ABSTRACT

Mixed age Mesozoic and Cenozoic hydrocarbons in many Louisiana oil and gas reservoirs result from the dynamic process of upward vertical migration of hydrocarbons from deeper, older source rocks and/or reservoirs. Increasing levels of thermal maturation are achieved from the passage of such source/reservoir zones as basin sedimentary loading progresses. The entire process of generation migration mixing may be repeated through several cycles. This generally results in a vertical progression of younger and younger reservoirs holding some thermally up graded admixtures of older, and sometimes even more mature, hydrocarbons than those capable of being derived from nearby lateral or subjacent source beds.

Integrated spatial temporal mapping is helpful in predicting the probable location of the following: (1) hydrocarbon generating paleo geothermal conditions, (2) paleo geopressure zones, and (3) zones of tectonism. Such maps and cross sections assist in identifying former or present potential hydrocarbon source zones, the location of probable microfracturing that may have assisted in the initial expulsion and migration processes, and major regional vertical migration conduits.

Simulation of the generation migration mixing process is illustrated for specific Louisiana Cretaceous and Tertiary reservoirs.

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