Three-dimensional geological models from outcrop data using digital data collection techniques: An example from the Tanqua Karoo depocentre, South Africa

David Hodgetts*, N. J. Drinkwater, J. Hodgson, J. Kavanagh, S. S. Flint, K. J. Keogh, J. A. Howell

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

71 Citations (Scopus)


Recent technological advances have made the collection of digital geological data from outcrops a realistic and efficient proposition. The world-class exposures of Permian basin-floor turbidite fans of the Tanqua depocentre, Karoo Basin, South Africa have been the focus of one such study. These outcrops are faulted at a subseismic scale (displacements of up to 40 m), with continuous exposures of up to 40 km in depositional dip and 20 km strike directions. Digital data collection has been undertaken using a variety of methods: differential global-positioning systems (DGPS) mapping, surveying using laser total station and laser rangefinders, ground- and helicopter-based digital photography and photogrammetry, and digital sedimentary outcrop logging as well as geophysical data from boreholes. These data have then been integrated into several 3-D geological models of the study area, built using a subsurface reservoir-modelling system. The integrated dataset provides insights into the stratigraphic evolution of a deep-water fan complex by allowing true 3-D analysis and interpretation of data collected in the field. The improved understanding of these deep-water fan systems will improve existing models of offshore analogues by enhancing understanding of geometries and trends not resolvable from existing offshore data and by identifying potential problematic areas for fluid flow. Initial results from the application of this approach have been successfully applied to the conditioning of stochastic geological models of a subsurface deep-water reservoir from the North Sea.

Original languageEnglish
Pages (from-to)57-75
Number of pages19
JournalGeological Society Special Publication
Publication statusPublished - 2004

Bibliographical note

This work was carried out as part of the consortium research project, NOMAD, which is sponsored by the European Union's 5th Framework Programme under the Energy, Environment and Sustainable Develop- ment thematic programme. The NOMAD consortium is an international, joint industry/university venture comprising: Schlumberger Cambridge Research (UK); Statoil (Norway); Liver- pool University's Stratigraphy Group (UK); Stellen- bosch University (South Africa); and the Technical University of Delft (Netherlands). The NOMAD objective is to help optimize the positioning, number and deliverability of production wells drilled in deep-water reservoirs, thus improving hydrocarbon recovery while reducing development costs. This will be achieved through improved reservoir characterization, using a 3-D geological and petrophysical model of the world's best outcrop analogue of deep-water sediments for guidance: the Permian Tanqua Basin turbidite fan complex in South Africa. Many of the results presented in this paper are from the collected efforts of a large number of field geologists from the NOMAD partner institutions. The authors would like to thank them collectively. (See: for further details.)


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