Page 272 - Geochemical Remote Sensing of The Sub-Surface

Aerospace detection of hydrocarbon-induced alteration 245

anomaly result from an active hydrocarbon seep or a palaeoseep? Finally, if the
anomaly at the surface is to be related to a drilling objective at depth, does the anomaly
result from mainly vertical migration or does the migration path follow a more complex
route?
The laboratory and field spectra of hydrocarbon-induced alteration products have
been characterised, but the spectral resolution of MSS and TM are not high enough to
be compared with the laboratory or field spectra. Although there has been some success
in the detection of vegetation stress and alteration of mineral assemblages, the broad
bandwidths of existing satellite platforms cannot characterise all the absorption features
caused by hydrocarbon microseepage, regardless of the type of enhancements employed
or the type of information extraction method applied. In short, high spectral resolution
imaging data are needed for the recognition of the hydrocarbon-induced alterations and
related vegetation changes.
Remote sensing for direct detection of hydrocarbon microseepage holds great
promise as an airborne geochemistry-biogeochemistry method that can complement
seismic exploration by helping to recognise marginal and submarginal low relief
structural prospects and stratigraphic traps. Through improved understanding of
hydrocarbon microseepage and its surface manifestations along with imaging data of
higher spatial and spectral resolution, we have a better chance to delineate the surface
anomalies associated with subsurface hydrocarbon reservoirs.