Abstract: Geological and Environmental Remote Sensing for International Petroleum Operations

James M. Ellis

Remote sensing allows the petroleum industry to make better and quicker interpretations of geological and environmental conditions in areas of present and future operations. Often remote sensing (including aerial photographs) is required because existing maps are out-of-date, too small of scale, or provide only limited information. Implementing remote sensing can lead to lower project costs and reduced risk.

The same satellite and airborne data can be used effectively for both geological and environmental applications. For example, earth scientists can interpret new lithologic, structural, and geomorphic information from near-infrared and radar imagery in terrains as diverse as barren desert and tropical jungle. Environmental applications with these and other imagery include establishing baselines, assessing impact by documenting changes through time, and mapping land-use, habitat, and vegetation. Higher resolution sensors provide an up-to-date overview of onshore and offshore petroleum facilities, whereas sensors capable of oblique viewing can be used to generate topographic maps.

Geological application in Yemen involved merging Landsat TM and SPOT imagery to obtain exceptional lithologic discrimination. Seismic planning and gravity modeling were significantly improved by digitally draping this enhanced color image over a SPOT/GPS-derived digital elevation model (DEM). This DEM was used to digitally create artificial parallax, permitting stereoscopic interpretation and quantitative determination of structural data (strike, dip, and plunge). In Papua New Guinea, Colombia, and the Congo, cloud-penetrating airborne radar was required to image the terrain. The radar data were acquired as overlapping flight strips, permitting "stereoscopic" viewing and qualitative determination of structural attitudes. Many new structures were interpreted, including anticlines and t rust faults. Unmapped lithologies were also recognized on the radar imagery by textural, tonal, and drainage pattern changes, even where there was a continuous jungle canopy. In the Congo, a topographic map to plan field operations was interpreted from the overlapping radar strips.

Landsat MSS and TM, SPOT, and Russian satellite images with new aerial photographs are being used in the Tengiz supergiant oil field of Kazakhstan to help establish an environmental baseline, generate a base map, locate wells, plan facilities, and support a geographical information system (GIS). In the Niger delta, Landsat TM and SPOT are being used to plan pipeline routes and seismic lines, and to monitor rapid shoreline changes and population growth. Accurate coastlines, facility locations, and shoreline types are being extracted from satellite images for use in oil spill models. NASA Space Shuttle radar was used during October 1994 to acquire images needed for monitoring the Indonesian rainforest within operating licenses that are perpetually covered by clouds and smoke.

Sensor characteristics, image-processing techniques, interpretation procedures, and the relationship of cost and accuracy need to be considered when implementing remote sensing. Remote sensing is greatly enhanced by integration with cartography, computer-aided drafting (CAD), Global Positioning System (GPS), DEMs, and field work. GIS that is used for overseas exploration, project management, environmental monitoring, and modeling should incorporate remote sensing.

New commercial satellites with resolutions of 1 to 4 m, a global DEM from orbital radar sensors, improved airborne hyperspectral sensors, the release of formerly classified high-resolution images, simpler GIS technology, and the extraordinary resources of Internet ensure broader application of remote sensing technology. These developments will increase the geological and environmental applications of remote sensing for the petroleum industry.

AAPG Search and Discovery Article #90953©1995-1996 AAPG Distinguished Lecturers