HORTON DRAW PROSPECT
WASHAKIE COUNTY, WYOMING
Lloyd Blackburn, Exploration Geophysicist
The Horton Draw prospect is situated in Washakie County, Wyoming in T- 45- N; R- 88-W. This is in the extreme SE corner of the Bighorn Basin in a very sparsely drilled region. After evaluating the previous drilling in the area and investigating the surface geology, I made a recommendation to purchase 3 seismic lines which had already been shot in the area and I incorporated that data into my analysis.
My work so far suggests that there are as many as 4 separate types of hydrocarbon plays that can be made in the area. There is a Tensleep structural play to be made on the hanging wall of the anticline, a Tensleep structural play on the footwall part of the structure, a Tensleep erosional truncation play, and finally a Dakota channel play.
There have not been many exploration wells drilled in this part of the Bighorn Basin. The geologic control is limited in this part of the basin, so risks associated from lack of control are present. I believe that the best course of action at this point would be to acquire a 3D seismic survey to further delineate all of these plays so that a future drillsite could be chosen in the most efficient manner.
The Horton Draw prospect is located in the SE part of the Bighorn Basin. There is a well known geological feature named the Bud Kimball anticline that trends from NW to SE located in the heart of the prospect. This surface anticline is gently plunging to the NW and appears to line up with the producing structures at Bonanza, Nowood, and Manderson oil fields.
Oil & Gas map of the Horton Draw area
The most obvious exploration target in this part of the basin would be the Tensleep sandstone.
This is the most prolific reservoir rock in the entire basin and is the primary producer in the prolific fields to the NW. The Phosphoria formation is not prospective in this part of the basin since it is comprised of the evaporitic sequences similar to the Goose Egg formation of the Powder River basin. The Cretaceous section could be prospective but not from a conventional anticlinal trap, since everything from the Frontier down to the Sundance is exposed in the core of the anticline. However, there could be stratigraphic trapping in the structurally low areas in the Cretaceous.
The source of the oil in the Tensleep would be from the overlying Phosphoria formation. Although the Phosphoria is tight in this particular area, presumably the oil was generated in the deeper parts of the basin center and then migrated into the Tensleep and then up into the shallower structures.