Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for monitoring slug flow in subterranean wells. In one aspect, a method includes at a time instant, transmitting an acoustic signal across a cross-section of a pipeline flowing multiphase fluid including gaseous fluid and liquid fluid, wherein a portion of the acoustic signal is carried through the cross-section of the pipeline by the multiphase fluid and determining, at the time instant, a first quantity of the gaseous fluid and a second quantity of the liquid fluid passing the cross-section of the pipeline based, in part, on an energy of the portion of the acoustic signal carried through the cross-section and at least a portion of a total energy of the transmitted acoustic signal.

A method for detecting a property of a liquid medium comprises generating an ultrasonic pulse, receiving a first echo and a second echo of the ultrasonic pulse transmitted through the liquid medium, and generating a first amplitude signal for the first echo and a second amplitude signal for the second echo. The method includes calculating an amplitude signal ratio between the first amplitude signal and the second amplitude signal and determining a property signal representing the property of the liquid medium.

To detect air in a fluid delivery line of an infusion system, infusion fluid is pumped through a fluid delivery line adjacent to at least one sensor. A signal is transmitted and received using the at least one sensor into and from the fluid delivery line. The at least one sensor is operated, using at least one processor, at a modified frequency which is different than a resonant frequency of the at least one sensor to reduce an amplitude of an output of the signal transmitted from the at least one sensor to a level which is lower than a saturation level of the analog-to-digital converter to avoid over-saturating the analog-to-digital converter. The signal received by the at least one sensor is converted from analog to digital using an analog-to-digital converter. The at least one processor determines whether air is in the fluid delivery line based on the converted digital signal.

A system includes a probe, a processor, and a bubble detector. The probe is configured for insertion into a lumen of a patient and is coupled to an irrigation pump. The processor is configured to control delivery of irrigation fluid to the probe by turning on and controlling the irrigation pump. The bubble detector is coupled to a proximal portion of the probe. In response to the irrigation pump being turned on, the bubble detector is configured to automatically start detection of gas bubbles in the irrigated fluid, and transmit fail-safe signals indicating fail-safe bubble detection is operational. The processor is further configured to monitor the fail-safe signals and, in absence of fail-safe signals, to automatically disable delivery of the irrigation fluid.

A circuit for detecting air, a related system, and a related method are provided. The circuit for detecting air includes a receiver connection and an air-detection circuit. The receiver connection is configured to provide a receiver signal. The air-detection circuit is in operative communication with the receiver connection to process the receiver signal to generate a processed signal corresponding to detected air. The air-detection circuit includes one or more active-rectifying elements configured to actively rectify the receiver signal to provide the processed signal.

A system for measuring a rising velocity and a deformation of a bubble in a viscous fluid includes a sample cell configured to hold a viscous fluid, a variable-diameter syringe provided at a bottom of the sample cell and configured to generate a bubble in the viscous fluid, two ultrasonic transmitting and receiving transducers arranged at different heights of the sample cell and configured to transmit first ultrasonic signals to the viscous fluid and receive second ultrasonic signals reflected by the bubble, and a host computer configured to analyze time-domain information of the second ultrasonic signals received by the two ultrasonic transmitting and receiving transducers, calculate the rising velocity of the bubble, build a mathematical model about a bubble size and a reflected sound pressure, analyze frequency-domain information of the second ultrasonic signals received by the two ultrasonic transmitting and receiving transducers, and calculate the deformation of the bubble.

Systems and methods for material composition detection includes a vessel containing a quantity of a fluid composition therein which has at least a first and second fluids. At least one acoustic transducer is positioned on an exterior sidewall of the vessel. A computerized device has a processor and is in communication with the acoustic transducer. A metric of a property of the first fluid is determined based on a first signal of the acoustic transducer. A metric of a property of the second fluid is determined based on a second signal of the acoustic transducer. A metric of a property of the fluid composition at a point in time is determined based on the metrics of the first and second fluids, and at least a determinable volume of at least a portion of the vessel. A material identity of the fluid composition is determined at the point in time.

Embodiments of the invention provide a “tool-kit” of processing techniques which can be employed in different combinations depending on the circumstances. For example, flow speed can be found using eddy tracking techniques, or by using speed of sound measurements. Moreover, composition can be found by using speed of sound measurements and also by looking for turning points in the k-w curves, particularly in stratified multi-phase flows. Different combinations of the embodiments can therefore be put together to provide further embodiments, to meet particular flow sensing requirements, both on the surface and downhole. Once the flow speed is known, then at least in the case of a single phase flow, the flow speed can be multiplied by the interior cross-sectional area of the pipe to obtain the flow rate. The mass flow rate can then be obtained if the density of the fluid is known, once the composition has been determined.

A detector comprises an optical parametric oscillator having a non-linear material adapted to convert via a parametric process pump light into down converted light of two different wavelengths, the first wavelength being longer than the second wavelength. The non-linear material is provided in a down converted wave cavity arranged to resonate only one of the first or second wavelengths. The detector comprises means for modulating light in the down converted wave cavity to induce an acoustic or pressure wave caused by absorption of the resonant one of the first and second wavelengths. The detector further comprises means located in the down-converted wave cavity for detecting the acoustic or pressure wave. The detector may be used for detecting or sensing very low levels of a fluid, for example a gas such as ethane.

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for monitoring slug flow in subterranean wells. In one aspect, a method includes at a time instant, transmitting an acoustic signal across a cross-section of a pipeline flowing multiphase fluid including gaseous fluid and liquid fluid, wherein a portion of the acoustic signal is carried through the cross-section of the pipeline by the multiphase fluid and determining, at the time instant, a first quantity of the gaseous fluid and a second quantity of the liquid fluid passing the cross-section of the pipeline based, in part, on an energy of the portion of the acoustic signal carried through the cross-section and at least a portion of a total energy of the transmitted acoustic signal.