The Contribution of Earth Observation Data to Frontier Exploration

Earth Observation technology is increasingly being used to assist hydrocarbon exploration in frontier areas. Both medium resolution optical and radar satellite imagery have a role to play in the regional assessment and appraisal of surface geological structure and stratigraphy and the identification of natural oil seeps present on lakes and offshore areas. The objective of this paper is to review how this geological and hydrocarbon seep information can contribute to both onshore and offshore exploration, focusing on the East Africa Rift System (EARS) and the more established Kurdistan and Eastern Mediterranean areas.

Two main remote sensing datasets are used in this study for geological interpretation; orthorectified Landsat 7 ETM + mosaics in a 742 (RGB) pseudo-colour composite band combination with a resolution of 15m and the Shuttle Radar Topographic Mission (SRTM) 90m Digital Elevation Model (DEM). Landsat 7 ETM+ satellite imagery is the standard imagery dataset used for regional scale geological mapping down to 1:50,000 scale, typically in a 742 (RGB) band combination. Utilizing the Short Wave InfraRed (SWIR), this 742 band combination offers maximum lithological discrimination.

Identifying seeps from radar imagery is an established method often applied to screen offshore basins based on the observing the variation in return signal and noting any anomalous areas caused by the dampening effect the oil has on wave heights. By collecting imagery from multiple dates and by studying the morphology of the slick, a greater level of confidence can be assigned to the features, reducing the likelihood that an area of pollution or local weather conditions are being observed.

The EARS study has identified evidence of the main rifting events; the Permian to Jurassic, Cretaceous and Tertiary-Quaternary, which have defined its current morphology, and how the contrasting geological characteristics of the Eastern and Western Braches may have a corresponding influence on prospectivity. By regionally evaluating the Eastern Mediterranean, using satellite imagery combined with existing gravity, bathymetry and magnetic data, the spatial distribution of natural oil seeps is explored. Over Kurdistan, a detailed understanding of the variation is tectonic characteristics across the fold belt have allowed an increased understanding of the surface geology with the identification of previously unmapped structures.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California