Flow Cell Experiments of Organic Compounds in Clastic Reservoir Rocks

Angela Meier¹, Reinhard Gaupp¹, Bernhard M. Krooss², and Ralf Littke^2
1Institute of Earth Sciences, Friedrich-Schiller-University, Jena, Germany
²Chair of Geology and Geochemistry of Petroleum and Coal, RWTH Aachen University, Aachen, Germany

Within the scope of this DFG-funded project, we investigate the interaction of petroleum compounds with hematite grain-coatings on mineral surfaces and their effects on porosity, permeability, and pore structure of clastic reservoir rocks. We want to evaluate the hypothesis that liquid hydrocarbons in hematitic reservoirs can generate reactive organic acids and/or carbon dioxide during post-emplacement thermal evolution. The expected outcome could allow a better understanding of mechanisms of reductive bleaching and porosity enhancement in red sandstones by the presence of liquid hydrocarbons.

Flow cell experiments were designed with red bed sandstones from the Upper Rotliegend from the North German Basin under elevated temperature and pressure conditions and different reactant fluids. The sandstone samples and fluids are characterized prior and after experiments. Preliminary short-term experiments started with deionized water. Mineral reactions are monitored by analysis of the ionic species in the post experimental fluids by ICP-MS/-OES and titration methods. They showed a significant concentration of silicon, calcium, potassium, aluminum, and carbonate species. Comparative petrographic-mineralogic investigations of the sandstone samples indicate leaching of carbonate cements and detrial feldspar grains. Further short- and long-term experiments were accomplished with organic fluids consisting of a mixture of n-alkanes. Long-term experiments are carried out with complex organic fluids and petroleum in interaction with the inorganic framework of water saturated sandstone samples. In the advanced stage of the investigations we will have a focus on the change of the mineral surfaces caused by reactions with reactants in different resolutions by VSI (in cooperation with the scientific working group of Prof. A. Lüttge, Rice University Houston/Texas), SEM, AFM, and TEM.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas