Structural and Stratigraphic Interpretation

The establishment of a structural and stratigraphic framework is key in the exploration for oil and gas. Such an analysis requires basin analysis, sedimentological, petrophysical and geophysical workflows.

The structural framework consists of interpreted structural maps in time or depth domains to identify structural areas and what they could mean in terms of petroleum systems. For example, depocentres are usually act as hydrocarbon kitchen or potential turbidite reservoirs. On the other hand, structural highs are normally associated with very good carbonate reef reservoirs and they are the focus for hydrocarbon migration. Similarly, regional carrier bed, fault networks, salt structure and major unconformities all have a direct implication on the evolution of the petroleum system.

The sequence stratigraphic interpretation results in a series of gross depositional environment (GDE) maps which are used to identify petroleum systems elements: (1) Source rock facies: areas of accumulation and preservation of organic matter, possible lateral variations, source rock type; (2) Reservoir/carrier facies: extent of high porosity and permeability facies, anticipated regional reservoir properties, kitchen-trap connection via carrier systems ; (3) Seal facies: extent of low permeability facies. GDE maps are used in the common risk segment mapping approach to highlight areas where source, reservoir and seal are likely to be deposited. Both structural and GDE maps are the backbone of any basin and petroleum systems model.

Using the structural and stratigraphic framework, explorationists attempt to address the following questions:

• Where do source, reservoir and seal facies overlay?
• Where are the traps?

• Where and how does the geology change regionally?

• What could be a good reservoir analogue from another basin?