PETROLEUM SYSTEMS - MODELS AND APPLICATIONS

The term "petroleum system" - barely twenty years old - incorporates a new view of the formation of hydrocarbon accumulations. The concept is based on an orderly sequence of geological phenomena, starting with the genesis of oil or gas, which then migrates and is finally trapped. This sequence of events depends closely on the geodynamics of the sedimentary basin, which is determined by global plate-tectonics. The main petroleum system models can therefore be defined in terms of the major types of basin. There are three main systems - continental rift, platform, and orogenic - each of which has a number of variants: continental rifts provide good conditions for oil generation, vertical migration and accumulation at various levels; by contrast, platform systems encourage the formation of reservoirs at the expense of source rocks and long, lateral migration paths, which frequently form tar- belts; and orogenic systems encourage entrapment in zones little affected by tectonic movements, accompanied by frequent surface shows. The "petroleum system" concept describes the dynamic, mobile formation of petroleum pools, and has a number of implications for exploration strategy.