Some embodiments of the inventive subject matter improve techniques for measuring downhole attributes. A method for determining a flow rate of a fluid includes positioning a tubular within a wellbore formed in a subsurface formation, wherein a flow of fluid is to move through the tubular. An orifice plate is positioned in the tubular. The orifice plate is movable between a first position and a second position to alter a flow area of the flow of fluid moving through the tubular. The method includes detecting a change in a downhole attribute that changes in response to the alteration of the flow area of the flow of fluid. Sensors positioned within or in communication with an interior of the tubular can detect the change in the downhole attribute. The method further includes determining a flow rate of the flow of fluid based on the detected change in the downhole attribute.

Disclosed are systems and methods for processing broadband acoustic signals acquired by a plurality of acoustic sensors, using an array-signal-processing technique to compute fused-signal maps in the frequency domain for a plurality of frequency bins. In accordance with various embodiments, the fused-signal maps are combined across the frequency bins, with respective weightings that are based on eigenvalues of covariance matrices computed for the plurality of frequency bins. The combined maps can be used to locate an acoustic source in a wellbore.

Disclosed are systems and methods for processing broadband acoustic signals acquired by a plurality of acoustic sensors, using an array-signal-processing technique to compute fused-signal maps in the frequency domain for a plurality of frequency bins. In accordance with various embodiments, the fused-signal maps are combined across the frequency bins, with respective weightings that are based on eigenvalues of covariance matrices computed for the plurality of frequency bins. The combined maps can be used to locate an acoustic source in a wellbore.

The disclosure provides an acoustic logging device comprising a first tubular member comprising a plurality of grooves disposed on an exterior of the first tubular member. The acoustic logging device further comprises a ring transmitter module disposed around an exterior of the first tubular member, which comprises a piezoelectric (PZT) ring transmitter, a transmitter sleeve, wherein the PZT ring transmitter is disposed within the transmitter sleeve, and a cage, wherein the transmitter sleeve is disposed between the cage and the exterior of the first tubular member, wherein the transmitter sleeve is disposed over the plurality of grooves. The acoustic logging device further comprises a plurality of dual bender transmitters, wherein there is a gap disposed the plurality of dual bender transmitters in the exterior of the first tubular member, wherein there is an array of holes connecting each of the gaps together and providing fluid communication between the gaps.

The disclosure provides an acoustic logging device comprising a first tubular member comprising a plurality of grooves disposed on an exterior of the first tubular member. The acoustic logging device further comprises a ring transmitter module disposed around an exterior of the first tubular member, which comprises a piezoelectric (PZT) ring transmitter, a transmitter sleeve, wherein the PZT ring transmitter is disposed within the transmitter sleeve, and a cage, wherein the transmitter sleeve is disposed between the cage and the exterior of the first tubular member, wherein the transmitter sleeve is disposed over the plurality of grooves. The acoustic logging device further comprises a plurality of dual bender transmitters, wherein there is a gap disposed the plurality of dual bender transmitters in the exterior of the first tubular member, wherein there is an array of holes connecting each of the gaps together and providing fluid communication between the gaps.

A monitoring system includes a flow line, an optical fiber coupled to the flow line, and a receiver coupled to an end of the optical fiber. The receiver is configured to detect at least one acoustic signal from the optical fiber. In addition, the monitoring system includes processor unit to detect a flow obstruction within the flow line based on the acoustic signal.

A monitoring system includes a flow line, an optical fiber coupled to the flow line, and a receiver coupled to an end of the optical fiber. The receiver is configured to detect at least one acoustic signal from the optical fiber. In addition, the monitoring system includes processor unit to detect a flow obstruction within the flow line based on the acoustic signal.

A communication system that is positionable in a wellbore can include a first transceiver positioned externally to a casing string. The first transceiver can be operable to detect a presence or an absence of a surface wave; determine a location of a fluid in the wellbore based on the presence or the absence of the surface wave; and transmit data indicative of the location to a second transceiver. The surface wave can include an electromagnetic wave that has a magnetic field or an electric field that is non-transverse to a direction of propagation of the surface wave. The communication system can also include the second transceiver, which can be positioned externally the casing string and operable to receive the data.

Described herein are tools, systems, and methods for detecting, classifying, and/or quantifying underground fluid flows based on acoustic signals emanating therefrom, using a plurality of acoustic sensors disposed in the wellbore in conjunction with array signal processing and systematic feature-based classification and estimation methods.

A flowback system and method employ a flowback model that characterizes fluid properties and rock mechanical properties of the reservoir during flowback in conjunction with measurement and analysis of chemistry and solids production with respect to the flowback fluid in order to maximize efficiency during the flowback operations, while mitigating formation damage and hydraulic fracture conductivity degradation. The methodology can define a safe drawdown operating zone for conducting flowback operations.