Gas hydrate is solid solution which is formed when gas
molecules were trapped in crystal lattices that is
formed by water molecules at low temperature and
high pressure. So that gas hydrate commonly found in
permafrost and deep water ocean along continental
margin. In Indonesia, gas hydrate can be found in deep
ocean along subduction zone, such as Sunda Arc Basin
and X Basin. X Basin is located at western Sulawesi.
The presence of gas hydrate in nature can be
represented by Bottom Simulating Reflector (BSR) on
seismic section. BSR occur if gas hydrate bearing
sediment and gas/water bearing sediment below has a
negative contrast acoustic impedance. Those negative
value is caused by the increasing of P- and S-wave
velocity and density in gas hydrate bearing sediment.
3D seismic acquisition has been conducted in X
Basin. The data was processed so gas hydrate in this
basin can be identified and characterized. Firstly, the
preliminary seismic data processing was conducted to
produce a good quality seismic section/gathers.
Secondly, this seismic section/gathers are developed
by using advance seismic processing, such as seismic
attributes, and AVO methods. Unfortunately, there is
no well log data for this study, so the identification and characterization has been done as an estimation
without an accurate validation.
Seismic section/gathers in this study give
information about the presence of gas hydrate. BSRs
can be seen clearly almost in every along the crossline
direction and they can be used as preliminary
identification. Furthermore, RMS amplitude slice
section and apparent polarity resulted in the same way.
Through the seismic attribute method, gas hydrate
bearing sediment velocity can be estimated around
2000 m/s with 100 m of thickness.