Improved
Identification and Characterization of Deepwater Thermogenic
Hydrocarbon Macro-Seepage Using High-Resolution AUV Geophysical Data
Samuels, Bruce. M1, Harry
Dembicki2 (1) C & C Technologies, Lafayette, LA (2) Anadarko
Petroleum Corp,
The search for seafloor hydrocarbon
macro-seepage is an important part of deepwater exploration programs. Detecting
thermogenic hydrocarbons at the seafloor provides
strong evidence for the presence of a working petroleum system in the
subsurface. This knowledge can substantially reduce the risk in drilling
expensive deepwater wells.
Using conventional seismic data to detect
potential seep features is often inadequate. 2-D data is limited to imaging the
seafloor directly along the seismic grid lines. Because hydrocarbon seeps are
often small features, they are not always easily recognized in seafloor
extractions from 3-D data due to lack of resolution. As such, many seep
features may be easily overlooked when relying on these data.
In contrast, AUV geophysical surveys
utilizing detailed bathymetry, side scan sonar, and sub-bottom acoustic
profiling allow for high-resolution seafloor and near-seafloor
characterization. The morphologies of seafloor features can be directly tied to
perturbations of sub-bottom sediments below each feature providing insight into
the presence of potential hydrocarbon seeps. This can then be related to deeper
structures and faults imaged on conventional seismic establishing the link
between subsurface reservoirs, migration pathways, and potential seafloor
seeps.
This study shows how higher resolution
AUV geophysical data was an extremely valuable tool for selecting coring
locations in the
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California