All the positive elements for the formation and accumulation of hydrocarbons (oil and gas) in commercial quantities exist in the Trinidad area, i.e. traps, reservoir rocks and source rocks.
Trinidad is situated at the triple junction formed by the meeting of three plates, the Caribbean, South American and North Atlantic Plates. As a result, this small island and its surroundings is one of the most geologically complex areas of the world and has often been called “the graveyard of geologists” by commentators on our geological history. However, we continue to attract international oil exploration companies who, although challenged by this complexity, are always convinced that their theories are better than their competitors’ and that they would be successful in discovering new accumulations of petroleum. The interaction of these plates at the triple junction, with each other and the plates surrounding them has resulted in the formation of folded (anticlines) and faulted structures, ideal structural traps for the accumulation of petroleum. To date, most wells have been drilled to structural traps or combination structural/ Stratigraphic traps.
The high porosity and permeability of sedimentary rocks, which are required characteristics of all good reservoir rocks, influence their ability to store and produce fluids. In Trinidad all the reservoirs are Sandstones. In other parts of the world, e.g. Mexico and the Middle East, some of the major reservoirs are limestone.
The source rock from which most of the oil is generated is the Cretaceous age Naparima Hill Formation. The rocks of this formation outcrop at three locations in Trinidad, but the most accessible location is the San Fernando Hill which can be seen from any of the entrances into San Fernando. Students who visit the San Fernando Hill should look for evidence of oil in the fractured surfaces of broken pieces of rock. Most of the time the oil appears as a black, tarry substance.