AAPG Bulletin; July 2006; v. 90; no. 7;
p. 1031-1058; DOI: 10.1306/02140605129
© 2006 American Association of Petroleum Geologists (AAPG)
From petroleum-type organofacies to hydrocarbon phase prediction
R. di Primio1 and
B. Horsfield2
1 Department 4 Chemistry of the Earth, Section 4.3 Organic Geochemistry, GeoForschungsZentrum Potsdam, Telegrafenberg, D-14473 Potsdam, Germany; dipri{at}gfz-potsdam.de
2 Department 4 Chemistry of the Earth, Section 4.3 Organic Geochemistry, GeoForschungsZentrum Potsdam, Telegrafenberg, D-14473 Potsdam, Germany; horsf{at}gfz-potsdam.de
Rolando di Primio joined the GeoForschungsZentrum Potsdam as a senior research scientist in 2001 after having worked as an exploration geologist in the Norwegian petroleum industry for several years. He holds a diploma in geology from the RWTH (Rheinisch-Westphälische Technische Hochschule) Aachen, Germany, and a Ph.D. from the University of Cologne. His research interests are hydrocarbon phase behavior, basin modeling, and organic geochemistry.
Brian Horsfield is a professor of organic geochemistry and hydrocarbon systems at the Technical University of Berlin, Germany, and leads the Organic Geochemistry Section at GeoForschungsZentrum Potsdam. He has 27 years of experience working with and for industry in upstream research and development. His research interests include predicting fluid compositions ahead of drilling in petroleum systems and unraveling the workings of the deep biosphere.
The organic facies concept states that kerogen abundance and composition are relatable to depositional settings. This link has been extended, using open-system pyrolysis methods, to include major petroleum types whose gross compositions are inherently defined by source rock kerogens and, hence, to petroleum composition, which directly controls the physical response of fluids to changing pressure and temperature conditions during secondary migration. The possibility to model petroleum composition during hydrocarbon generation as well as the phase behavior of the fluids during migration is now available in modern basin modeling software. However, whereas pyrolysis methods can accurately reconstruct hydrocarbon gas:oil ratios and liquid compositions, they are inherently incapable of correctly reproducing the gas composition of natural fluids, and because the gas composition dominantly controls the phase behavior of petroleums, multicompound compositional kinetic predictions based on pyrolysis results alone are inappropriate for the prediction of phase behavior. The new PhaseKinetics approach described here combines open- and closed-system pyrolysis techniques to characterize the compositional evolution of the fluids generated as a function of increasing thermal stress, as well as correcting experimentally determined gas compositions and, therefore, overcomes these deficiencies. It has been used to develop compositional kinetic schemes capable of predicting natural petroleum phase behavior for different organofacies types. The methodology uses a compositional description of the generated fluids similar to that used in pressure-volume-temperature (PVT) simulation. Selected studies in the Norwegian North Sea, Brazil, and Mexico demonstrate the quality of the tuned compositional predictions for different organic facies types.
Copyright © 2009 by American Association of Petroleum Geologists (AAPG)