payam kavousi - Profile on Academia.edu (original) (raw)
Address: Morgantown, West Virginia, United States
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A B S T R A C T Upscaling of fracture permeability in a field-size discrete fracture network (DFN... more A B S T R A C T Upscaling of fracture permeability in a field-size discrete fracture network (DFN) for a dual porosity model can be undertaken using Oda's method. It is known that Oda's method usually overestimates equivalent permeability and needs to be corrected by a flow-based numerical method. In this study we show that grid orientation can produce significant differences in single-phase (water) production volumes estimated through flow simulation in dual porosity models (Eclipse 300) when using corrected Oda's method. A five layer synthetic model in a water zone includes thirteen vertical wells. 10 ft by 10 ft structured gridding is performed in six directions: 0°, 15°, 30°, 45°, 60° and 75° counterclockwise relative to the north. The model DFN used in this study consists of three sets: a dominant, high intensity N76°W set and two lower-intensity sets that strike N28°W and N75°E similar to the fracture sets observed in the Tensleep Formation at Teapot Dome, Wyoming, USA. The single-phase (water) flow simulation using Eclipse 300 flow simulator for the six synthetic models reveals that the production varies in proportion to the geometric mean of the permeability tensor with grid rotation. The production is at its maximum when the dominant fracture set orients 45° relative to the grid cell principal directions i j (,) and falls to a minimum when the dominant fracture set is parallel to either grid wall (i or j principal directions). This research reveals a shortcoming of systematic variability of simulated production with grid orientation even though Oda's results are corrected with a flow-based numerical method.
The Tensleep oil reservoir at Teapot Dome, Wyoming, USA, is a naturally fractured tight sandstone... more 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 (CO 2 -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.
A B S T R A C T Upscaling of fracture permeability in a field-size discrete fracture network (DFN... more A B S T R A C T Upscaling of fracture permeability in a field-size discrete fracture network (DFN) for a dual porosity model can be undertaken using Oda's method. It is known that Oda's method usually overestimates equivalent permeability and needs to be corrected by a flow-based numerical method. In this study we show that grid orientation can produce significant differences in single-phase (water) production volumes estimated through flow simulation in dual porosity models (Eclipse 300) when using corrected Oda's method. A five layer synthetic model in a water zone includes thirteen vertical wells. 10 ft by 10 ft structured gridding is performed in six directions: 0°, 15°, 30°, 45°, 60° and 75° counterclockwise relative to the north. The model DFN used in this study consists of three sets: a dominant, high intensity N76°W set and two lower-intensity sets that strike N28°W and N75°E similar to the fracture sets observed in the Tensleep Formation at Teapot Dome, Wyoming, USA. The single-phase (water) flow simulation using Eclipse 300 flow simulator for the six synthetic models reveals that the production varies in proportion to the geometric mean of the permeability tensor with grid rotation. The production is at its maximum when the dominant fracture set orients 45° relative to the grid cell principal directions i j (,) and falls to a minimum when the dominant fracture set is parallel to either grid wall (i or j principal directions). This research reveals a shortcoming of systematic variability of simulated production with grid orientation even though Oda's results are corrected with a flow-based numerical method.
The Tensleep oil reservoir at Teapot Dome, Wyoming, USA, is a naturally fractured tight sandstone... more 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 (CO 2 -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.