METHOD AND APPARATUS FOR HIGH RESOLUTION SOUND SPEED MEASUREMENTS

An apparatus for estimating an influx of a formation fluid into a borehole fluid, the apparatus having: a carrier; an acoustic transducer disposed at the carrier; a first reflector disposed a first distance from the acoustic transducer and defining a first round trip distance; a second reflector disposed a second distance from the acoustic transducer and defining a second round trip distance; and a processor in communication with the acoustic transducer and configured to measure a difference between a first travel time for the acoustic signal traveling the first round trip distance and a second travel time for the acoustic signal traveling the second round trip distance to estimate the influx of the formation fluid; wherein the acoustic transducer, the first reflector, and the second reflector are disposed in the borehole fluid that is in the borehole.