduit and generating a temperature signal indicative of the temperature. The method can further include calculating the density of the fluid passing through the conduit by using the vibrational signal and the temperature signal.

Abstract: A method of logging a well can include conveying an optical waveguide and at least one signal generator with a conveyance into the well, causing the signal generator to generate at least one signal in the well, and receiving the signal as distributed along the optical waveguide. A well logging system can include a conveyance with an optical waveguide, and at least one signal generator which is conveyed by the conveyance into a well with the optical waveguide, whereby the signal generator generates at least one signal received with the optical waveguide.

Abstract: An illustrative downhole sensing system includes a phase-squeezer assembly, an interferometer with a downhole sensor on the sensing path, and a receiver. The phase squeezer assembly provides a phase-squeezed laser beam, preferably with a squeeze parameter greater than 2. Certain embodiments include a pulse generator that gates the phase-squeezed laser beam to form a sequence of phase-squeezed laser pulses, and may further include a compensator that converts the sequence of pulses into a sequence of double pulses with a slight frequency shift between the pulses in each pair. The interferometer conveys a reference portion of the phase-squeezed laser beam along a reference path and a sensing portion of the phase-squeezed laser beam along a sensing path. A downhole sensor along the sensing path provides the sensing portion of the phase-squeezed laser beam with a measurement-parameter dependent phase shift relative to the reference portion of the phase-squeezed laser beam, which is measured by the receiver.

Abstract: A downhole sensing system includes an optical sensor that provides a light signal with at least one attribute related to a downhole parameter. The system also includes a parametric amplification module that amplifies the light signal using squeezed or entangled light for internal mode input. The system also includes a processing unit that determines a value for the downhole parameter based on the amplified light signal.

Abstract: Various systems and methods for implementing and using a downhole all-optical magnetometer include downhole all-optical magnetometer sensor, including optical receiving ports that receive light pulses, a depolarizer that depolarizes received light pulses, and a polarizer that polarizes depolarized light pulses from the depolarizer. The sensor further includes a vapor-filled cell through which polarized light pulses from the polarizer are directed, wherein interactions between vapor and a magnetic field within the vapor-filled cell alter at least some of the polarized light pulses, and an optical transmitting port that directs altered light pulses from the vapor-filled cell out of the sensor.

Abstract: A method and device for monitoring oil field operations with a fiber optic distributed acoustic sensor (DAS) that uses a continuous wave laser light source and modulates the continuous wave output of the laser light source with pseudo-random binary sequence codes.

Abstract: An illustrative downhole sensing system includes a phase-squeezer assembly, an interferometer with a downhole sensor on the sensing path, and a receiver. The phase squeezer assembly provides a phase-squeezed laser beam, preferably with a squeeze parameter greater than 2. Certain embodiments include a pulse generator that gates the phase-squeezed laser beam to form a sequence of phase-squeezed laser pulses, and may further include a compensator that converts the sequence of pulses into a sequence of double pulses with a slight frequency shift between the pulses in each pair. The interferometer conveys a reference portion of the phase-squeezed laser beam along a reference path and a sensing portion of the phase-squeezed laser beam along a sensing path. A downhole sensor along the sensing path provides the sensing portion of the phase-squeezed laser beam with a measurement-parameter dependent phase shift relative to the reference portion of the phase-squeezed laser beam, which is measured by the receiver.

Abstract: A downhole sensing system includes an optical sensor that provides a light signal with at least one attribute related to a downhole parameter. The system also includes a parametric amplification module that amplifies the light signal using squeezed or entangled light for internal mode input. The system also includes a processing unit that determines a value for the downhole parameter based on the amplified light signal.

Abstract: A method of logging a well can include conveying an optical waveguide and at least one signal generator with a conveyance into the well, causing the signal generator to generate at least one signal in the well, and receiving the signal as distributed along the optical waveguide. A well logging system can include a conveyance with an optical waveguide, and at least one signal generator which is conveyed by the conveyance into a well with the optical waveguide, whereby the signal generator generates at least one signal received with the optical waveguide.

Abstract: A well flow velocity measurement method can include transmitting an acoustic signal through at least one fluid composition in a well, detecting velocities of the acoustic signal in both opposite directions along an optical waveguide in the well, the optical waveguide being included in a distributed acoustic sensing system, and determining an acoustic velocity in the fluid composition based on the velocities of the acoustic signal. Another well flow velocity measurement method can include propagating at least one pressure pulse through at least one fluid composition in a well, detecting a velocity of the pressure pulse along an optical waveguide in the well, the optical waveguide being included in a distributed acoustic sensing system, and determining an acoustic velocity in the fluid composition based on the velocity of the pressure pulse.

Abstract: A method of generating an acoustic signal in a subterranean well can include converting optical energy to acoustic energy downhole, thereby transmitting the acoustic signal through a downhole environment. A well system can include an optical acoustic transducer disposed in the well and coupled to an optical waveguide in the well, whereby the transducer converts optical energy transmitted via the optical waveguide to acoustic energy. An optical acoustic transducer for use in a subterranean well can include various means for converting optical energy transmitted via an optical waveguide to acoustic energy in the well.

Abstract: A method of calibrating a distributed acoustic sensing system can include receiving predetermined acoustic signals along acoustic sensors distributed proximate a well, and calibrating the system based on the received acoustic signals. A method of calibrating an optical distributed acoustic sensing system can include displacing an acoustic source along an optical waveguide positioned proximate a well, transmitting predetermined acoustic signals from the acoustic source, receiving the acoustic signals with the waveguide, and calibrating the system based on the received acoustic signals. A well system can include a distributed acoustic sensing system including an optical waveguide installed in a well, and a backscattered light detection and analysis device, and at least one acoustic source which transmits predetermined acoustic signals at spaced apart locations along the waveguide. The device compensates an output of the system based on the acoustic signals as received at the locations along the waveguide.

Abstract: Various systems and methods for implementing and using a downhole all-optical magnetometer include downhole all-optical magnetometer sensor, including optical receiving ports that receive light pulses, a depolarizer that depolarizes received light pulses, and a polarizer that polarizes depolarized light pulses from the depolarizer. The sensor further includes a vapor-filled cell through which polarized light pulses from the polarizer are directed, wherein interactions between vapor and a magnetic field within the vapor-filled cell alter at least some of the polarized light pulses, and an optical transmitting port that directs altered light pulses from the vapor-filled cell out of the sensor.