ABSTRACT

Our Gulf Coast Region is, in a sense, magical. It is widely thought to hold the most important oil and gas reserves of the U.S. lower 48, found and unfound. This northern limb of a continuously evolving petroliferous basin may be the finest place in the world to observe and confirm the workings of an active oil and gas-making system. Not only is it remarkably accessible, but the quantity and variety of information available are probably unmatched anywhere.

This paper describes a few simple but vital principles that may help to explain the Gulf Coast magic. No attempt is made to summarize the burgeoning Gulf Coast literature, and only a few references are made to specific field data. Cartoons and diagrams are used to visualize ideas. Those who know the Gulf Coast are qualified to judge the validity of the reasonsing.

Attention centers on interactive sediment-fluid relationships characteristic of shelf and hingeline situations. The relevance of differential compaction, subsidence, growth-faulting, diapirism, and abnormal pressures to focussed water movement is examined. The hydrologic interplay of offshore compaction effluent and onshore meteoric recharge is shown to enhance the entrapment of water-borne materials (especially hydrocarbons) in the coastal belt. Probably the same magic can be projected backward (and forward) in the geologic history of the Gulf Coast province, explaining many of the inland productive trends paralleling the present coastal belt.

The northern Gulf Coast Geosyncline is a remarkably efficient oil and gas-making apparatus. It continues active today, allowing direct observation of what is going on. Some observations seem to be at odds with traditional concepts of petroleum origin. The same observations, however, help to explain the extreme diversity in size and quality of trapped hydrocarbon mixtures known in the Gulf today.