Oil and Gas
Oil and Gas | Clastics
This field class examines the links between depositional processes, facies distribution, reservoir architecture and stratigraphic evolution of the deepwater complexes of the southwestern Karoo Basin, South Africa. The differences in morphology, stacking patterns and stratigraphic fills of channels from basin floor to shelf margin/fluvial systems are investigated. The course reviews the evolution down fan from net-bypass to net-deposition, confined/unconfined transport and deposition and the development and distribution of depositional elements (channel, lobes and levee/overbank deposits).
Duration and Training Method
A six-day field course visiting the Tanqua and Laingsburg subabsins of the Karoo. The proportion of field time to classroom time is approximately 90:10. Field exercises include interpretation of cliff exposures on photo panels and measuring of vertical sections and are aimed at developing a sense for scale, i.e. from seismic to core and log scale, and an understanding of vertical stacking patterns and architectural style of depositional elements. Participants are also encouraged to bring some of their own data for further discussion.
Participants will learn to:
- Appraise the depositional processes and products of fine-grained, basin floor to slope turbidite systems at various scales.
- Predict the development and distribution of facies and facies associations of deepwater fan systems in slope through basin floor settings.
- Evaluate the architectural styles of different channel types, channel complexes and complex sets in basin floor, base-of-slope and lower slope settings, as well as their association with frontal splay and levee/overbank deposition.
- Evaluate the significance of linked debrite deposits in the palaeogeographic reconstruction of deepwater deposits.
- Compose depositional models illustrating reservoir architecture and quality in highly confined to unconfined depositional settings and predict flow barriers related to different orders of depositional cyclicity.
- Predict the vertical and lateral stacking patterns and internal architecture of sheet sandstones as related to relict depositional topography and volume of flows.
- Evaluate the significance of fan pinch-out lithologies in terms of reservoir potential and sealing aspects.
- Assess mechanisms of fan evolution in terms of high-frequency sandy growth phases, periods of starvation and its bearing on the distribution of reservoir and non-reservoir facies.
- Evaluate the influences of basin floor and slope topography on facies distribution.
- Integrate different scales of observation including basin/exploration scale (sequence expression on the basin floor and sequence stacking) and development/ production scale (facies distribution, stacking patterns, bed-scale stratigraphy and hierarchy of architectural elements) within distributive deepwater systems.
The excursion will visit areas of world class 3D exposures where minimal vegetation and variable outcrop orientation enable virtually all areas of a fan system and the architecture of stacked fans to be examined in a 3D sense.
A central theme of the course will be to explore the link between depositional processes, sequence stratigraphic framework, facies distribution, and resultant architecture in a generic sense. As such, the ideas presented are exportable worldwide.
The key points to be addressed in studying the western Karoo deepwater deposits include:
- Comparison of unconfined versus confined fan deposition.
- Sequence stratigraphic concepts in deepwater systems including relative base-level controls on sediment supply to the basin, depositional signature of superimposed high-frequency and low-frequency cyclicity, and prediction of flow barriers related to different orders of depositional cyclicity.
- Channel types and their evolution down-fan from erosional/bypass to erosional/depositional to depositional to pinch-out channels at the far basinward limit. Differences between channels in basin floor, base of slope and lower slope settings. Channel-fill/overbank relationships.
- Sheet sandstones and differentiation between distal (down-fan) and lateral (overbank/interchannel) types.
- Stratigraphic significance in fan pinch-out areas in terms of facies characteristics, reservoir potential and sealing issues.
- Mechanisms of fan growth in terms of high-frequency sandy growth phases, separated by fan-wide starvation zones (‘flooding surfaces’).
- Development of a model for lithology and reservoir quality prediction in fans deposited on a simple basin floor.
- The opportunity to see the stratigraphic fill for the Tanqua subbasin from the deepwater fans, through the slope and shelf margin to shallow marine and fluvial systems. The deepwater elements form the focus of the course itinerary.
Arrival in Cape Town.
Breakfast meeting including course and driver safety briefing.
Travel from Cape Town to Inverdoorn Game Reserve. Drive through Cape Fold Belt region via scenic Bains Kloof Pass.
Course introductory talk before dinner.
Overnight - Inverdoorn
Stop 1: Ongeluks River channel complex, base of slope setting, most proximal outcrops of Fan 3. Prediction of facies down-dip and marginally away from the channel complex. Team exercise on photo panels prior to investigating the outcrops.
Stop 2: Fan 5. Pienaarsfontein SE Berg. Ripple cross-laminated fan margin/overbank type facies lateral to Klein Hanklip channel complexes, lower slope setting.
Stop 3: Fan 5. Kleine Hanklip. Lower slope channel complexes and interchannel slope deposition. Architectural style of laterally and vertically stacked channel-fills exposed in dip and strike sections. Team exercise on photo panel interpretation to focus on channel architecture and stacking patterns.
Stop 4: Kleine Rietfontein. Large-scale architectural styles of Fans 1, 2 and 3, channel fills within Fan 4, thin-bedded overbank facies, associated crevasse channel fills. Comparison of Fan 3 facies assemblage with Ongeluks River section. Prediction of facies towards the fan axis of Fan 3.
Stop 5: Kanaalkop channel-fill. Channel-fill/overbank relationship in Fan 3. Internal facies and reservoir characteristics of Fan 2.
Stop 6: Los Kop. Pinch out characteristics of Fan 2, broad “channel-fills” near fan axis of Fan 3. Architectural styles of axial “channel-fills” and their lateral changes from axis to off-axis. Team exercise on photo panels.
Stops 7-9: Fan 3 eastern margin and Fan 4. Sedimentary characteristics and internal architecture of sheet-like lobes, interfan sections, reservoir implications.
Stop 10: Klipfontein area. Group climbs through Fans 3, 4 and 5 and throught the slope succession above Fan 5 (optional) i.e. experiencing a complete exposure from basin floor to shoreface.
Examine depostional characteristics and architectural style of Fan 3 (distal pinch-out area), Fan 4 (mid-outer fan sheets and transitional elements) and Fan 5 (base of slope, high aspect ratio channelised). Transition to shelf/prodelta/delta front deposits overlying Fan 5.
Depart Inverdoorn, drive to Laingsburg.
Overview stop outside Laingsburg town for stratigraphy of the Ecca Group in the Laingsburg subbasin.
Stop 1: Grootkloof area. High resolution basin floor fan stratigraphy (Fan A).
Stop 2: Skeiding, Fan B, stacked base-of-slope channel fill deposits. Lateral facies variation from stacked channel-fill to off-axis levee-overbank.
Stop 3: Paardefontein, Fan B architecture - 10 km down-dip from Skeiding.
Stop 4: Architecture of erosive slope setting channel fills along C/D ridge.
Stop 5: Paardefontein, Fan B architecture - 15 km down-dip from Skeiding.
Stop 6: Jakkalsfontein. Stratigraphy of Fan A and Fan B - controlled by early anticlinal basin floor topography? Fan B - medium to thin-bedded ripple-laminated succession.
Stop 7: Waterkloof. Thin-bedded fan margin deposits of Fan B - result of basin floor control on facies distribution?
Depart from Matjiesfontein. Travel N1 via Hex River Valley and Worcester to Cape Town.
Who Should Attend and Prerequisites
Geoscientists actively involved in exploration and development in deepwater clastic systems. This class will appeal to those working in a range of disciplines including geologists, geophysicists, quantitative seismic interpreters and reservoir engineers.
De Ville Wickens
Following the completion of his BSc Honours degree in Geology at the University of Stellenbosch, De Ville started his career with the Geological Survey of South Africa (now Council for Geoscience) in 1976 as a field geologist, primarily responsible for regional mapping. After 12 years with the Geological Survey, during which time he also received his MSc degree from the University of Port Elizabeth, he took up a newly created post as specialist sedimentologist with the state petroleum exploration company, SOEKOR (now PetroSA), in 1987. As specialist, his work involved close cooperation with all disciplines related to the exploration for oil and gas in the offshore along the West and South coast of South Africa. The discovery of oil in turbidite reservoirs in offshore Bredasdorp Basin led to an extensive land-based research program on the deep-water fan complexes of the southwestern Karoo Basin, initially in collaboration with Arnold Bouma of Louisiana State University and later with the Strat Group of the University of Liverpool. De Ville’s interest in the deltaic and deep-water systems of the Permian Karoo Basin led to a PhD via the University of Port Elizabeth in 1994. He left SOEKOR in 1996 where after he continued to serve the national and international petroleum industry as consultant, mainly via field research and training in the form of field seminars. After 3 years of consultancy for all the major oil and gas companies of the world, he joined the Department of Geology at the University of Stellenbosch as a senior lecturer in sedimentary geology, a position initiated and supported by the local petroleum industry. Apart from a full under- and post-graduate programme, he continued leading and co-leading numerous field seminars in which more than a thousand geoscientists have been involved up to now. De Ville took early retirement from Stellenbosch at the end of 2007 to focus on and to broaden his consultation business.
De Ville’s training has been in sedimentary geology with specialization in deep-water deposits. He is a highly experienced field geologist with a strong background in petroleum exploration, teaching and academic research.
Affiliations and Accreditation
PhD University of Port Elizabeth
MSc University of Port Elizabeth
BSc University of Stellenbosch - Geology, Honours
AAPG - Active Member
Geological Society of South Africa - Member
N107: Turbidite Facies Architecture, Reservoir Applications and Predictive Stratigraphy (Karoo, South Africa)