FORMATIONS · RRC WELLBORE FILE
Duffer
Reported as a top in 2,587 wells across 19 counties, at a median depth of 3,850 ft (3,110 to 4,171 ft in most wells). 4 of those wells were permitted in the last three years.
A well counts if any of its completion filings report this formation, whether it produces from it or drilled through it. Depths are measured depth as filed; typo depths exist, which is why ranges are percentiles, not extremes. About completion reports →
- 2.59K
- wells reporting a top
- 4
- permitted in last 3 years
- 19
- counties
- 3,850
- median top, ft
COMPUTED OCT 29, 2026 · REBUILT DAILY
Depth by county
Counties with at least five wells reporting the top. Bars are well counts.
| County | Wells | Median, ft | P10–P90 | Last 3 yrs |
|---|---|---|---|---|
| Stephens | 892 | 3,980 | 3,846–4,124 | 3 |
| Eastland | 795 | 3,690 | 3,260–3,876 | 1 |
| Brown | 179 | 2,910 | 2,192–3,185 | 0 |
| Callahan | 137 | 3,852 | 3,703–3,954 | 0 |
| Palo Pinto | 109 | 3,659 | 3,383–4,120 | 0 |
| Shackelford | 103 | 3,975 | 3,821–4,410 | 0 |
| Erath | 85 | 3,838 | 3,216–4,450 | 0 |
| Comanche | 65 | 2,931 | 2,684–3,125 | 0 |
| Hood | 57 | 4,686 | 4,171–5,231 | 0 |
| Coleman | 51 | 3,295 | 2,540–3,368 | 0 |
| Parker | 41 | 4,390 | 4,036–5,500 | 0 |
| Johnson | 30 | 5,257 | 5,162–6,219 | 0 |
| Young | 16 | 4,275 | 4,066–4,708 | 0 |
| Throckmorton | 14 | 4,406 | 4,280–4,525 | 0 |
| Somervell | 5 | 4,948 | 4,925–5,008 | 0 |
Operators
Current operator of record for wells reporting the top, ranked by wells permitted in the last three years.
Recently permitted wells reporting the Duffer
BY LAST PERMIT ISSUED
About this data
Formation tops, elevations, perforations, and casing from the RRC dbf900 wellbore file, refreshed weekly, with reported names normalized to Petrora's formation registry. County and operator breakdowns are rebuilt nightly.
Developers: this page as JSON is GET /v1/data/formations/duffer, documented in the API reference.