Abstract

The petroleum system concept is used to investigate discovered hydrocarbon accumulations and provide a basis for proposing complementary plays and prospects, the undiscovered commercial accumulations. Characterization of a petroleum system includes the procedure to identify, map, and name the hydrocarbon fluid system and to summarize the results on a folio sheet. Plays and prospects described in the context of a petroleum system are complementary plays and prospects.

The petroleum system folio sheet includes four figures, a table, and text that best depict the geographic, stratigraphic, and temporal evolution of the system. The figures and table include (1) a burial history chart to establish the critical moment for the system, (2) a map and (3) a cross section, both drawn at the critical moment to depict the hydrocarbon fluid system, (4) an events chart to summarize the formation and history of the petroleum system, and (5) a table of genetically related accumulations. The trap-forming and generation-migration-accumulation processes and their temporal relationship to one another on the events chart provides the link between the complementary play/prospect and the petroleum system.

Three independent variables comprise the link between the petroleum system and the complementary play/prospect: trap, petroleum charge, and timing. They are independent because each can occur without the other, and they represent three separate entities; rock, fluid, and time, respectively. The events chart shows the temporal link between the independent variables, whereas the map and cross section show the spatial relationship. The relative ease with which this three-component link is made is a measure of exploration risk.