LEASES · O-10-49245 · OIL · DISTRICT 08
Cox 12-9 Unit 1
ReportingDiamondback E&P LLC · Martin County · Spraberry (Trend Area) field
Cox 12-9 Unit 1 is an RRC oil lease (O-10-49245) in Martin County operated by Diamondback E&P LLC, with 13 wells completed on it.
It has reported 2.08M barrels of oil and 5.16M mcf of gas since August 2017, last reporting volume in April 2026 (statewide data runs through April 2026).
The last 12 reported months total 498K barrels of oil, down 39% on the year before; the lease peaked at 222K barrels in January 2025.
2 operators have filed production on it, most recently Diamondback E&P LLC since January 2025.
- 2.08M
- bbl oil, all reported
- 5.16M
- mcf gas incl. casinghead
- 498K
- bbl oil, last 12 reported
- -39%
- vs the 12 before
- 13
- wells completed on it
- 222K
- peak month, bbl (Jan 2025)
PDQ LEASE REPORTS · FIRST AUG 2017 · LAST VOLUME APR 2026 · STATEWIDE DATA THROUGH APR 2026
Oil by month
Barrels reported on Form PR for the whole lease. The latest months are revised upward as late reports arrive.
Last 12 months 498,220 · prior 12 818,801(-39%)
Gas by month
Gas-well gas plus casinghead gas, mcf. On an oil lease all gas is reported as casinghead. The latest months are revised upward as late reports arrive.
Last 12 months 2,481,154 · prior 12 1,502,229(+65%)
Decline curve
A MODEL FITTED TO THE REPORTS, NOT A REPORT
An Arps hyperbolic curve fitted to the 16 reporting months of oil since the peak in Jan 2025. The dashed line below is that curve, drawn over the months it was fitted to and then 24 months past the last report; where it parts from the columns is where the model stops describing the lease. It describes the trend of past reports. It does not know about recompletions, shut-ins, or new wells, and it is shown only when the lease reported within the last year and the curve explains most of the history.
- 86%
- first-year decline from the peak (nominal Di 426%)
- 0.7
- b factor (hyperbolic)
- 0.99
- fit R²
- 778K
- bbl remaining on the curve, to 1 per month
Oil, barrels reported months since the peak, with the fitted curve and its projection
Last 12 months 498,220
Fitted hyperbolic curve from the Jan 2025 peak, dashed 24 months past the last report
| Projected month | Oct 2026 | Apr 2027 | Oct 2027 | Apr 2028 |
|---|---|---|---|---|
| On the curve, bbl per month | 15,283 | 11,242 | 8,733 | 7,046 |
Quoting a projected figure as if it were reported would be wrong; the reported figures are the ones in the charts and the table view. How production is reported →
Who reported it
Each run of months one operator filed the production report, oldest first.
- Endeavor Energy Resources L.P.Aug 2017 → Dec 2024 · 89 mo
- Diamondback E&P LLCJan 2025 → Jul 2026 · 19 mo
Wells on the lease
FROM COMPLETION REPORTS · PRODUCTION ABOVE IS THEIR TOTAL
13
wells completed on the lease
- Shut IN
- 9
- Producing
- 4
Operates them now
About this data
Monthly oil, gas, and casinghead from the RRC PDQ production dump, which lags the reporting month by two to three months; figures shown through Apr 2026. Wells from completion reports; operator runs from who filed each month's report.
Developers: this page as JSON is GET /v1/data/leases/tx/o-10-49245, documented in the API reference.