Regional 3-D Geomorphic Features – Effective Guides for Hydrocarbon Exploration

John R. Everett and Ronald J. Staskowski
Earth Satellite Corporation, Rockville, MD

Merging digital elevation models (DEMs) from the Shuttle Radar Topography Mission (SRTM) with satellite imagery makes large-scale geomorphic features obvious. In some areas, these features are powerful guides for petroleum exploration.

Merged Landsat-7 satellite data and SRTM-3 DEM's of the Texas Gulf Coast reveal 17 prominent northwest-trending topographic features that extend more than 100 miles inland from the coast. Straight segments of rivers and streams, elongate topographic lows, and aligned saddles in the generally northeast-trending cuestas of more resistant Tertiary units mark these features. It appears there is no significant vertical displacement across these features.

Several authors have noted a northwest-oriented pattern in the stacked delta and channel-filled sand systems of the Rockdale, Queen City, Yegua, Fayette, and Fleming stratigraphic units. Other authors have noted favorable zones of fracturing in the Austin Chalk and Buda Limestone. Evidence of these features is present in rocks as old as Jurassic. Based on geomorphic and geologic evidence, these features appear to be fracture zones. There is a strong coincidence between these northwest-trending zones, oil and gas fields, and the location of wells with high IP rates.

These features may be the surface manifestation of transform faults related to the opening of the Gulf of Mexico. The intersection of these features with coast parallel, generally northeast-trending, normal faults and extensional fracture zones are lucrative exploration areas for fracture porosity/permeability targets in Cretaceous limestones and Upper Cretaceous and Tertiary clastic units.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005