Changes

==Prospect and location==

==Prospect and location==

Once leads have been defined, detailed analyses of individual well locations must take place. [[:file:exploring-for-structural-traps_fig20-15.png|Figure 11]] shows an example of detailed structural mapping at the prospect level. It is a structural map on top of the Upper Triassic Nugget Sandstone, Ryckman Creek field area, Uinta County, Wyoming. Contour interval varies from [[length::100 ft]] (30 m) near the crest of the structure to [[length::500 ft]] (150 m) on the flanks. The dashed contours are the oil/water and gas/oil contacts.

Once leads have been defined, detailed analyses of individual well locations must take place. [[:file:exploring-for-structural-traps_fig20-15.png|Figure 11]] shows an example of detailed structural mapping at the prospect level. It is a structural map on top of the Upper Triassic Nugget Sandstone, Ryckman Creek field area, Uinta County, Wyoming. Contour interval varies from [[length::100 ft]] (30 m) near the crest of the structure to [[length::500 ft]] (150 m) on the flanks. The dashed contours are the oil/water and gas/oil contacts.

Physical models, such as those in [[:file:exploring-for-structural-traps_fig20-16.jpg|Figure 12]], that display structures similar in shape to natural, prospect-scale, thrust-related structures can provide insight on the overall geometry of the prospect and the location of zones of high strain (high fracture density?) within the structure. These insights can be useful in determining optimal well locations.

Physical models, such as those in [[:file:exploring-for-structural-traps_fig20-16.jpg|Figure 12]], that display structures similar in shape to natural, prospect-scale, thrust-related structures can provide insight on the overall geometry of the prospect and the location of zones of high strain (high fracture density?) within the structure. These insights can be useful in determining optimal well locations.

These models were constructed of originally planar layers of limestone, sandstone, and granite. They were deformed in a pressure vessel at an effective overburden pressure of 15 × 10³ psi (1 × 10⁵ kPa). The top view is a photomicrograph of a model that simulates a thrust ramp. The bottom view simulates the hanging-wall geometry produced by movement along a series of bedding-parallel and ramp segments of a thrust fault.

These models were constructed of originally planar layers of limestone, sandstone, and granite. They were deformed in a pressure vessel at an effective overburden pressure of 15 × 10³ psi (1 × 10⁵ kPa). The top view is a photomicrograph of a model that simulates a thrust ramp. The bottom view simulates the hanging-wall geometry produced by movement along a series of bedding-parallel and ramp segments of a thrust fault.

Data on deformation mechanisms, such as fractures and how they affect reservoir properties, are obtained by integrating outcrop fracture data and laboratory estimates of fracture aperture. This integration allows for a direct calculation of fracture [[porosity]] and fracture [[permeability]] for the reservoir.

Data on deformation mechanisms, such as fractures and how they affect reservoir properties, are obtained by integrating outcrop fracture data and laboratory estimates of fracture aperture. This integration allows for a direct calculation of fracture [[porosity]] and fracture [[permeability]] for the reservoir.

Examples of outcrop fracture-spacing data relevant to the carbonate section of Whitney Canyon field are shown in [[:file:exploring-for-structural-traps_fig20-17.png|Figure 13]]. The photograph shows fractures in the Ordovician Bighorn dolomite in outcrops in the valley seen in [[:file:exploring-for-structural-traps_fig20-14.png|Figure 10]]. (Note the inch-scale measuring tape stretched across the center of Figure 20-17.)

Examples of outcrop fracture-spacing data relevant to the carbonate section of Whitney Canyon field are shown in [[:file:exploring-for-structural-traps_fig20-17.png|Figure 13]]. The photograph shows fractures in the Ordovician Bighorn dolomite in outcrops in the valley seen in [[:file:exploring-for-structural-traps_fig20-14.png|Figure 10]]. (Note the inch-scale measuring tape stretched across the center of Figure 20-17.)

The outcrop sketch in [[:file:exploring-for-structural-traps_fig20-18.png|Figure 14]] is of folds in the Devonian Darby siltstone and Ordovician Bighorn dolomite from the same location as [[:file:exploring-for-structural-traps_fig20-17.png|Figure 13]]. The numbers on the sketch represent fracture intensity values expressed as the average number of fractures encountered per foot of scanline measurement at various locations on the folds. All else being equal, higher fracture intensities should be associated with zones of higher fracture porosities and permeabilities. Maps of high fracture intensities can be used to locate optimum well locations and well trajectories in prospects.

The outcrop sketch in [[:file:exploring-for-structural-traps_fig20-18.png|Figure 14]] is of folds in the Devonian Darby siltstone and Ordovician Bighorn dolomite from the same location as [[:file:exploring-for-structural-traps_fig20-17.png|Figure 13]]. The numbers on the sketch represent fracture intensity values expressed as the average number of fractures encountered per foot of scanline measurement at various locations on the folds. All else being equal, higher fracture intensities should be associated with zones of higher fracture porosities and permeabilities. Maps of high fracture intensities can be used to locate optimum well locations and well trajectories in prospects.

==Summary==

==Summary==