Challenges and Pitfalls of Modelling Old and Deep Petroleum Systems: Examples from North Africa and the Middle East

Older and deeply buried petroleum systems are usually characterised by complex geological histories, and this is certainly the case for the Neoproterozoic and Palaeozoic petroleum systems of North Africa and the Middle East. In these systems, the efficiency of the source rocks and the potential to generate, migrate and trap hydrocarbons in a time frame that allows hydrocarbons to be retained are often the most critical risks. Hydrocarbons can usually only be trapped for a few tens of millions of years because even the most perfect seals are permeable over longer periods of time. One of the most critical issues determining the efficiency of older and/or deeply buried petroleum systems is, therefore, their burial history, and specifically the existence of a ‘late’ burial phase that can allow hydrocarbons to be generated, expelled, migrated and trapped in a suitably recent timeframe. Exceptions, such as the Neoproterozoic petroleum system of the Amadeus and Officer basins of Australia or the Late Neoproterozoic-Early Cambrian petroleum systems of Oman and the Indian Sub-continent generally occur where evaporite super-seals are present and/or where the post–trapping history is dominated by extreme tectonic stability.