Methods for processing ultrasonic signal data to evaluate subsurface properties
and tool orientation. Acoustic signals are transmitted into a plurality of azimuthal
borehole positions. Formation echo signal transit time distributions are then determined
in a plurality of azimuthal sectors for the acoustic signals. Front face echo signal
transit times are also measured and farther-mode and closer-mode transit times
are determined for the distribution of formation echo signals. Farther and closer
tool standoffs are determined for the azimuthal sectors and a borehole diameter
is determined from a summation including standoffs in opposing sectors. The standoffs
are also used to determine a preferential tool position.
