Greater Green River Basin

[4] The Rock Springs Uplift is a 1,200 square mile asymmetric anticline composed of Late Cretaceous Baxter Shale.

The Baxter Shale is extremely eroded forming a deep depression surrounded by sandstone escarpments that are part of the Mesaverde Group.

Above the Mesaverde Group escarpments are incised valleys that contain the Lewis Shale, Fox Hills Sandstone, and the Lance Formation.

It is defined by multiple outcrops the most prominent being Oyster Ridge, a North to South angled hogback that exposes the Cretaceous Frontier Formation sandstone.

It is a desert plains environment separated from the Green River Basin by the Rock Springs Uplift to the West.

[1] The clastic alluvium units now serve as a great reservoir rock for the marine shales deposited from the Permian into the Cretaceous.

It is thought that the oil from these shales have migrated into the Pennsylvanian Tensleep Formation, and Paleozoic reservoirs of Central and Eastern Wyoming.

Due to its carbonate and chert rich depositional environment, the oil found in the Phosphoria Formation as a high sulfur content making it Type-IIS kerogen.

[6] The Tensleep Formation is the most prominent reservoir rock hosting approximately 142 million barrels of oil with about 12 fields producing from this unit.

[7] The Mowry Shale is a well-known source rock of Paleozoic reservoirs in Wyoming with the highest total organic content in the area.

[5] It is known to source the Dakota Sandstone and Frontier Formation both prolific reservoirs in the Rocky Mountain Region.

[7] The Mowry Shales are estimated to hold 6.6 million barrels of oil and about 2 billion cubic feet of gas.