--> The Diagenetic Effects of Hydrocarbon Saturation in Sandstones, by D. R. Britton and R. C. Surdam; #90986 (1994).

Datapages, Inc.Print this page

Abstract: The Diagenetic Effects of Hydrocarbon Saturation in Sandstones

Douglas R. Britton, Ronald C. Surdam

The effects of liquid hydrocarbon saturation on sandstone diagenesis were studied by a petrologic comparison of surface and subsurface hydrocarbon saturated and unsaturated lacustrine sandstones of the Green River Formation. Further, approximately five grams of clean ferric-rich Green River Formation sandstones were heated with 10 grams of water and 10 grams of liquid hydrocarbon for 72 hours at 100°C simulating potential reservoir conditions.

Surface and subsurface ferric-rich unsaturated sandstones contain an average 7% and 1% porosity, respectively, with porosity primarily occluded by carbonate cements and clays. The corresponding ferrous-rich hydrocarbon saturated sandstones contain an average 24% and 8%, respectively, with remnant calcite cements and clays. These observations suggest that significant organic/inorganic reactions occur between oxidized iron phases and liquid hydrocarbons, significantly enhancing porosity by dissolving the carbonate cements.

Experimental results suggest a mechanism for porosity enhancement generated by organic/inorganic reactions. Redox reactions occur between the liquid hydrocarbons and the ferric-rich iron phase, including oxidation of the hydrocarbon to organic acids and carbon dioxide, and reduction of the oxidized iron.

It is concluded that significant porosity enhancement in the Green River Formation sandstones may be attributed to redox reactions, organic/inorganic reactions between liquid hydrocarbons and ferric-rich iron minerals. The result of these reactions is the oxidation of the hydrocarbon to organic acids and/or carbon dioxide, and the corresponding reduction of the ferric iron minerals to ferrous iron phase, and porosity enhancement due to carbonate dissolution.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994