Changes

==Tectonic setting==

==Tectonic setting==

The figure below depicts the tectonic setting for the western U.S. relevant to Laramide plate tectonics. It shows where overthrusting took place, its overall geometry and ver-gence direction, and the interference with foreland deformation.

[[file:exploring-for-structural-traps_fig20-5.png|thumb|{{figure number|1}}. Copyright: Schwartz, 1982; courtesy Rocky Mountain Assoc. of Geologists.]]

[[file:exploring-for-structural-traps_fig20-5.png|thumb|{{figure number|20-5}}. Copyright: Schwartz, 1982; courtesy Rocky Mountain Assoc. of Geologists.]]

[[:file:exploring-for-structural-traps_fig20-5.png|Figure 1]] depicts the tectonic setting for the western U.S. relevant to Laramide plate tectonics. It shows where overthrusting took place, its overall geometry and ver-gence direction, and the interference with foreland deformation.

 

[[file:exploring-for-structural-traps_fig20-6.jpg|thumb|{{figure number|2}}See text for explanation.]]

==Structural domains==

==Structural domains==

Structural domains within the Wyoming thrust belt were defined by the regional mapping of the U.S. Geological Survey<ref name=ch20r232>Rubey, W., W., 1973, Geologic map of the Afton quadrangle and part of the big Piney quadrangle, Lincoln and Sublette counties, Wyoming: U., S. Geological Survey map I–686.</ref> and by interpreting satellite images such as the one shown in the figure below. Individual major thrust sheets were defined across the belt as well as their change in character along strike, thus defining domains on a large scale. Note that the small white rectangle in the center of the satellite image is the approximate area seen in the oblique aerial photograph in Figure 20-12.

Structural domains within the Wyoming thrust belt were defined by the regional mapping of the U.S. Geological Survey<ref name=ch20r232>Rubey, W., W., 1973, Geologic map of the Afton quadrangle and part of the big Piney quadrangle, Lincoln and Sublette counties, Wyoming: U., S. Geological Survey map I–686.</ref> and by interpreting satellite images such as the one shown in [[:file:exploring-for-structural-traps_fig20-6.jpg|Figure 2]]. Individual major thrust sheets were defined across the belt as well as their change in character along strike, thus defining domains on a large scale. Note that the small white rectangle in the center of the satellite image is the approximate area seen in the oblique aerial photograph in [[Figure 20-12]].

[[file:exploring-for-structural-traps_fig20-6.jpg|thumb|{{figure number|20-6}}See text for explanation.]]

==Prospective structural fairways==

==Prospective structural fairways==

[[file:exploring-for-structural-traps_fig20-7.png|thumb|{{figure number|3}}.]]

Within the structural domains, regional analysis of structural style and timing were integrated with other elements of the hydrocarbon system to define prospective fairways. The figure below covers approximately the same area as the preceding satellite image and shows the location of the major thrust sheets in the Wyoming thrust belt. Note that most of the oil and gas fields occur in the southern half of the Absaroka thrust sheet.

[[file:exploring-for-structural-traps_fig20-7.png|thumb|{{figure number|20-7}}.]]

[[file:exploring-for-structural-traps_fig20-8.png|thumb|{{figure number|20-8}}.]]

The figure below is a contoured fault-plane map at two different scales for the Absaroka thrust, the major thrust that contains the producing fairway.

Within the structural domains, regional analysis of structural style and timing were integrated with other elements of the hydrocarbon system to define prospective fairways. [[:file:exploring-for-structural-traps_fig20-7.png|Figure 3]] covers approximately the same area as the preceding satellite image and shows the location of the major thrust sheets in the Wyoming thrust belt. Note that most of the oil and gas fields occur in the southern half of the Absaroka thrust sheet.

[[file:exploring-for-structural-traps_fig20-8.png|thumb|{{figure number|20-8}}.]]

[[:file:exploring-for-structural-traps_fig20-8.png|Figure 4]] is a contoured fault-plane map at two different scales for the Absaroka thrust, the major thrust that contains the producing fairway.

==Structural lead==

==Structural lead==

Figure 20-11 on the opposite page shows a cross section across the Whitney Canyon and Ryckman Creek producing structures in the upper plate of the Absaroka thrust.

[[file:exploring-for-structural-traps_fig20-9.png|thumb|{{figure number|5}}See text for explanation.]]

 

Detailed analysis of the fairway proceeded using surface and subsurface data. Examples of the data used are shown [[below and on the next few pages]].

The figure below shows an interpreted seismic line in the approximate location of Figure 20-11.

[[:file:exploring-for-structural-traps_fig20-11.png|Figure 7]] shows a cross section across the Whitney Canyon and Ryckman Creek producing structures in the upper plate of the Absaroka thrust.

[[file:exploring-for-structural-traps_fig20-9.png|thumb|{{figure number|20-9}}See text for explanation.]]

[[:file:exploring-for-structural-traps_fig20-9.png|Figure 5]] shows an interpreted seismic line in the approximate location of [[:file:exploring-for-structural-traps_fig20-11.png|Figure 7]].

The figure below shows restoration and balancing of a cross section through the Whitney Canyon and Ryckman Creek fields. Restoration and balancing help ensure that structures shown on cross sections are geometrically possible and geologically plausible.

[[file:exploring-for-structural-traps_fig20-10.png|thumb|{{figure number|6}}.]]

[[file:exploring-for-structural-traps_fig20-10.png|thumb|{{figure number|20-10}}.]]

[[:file:exploring-for-structural-traps_fig20-10.png|Figure 6]] shows restoration and balancing of a cross section through the Whitney Canyon and Ryckman Creek fields. Restoration and balancing help ensure that structures shown on cross sections are geometrically possible and geologically plausible.

[[file:exploring-for-structural-traps_fig20-11.png|thumb|{{figure number|20-11}}. Copyright: Lamerson, 1982; courtesy Rocky Mountain Assoc. of Geologists.]]

[[file:exploring-for-structural-traps_fig20-11.png|thumb|{{figure number|7}}. Copyright: Lamerson, 1982; courtesy Rocky Mountain Assoc. of Geologists.]]

The oblique aerial photograph below shows structures in the upper plate of the Absaroka thrust in the central Wyoming thrust belt, updip and along strike of the producing structures in the same thrust sheet to the south. (See Figure 20-6 for the location.)

The oblique aerial photograph below shows structures in the upper plate of the Absaroka thrust in the central Wyoming thrust belt, updip and along strike of the producing structures in the same thrust sheet to the south. (See Figure 20-6 for the location.)