Forward Modeling of Deepwater Outcrop Geobodies to Enhance Seismic Interpretation of Fluid and Lithology

Kathleen Baker* and Mike Batzle
Colorado School of Mines, Golden, Colorado

There have been many studies of how Direct Hydrocarbon Indicators (DHIs) can help (or hurt) us when trying to distinguish fluid effects on seismic amplitudes. DHI’s have proven to be useful in identification of pore fluid types, but geologic complexities can impact the seismic signature in a way that may lead to misidentification of fluid indicators. Deep-water turbidite sequences have inter-fingered boundaries such as channel complexes, gradational contacts due to stratigraphic pinch outs, and abrupt changes in properties at scales well below seismic resolution. A better understanding of the lithologies and geometries that control fluid distribution can be achieved by using analog outcrop observations to enhance the interpretation of subsurface information such as well logs, seismic data and regional geologic models. Here we present a case study of the Ursa field in the deep-water GOM and show how the integration of outcrop studies can enhance the interpretation of complex reservoirs in deep-water depositional settings. A methodology of the investigation is presented starting with linking the outcrop depositional system to the GOM depositional system, calibration and detailed analysis of GOM well log, rock and fluid properties to seismic data. Forward and inverse modeling, and analysis of the DHI response. Also, examples of outcrops and 1-D and 2-D models are presented. The results show that these deep-water outcrop analog help better predict frequency and occurrence of turbidite sequences when combined with well log and seismic and DHI’s. One key insight is the lithofacies impact on seismic data may be an alternative explanation for the occurrence of high amplitude seismic events, which may be misidentified as commercial hydrocarbon indicators.

AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands

AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands