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.