The evolution of sedimentary basins is largely controlled by a response in the crust to tectonically driven forces. The way in which the crust responds to those forces is controlled by the strength, composition and fabric of the crust at the time of the tectonic event. Knowing the properties of the basement of a sedimentary basin allows prediction of the behaviour of the basin during deformation.
It is the basement that responds to the tectonic stress by extending or contracting. Sedimentation patterns then respond to the resulting changes in the basement.
Potential field data (principally gravity and magnetic data) provide a window to the basement that can cover a wide continuous area. Once calibrated to geology, these data provide information that allows the development of a predictive structural model based on basement composition and structure. Depth to magnetic basement can be modelled from magnetic data and used to produca a structurally-controlled model of basement topography (e.g. SEEBASETM). Once calibrated, basement structure and topography can be used to predict basement-involved and basement-detached structures, fluid migration pathways, source distribution, reservoir and seal quality and distributions throughout the basin. The interpretation techniques and tools are efficient and cost-effective at both the country and permit or concession scale.
The methodology used to develop a comprehensive structural model relies on the integration of all appropriate geophysical and geological information. Individual datasets alone can be ambiguous and when interpreted in isolation often produce poorly constrained results. Integration is achieved by calibration of each dataset with others. Through integration, the model can be tightly constrained.
Once the datasets have been calibrated, a model consistent with all available data can be developed. Then the model can be applied and tested by re-calibrating and checking against the seismic interpretation. Adjustments can bemade as needed to both the model and the seismic interpretation at this stage.
SRK has had considerable success using a range of non-seismic tools to reconstruct basin architecture and map petroleum systems is:
- Difficult areas where volcanic/intrusive and/or salt bodies are present;
- In frontier areas where sparse 2D seismic is available;
- In mature exploration areas where adequate non-seismic data is available in addition to dense 2D and 3D datasets.
The systematic calibration, integration and interpretation of non-seismic and seismic data, working from the basement up is an efficient and effective approach in all areas. The methods are ideal for quickly developing a knowledge platform for designing cost-effective exploration and acquisition strategies in both high-risk frontier areas and more mature areas where existing concepts and dogmas may be a barrier to further exploration.
SEEBASETM is trademarked by FROGTech PTY Limited