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ABSTRACT: Onshore and offshore hydrocarbon exploration using SAR data

Insley, Martin W., Adrian Huntley, and John J. Shannon , National Remote Sensing Centre Ltd, Farnborough, United Kingdom

Approximately 75% of frontier exploration is focused on sedimentary basins located in onshore vegetated areas or offshore, causing a dramatic increase in the use of SAR (synthetic aperture radar) data.

The onshore use of SAR data is mainly driven by the absence of suitable cloud-free optical data. It provides a cost effective means for generating mosaics to evaluate regional tectonics of whole countries as well as detailed prospect-scale structural mapping. SAR imagery allows identification of subtle surface features by enhancing topography as well as textural and tonal variations. The availability of stereo Radarsat imagery has greatly improved the use of radar imagery by enabling stereoscopic interpretation; creation of anaglyphs for 3D visualisation; generation of DEMs and production of georeferenced ortho-corrected images. Examples are provided from Sumatra, East Kalimantan, Iran Jaya and Seram to highlight the advantages of combining information derived from both stereo Radarsat and Landsat TM for logistical planning, environmental assessment and geological mapping.

Offshore, SAR imagery provides a rapid and cost effective method of screening large areas for natural oil seeps to help define the limits of a petroleum playfairway. An estimated 10,000 Wide 1 Mode Radarsat scenes are required to provide just single pass coverage of a third of the worlds most prospective offshore basins down to 2000m water depth. Surface slicks appear as dark features on SAR imagery due to the reduction in the backscatter of the radar signal caused by the dampening effect of oil on the capillary waves. Sea surface conditions are therefore critical for seep screening and collection of good quality scenes require careful analysis of the weather conditions prior to image acquisition.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia