Ute Mann1, Jochen Knies2
(1) SINTEF Petroleum Research, Trondheim, Norway
(2) Geological Survey of Norway (NGU), Trondheim, Norway
ABSTRACT: Depositional Environment and Source Rock Potential of Miocene Strata from the Nordic Seas, Fram Strait: Introduction of a new Computing Tool for Simulating Organic Facies Variations along 2-D Basin Transects
Organic-rich sediments were recognized in early Miocene Strata from the Norwegian-Greenland Sea (Fram Strait) during Ocean Drilling Program (ODP) Leg 151. Three organic geochemical subunits were distinguished in Hole. TOC values, HI, and d13Corg indicate a sedimentary regime dominated by type III organic matter in Subunit III (~18-16.2 Ma). Biomarker and vitrinite reflectance values point to rather fresh immature terrigenous organic matter supplied by river discharge from adjacent vegetated coastal areas. The upper two Subunits II and I (< 16.2 Ma) reveal reworked, postmature terrigenous organic matter of a distal source, possibly ice-transported and released by melting. Although the sediments of Subunit III have a moderate - good source rock potential they are insufficiently mature to generate significant amounts of oil or gas. However, assuming lateral facies variations and increased sediment thickness along the basin margins can infer better source rock quality and deeper burial of Subunit III. Further, the possible formation of an oxygen depleted zone as a result of degradation of high amounts of fresh terrigenous organic matter and higher coastal marine productivity due to enhanced nutrient supply may have caused the deposition of kerogen type II organic matter along the basin margins. The application of the OF-Mod computer software would support the idea that the poor source rock quality of Subunit III in the central Fram Strait is not necessarily representative of the entire basin system. Lateral facies changes, variations in sediment input and depositional environment were simulated in several modelling runs and resulted in a much better source rock quality along the basin margins.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado