An Integrated Approach to Geophysics and Near Surface Geology in Southern Tunisia Using GIS Techniques

By

 Simon J Robinson¹, Jock M Drummond²

(1) Anadarko International New Ventures, Uxbridge, United Kingdom (2) Anadarko Petroleum Corporation, The Woodlands, TX

 Geographic Information System (GIS) technologies provide exploration teams with excellent tools with which to combine many disparate types of data into an integrated subsurface interpretation.

We demonstrate how Anadarko has used GIS to merge the diversity of exploration data collected over the last thirty years in southern Tunisia.

In creating a large, evolving database of remote sensing, geophysical, geological, geochemical and engineering data, the database itself became the primary data management and archival tool.

GIS works as a data manipulator and spatial analysis tool, by which geographic patterns and relationships between features can be quickly ascertained from very large data sets in a wide variety of formats.

Roads, pipelines, well pads and old seismic lines identified on satellite imagery were resurveyed. Digital elevation models were used to check elevations against old survey data. Combined spatial analysis of refraction statics attributes and high-resolution aeromagnetics was used to optimally position new seismic lines. Seismic recording and positioning attributes, correlated against terrain and outcrop geology, were used to select survey parameters.

Stratigraphy and surface structure were mapped from outcrop with the assistance of geological interpretation of satellite imagery. Geologists updated their interpretation directly into the database on computers in the field.

The interactivity of GIS, the volume of data available and the spatial analysis tools facilitated far better integration of geophysics and near surface geology than was practical in the past. Such integration was paramount in the interpretation of the subtle geological structures and defining the optimal drilling locations.