Abstract

The Tensleep oil reservoir at Teapot Dome, Wyoming, USA, is a naturally fractured tight sandstone reservoir that has been considered for carbon dioxide enhanced oil recovery (CO2-EOR) and sequestration. Interpretation of open fractures identified in wireline image logs from the field suggests that the reservoir fracture network is dominated by early formed structural hinge-oblique fractures with interconnectivity enhanced by hinge-parallel and hinge-perpendicular fracture sets. Previous studies show that 3D seismic scale discontinuity attributes are dominated by more recent hinge-parallel and strike slip trends. The most negative curvature attribute that we used highlights concave features attributed to subtle traveltime delay through fracture zones and small faults or flexures associated with the fracture swarms. The poststack discontinuity extraction workflow incorporated seismic spectral blueing (SSB) to enhance the resolution of the seismic data. The SSB process is followed by computation of the short-wavelength most negative curvature. Subsequently, the minimum similarity attribute is applied to accentuate regions with minimum similarity of curvature. An edge-illumination process is then applied to the minimum similarity of the most negative curvature output. Discontinuities extracted through edge illumination locate regions of minimal similarity in curvature along fracture zones or small fault boundaries. This workflow enhances hinge-oblique discontinuities without azimuthal filtering and provides a fracture intensity attribute, which is used as an input to distribute the fracture intensity through the model discrete fracture network. Qualitative correlation of production data to extracted discontinuities suggests that wells located on hinge-oblique discontinuities are more productive than other wells in the field.

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