Development of predictive models for the distribution of hydrocarbon reservoir rocks in rift basins
Major oil companies around the world are using models developed by our researchers to find new reserves of oil and gas. Following discovery of new fields, our models also help companies to position their wells optimally, reducing the number of $50-100 million wells they have to drill to exploit a reservoir fully.
Oil companies are always on the lookout for new sources of oil and gas. Although they know that over 200 billion barrels of recoverable hydrocarbons lie in rift basins, they have struggled to find a reliable and consistent method for locating these hidden reserves.
VRGS has been licensed to Chevron, ConocoPhillips and Fugro Robertson and others involved in oil exploration.
Working in collaboration with oil companies, researchers from the Department of Earth and Environmental Sciences developed conceptual models that predict the relationship between movement on rift faults, the distribution of reservoir sandstones and limestones and the movement of fluids within these rocks. The models have been tested and refined through geological fieldwork in rift basins such as the Gulf of Suez and guide the interpretation of seismic reflection data to predict the location and physical characteristics of hydrocarbon rocks within these previously hard-to-analyse basins.
The research team also developed new software – the Virtual Reality Geological Studio (VRGS) – which uses scans of rock outcrops to produce new data on their structure and sediment composition. The new data are used to generate realistic models and visualisations of hydrocarbon reservoirs, removing some of the uncertainty around conventional surveying and characterisation techniques.
An oil well costs between $50 and $100 million to build.
The techniques and tools developed through our research help oil companies to pick the best locations for their new oil wells. As each well costs $50-100 million to build, the savings are substantial.
The information from our systems can also highlight the location of reservoirs near to existing wells that oil companies can easily tap into without having to invest in much new infrastructure.
Leading international and national oil companies on all continents have embedded these new models into their exploration activities worldwide, such as the South Atlantic conjugate margin, where new substantial reservoirs have been found in unusual areas such as French Guyana and Ghana.
Study show that there are 200 billion barrels of recoverable oils in the South Atlantic basin.
For the first time, the researchers applied concepts from structural geology to stratigraphic analysis of rift basin rock successions. They developed a deeper understanding of how stratal geometries and reservoir rocks are distributed within rift basins, leading to developments in process-response models for sedimentation in rift basins.
- Sequence stratigraphy – extending simple 2D data processing into a rigorous 3D analysis;
- Discovery that relay zones are important in the delivery of sediment to rifts at fault tips;
- Discovery that the depositional dip at the end of a relay zone can be multi-directional;
- Combination of 3D patterns of subsidence uplift with data on sea level changes and theories of sediment supply to produce holistic tectono-sequence stratigraphic models for rift basins;
- Extension of the concepts to include carbonate reservoirs in rift settings;
- Understanding the role of rift faults and sequence stratigraphy in the movement of dolomitizing fluids and the enhancement of porosity in carbonate reservoirs;
- Development of ‘digital outcrop’ techniques to collect quantitative data for modelling, including the Virtual Reality Geological Studio (VRGS) software, now licensed to oil companies and universities;
- Extension of the concepts to extensional basins of all ages around the world.
The rift basin studies were initiated in the late 1980s by Professor Rob Gawthorpe and several generations of PhD students and have become embedded in the work of the Basins and petroleum Geoscience Group. Studies have continued in North Africa (Prof Jonathan Redfern) and have been extended to carbonates by Dr Cathy Hollis. More recent members of the group are widening the scope of the work to mudrock studies (Prof Kevin Taylor) and to deepwater settings (Prof Stephen Flint).