Ultrasonic logging methods and apparatus for measuring cement and casing properties using acoustic echoes

A method and apparatus for measuring parameters of a borehole using an acoustic logging system. By transmitting a high frequency acoustic signal essentially perpendicular to the major axis of a borehole casing using a transducer, the high frequency acoustic signal may produce one or more acoustic echoes. By receiving and analyzing a first acoustic echo from an inner wall of the borehole casing and at least one second acoustic echo from a back wall of the borehole casing, borehole parameters such as the impedance of the casing cement and the thickness of thicker borehole casings, up to and greater than 1 inch, may be determined.