Herndon 1A O'Leary
API 4004105002 · Dewey County, South Dakota · Wildcat field
Plugged and AbandonedDry Hole
API
4004105002
Operator
Herndon Drilling Co.
County
Dewey
Field
Wildcat
Location
Permit
164
Formation tops
South Dakota records 10 formations for this well, shallowest first.
| Formation | Top (ft) | Age |
|---|---|---|
| Niobrara Formation | 1,600 | Cretaceous |
| Greenhorn Limestone | 2,150 | Cretaceous |
| Dakota Mud | 2,687 | Cretaceous |
| Piper Formation | 3,187 | Jurassic |
| Charles Formation | 3,990 | Mississippian |
| Mission Canyon Limestone | 4,052 | Mississippian |
| Three Forks Shale | 4,650 | Devonian |
| Jefferson Group | 4,750 | Devonian |
| Stony Mountain Formation | 4,995 | Ordovician |
| Red River Formation | 5,041 | Ordovician |
A dash is a formation South Dakota records for this well without a depth.
Completion
South Dakota files 1 completion report for this well.
Vertical Well
Plugged and AbandonedDry HoleSpudded
1955-10-03
Measured depth
5,147 ft
True vertical depth
5,147 ft
Location
45.256610, -101.253810
45.25661, -101.25381 · Surface location as filed with South Dakota⌘ or Ctrl + scroll to zoom
Every well in Dewey County, South Dakota
South Dakota state record, from SD_wells_SDOILexport_Export__wells_Table_4_Web.parquet. Corpus built 2026-09-11.