Method for noninvasive determination of acoustic properties of fluids inside pipes

A method for noninvasively determining the composition of a multiphase fluid comprising oil and water flowing through pipe having a wall and an outside surface, comprising:

• generating an ultrasonic frequency chirp signal using a transmitting transducer in ultrasonic communication with the outside surface of said pipe;
• receiving the generated frequency chirp signal on a receiving transducer in ultrasonic communication with the outside surface of said pipe diametrically opposed to the transmitting transducer after the chirp signal passes through said multiphase fluid, wherein an electrical signal is generated in response thereto;
• receiving the electrical signal;
• cross-correlating the transmitted signal with the received signal, wherein cross-correlation peaks are generated;
• selecting the highest peak which corresponds to the total transmit time of the frequency chirp signal;
• determining the time delay of the frequency chirp signal in the wall of said pipe;
• and
• subtracting the time delay from the total transit time to determine the propagation time of the frequency chirp signal through said multiphase fluid, from which the composition of said multiphase fluid is determined.

A method for noninvasively determining the composition of a multiphase fluid comprising oil and water flowing through pipe having a wall and an outside surface, comprising:

• generating an ultrasonic frequency chirp signal using a transmitting transducer in ultrasonic communication with the outside surface of said pipe;
• receiving the generated frequency chirp signal on a receiving transducer in ultrasonic communication with the outside surface of said pipe diametrically opposed to the transmitting transducer after the chirp signal passes through said multiphase fluid, wherein an electrical signal is generated in response thereto;
• receiving the electrical signal;
• cross-correlating the transmitted signal with the received signal, wherein cross-correlation peaks are generated;
• determining the time between consecutive peaks, wherein the determined time is twice the travel time through said multiphase fluid, from which the composition of said multiphase fluid is determined.

A method for noninvasively determining the composition of a multiphase fluid comprising oil and water flowing through pipe having a wall and an outside surface, comprising:

• generating an ultrasonic frequency chirp signal having a duration shorter than the time the frequency chirp takes to pass through said multiphase fluid using a transmitting transducer in ultrasonic communication with the outside surface of said pipe;
• receiving the generated frequency chirp signal on a receiving transducer in ultrasonic communication with the outside surface of said pipe diametrically opposed to the transmitting transducer after the chirp signal passes through said multiphase fluid, wherein an electrical signal is generated in response thereto;
• receiving the electrical signal;
• transforming the electrical signal using a Short Time Fourier Transform, whereby a plot of the frequency variation of the received frequency chirp as a function of time is generated, and amplitude modulations due to wall resonances appear as individual localized peaks falling on a straight line having a slope;
• performing a least-squares fit of the individual localized peaks with a straight line having the slope;
• determining the intercept on the time axis from which the total transit time is determined;
• determining the time delay of the frequency chirp signal in the wall of said pipe;
• and
• subtracting the time delay from the total transit time to determine the propagation time of the frequency chirp signal through said multiphase fluid, from which the composition of said multiphase fluid is determined.