Apparatus and method for noninvasive particle detection using doppler spectroscopy

摘要

An apparatus and method for noninvasively detecting the presence of solid particulate matter suspended in a fluid flowing through a pipe or an oil and gas wellbore are described. Fluid flowing through a conduit containing the particulate solids is exposed to a fixed frequency (>1 MHz) of ultrasonic vibrations from a transducer attached to the outside of the pipe. The returning Doppler frequency shifted signal derived from the scattering of sound from the moving solid particles is detected by an adjacent transducer. The transmitted signal and the Doppler signal are combined to provide sensitive particulate detection. The magnitude of the signal and the Doppler frequency shift are used to determine the particle size distribution and the velocity of the particles. Measurement of the phase shift between the applied frequency and the detected Doppler shifted may be used to determine the direction of motion of the particles.

主权项

1. An apparatus for noninvasively measuring the velocity and direction of travel of at least one particle suspended in a fluid flowing in a pipe having an axis and a wall, comprising:
a first transducer flush with and in vibrational communication with an outside surface of said pipe at a chosen position along the axis thereof; a signal generator for providing a chosen signal having at least one selected frequency to said first ultrasonic transducer, wherein vibrations are generated in said fluid at least a portion of which vibrations are in the direction of flow of said fluid, and an equal portion thereof are opposite the direction of flow of said fluid; a second transducer flush with and in vibrational communication with an outside surface of said pipe disposed alongside said first transducer at the chosen position along the axis for detecting a scattered vibration signal from said at least one particle; an in-phase and quadrature demodulator for processing the detected scattered signal from said at least one particle; a multichannel analog-to-digital converter a microcontroller; and a digital signal processor controlled by said microcontroller for performing a joint time and frequency analysis of the detected scattered signal from said at least one particle from which a signal amplitude for said at least one particle, and a Doppler frequency shift and a phase shift between the detected scattered signal from said at least one particle and the chosen vibration signal generated by said first transducer, are obtained as a function of time; whereby velocity and direction of travel of said at least one particle are measured.