INVESTIGATION A CASE HISTORY OF YELLOW FIN AND DIFFERENTIATION OF SAND AND GRAVEL ON SEAFLOOR BY SIDE SCAN SONAR IMAGES

8th International Scientific Conference - SGEM2008, www.sgem.org, SGEM2008 Conference Proceedings/ ISBN: 954-918181-2, June 16-20, 2008, Vol. 2, 399-406 pp

ABSTRACT

Bathymetric mapping is the first step in any underwater and sea bed investigation,
especially for petroleum exploration. In most we face with a complex of sand and gravel
covering the bottom of the sea. Differentiate these two type of seafloor covering
material is the case of many research in offshore exploration. In this article We
investigated a practical case history to define and show the differences of sand and
gravel in their images. The images were obtained by the Yellow-Fin side scan sonar
instrument and processed with related software, yellow-fin. The sound transmitted by
the DSL-120 kHz instrument travels to the seafloor, bounces off of the seafloor, returns
to the instrument, and is recorded. The intensity or strength of the returning acoustic
signal is controlled primarily by the slope of the seafloor and what the seafloor is made
of. The strength of the sound recorded by the side-scan sonar instrument converted to
shades of gray. A very strong return is white; a very weak return is black. The return is
stronger if the seafloor is made of bare rock. The strength of the return is much lower if
the seafloor is covered by mud or sand. In this case history the gravels and sands were
differentiated as well, the bathymetric map of the part of the seabed which scanned was
also obtained.

Keywords: Side Scan sonar, Bathymetry, Echo sounding, Yellow-fin instrument & software.