Apparatus and method for noninvasive particle detection using Doppler spectroscopy

摘要

An apparatus and method for detecting the presence of solid particulates suspended in a fluid flowing through a pipe or an oil and gas wellbore are described. A volume of fluid flowing through a conduit containing the particulate solids is exposed to a fixed frequency 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 a transducer. The high frequencies used are above external and ambient noise present in production locations, and sound transmission through the conduit wall is maximized by selecting frequencies that correspond to the thickness mode resonance of the wall. 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.