To examine the state of hydrocarbons and water in the
Wind River Basin of Wyoming, the following data types
are compiled and presented at the basin scale: fluid type,
pressure, and temperature from drillstem tests; watersalinity
and cumulative hydrocarbon production from oil and gas
wells; vitrinite reflectance data; and sonic well logs. The
spatial distribution of produced fluids shows the nearly
ubiquitous presence of mobile water, even in highly productive
gas-charged formations. Sonic logs record a basin wide
velocity decrease in the Lower Cretaceous Thermopolis Shale
through the Upper Cretaceous Cody Shale that is attributed
to a combination of paleo-overpressuring and present-day
overpressuring. Pressure-elevation plots and mud weights
reveal the presence of two large pressure compartments in
the Madden area, one above the Waltman Shale Member of
the Paleocene Fort Union Formation and the other below it.
Temperature data reveal hot and cold spots around structures
in the marginal parts of the basin where the Waltman Shale
Member of the Fort Union Formation is absent. The highest
temperature gradients are in the upper pressure compartment
in the Madden area. Vitrinite reflectance data record little
change with increasing depth throughout much of the geologic
section in shallow parts of the basin and a steady increase
of log (Ro
) with depth in the deep parts of the basin. The
varied distribution of fluids, pressure, and temperature reflect
the complex history of subsidence, thrusting, hydrocarbon
generation, water migration, and uplift in and marginal to this
large, asymmetric intermontane basin.
