TEXAS · WELLS · ATASCOSA COUNTY · API 42-013-34306 · DISTRICT 01
Hierholzer Unit #1H
Atascosa County · Eagleville (Eagle Ford-1) field · Producing · Horizontal
Hierholzer Unit #1H (API 42-013-34306) is a horizontal well in Atascosa County operated by Marathon Oil EF LLC, completed June 17, 2010 and listed as producing on the RRC schedule.
The RRC has issued 2 drilling permits (amended once) between 2010 and 2012, permitted to 10,495 ft.
Completion filings report 3 formation tops, including Anacacho, Austin Chalk, Eagle Ford.
Its 2 leases have reported 142K barrels of oil and 109K mcf of gas since May 2010, last reporting volume in March 2026. The leases carry 2 wells, so these are lease totals, not this well alone.
Operator of record
- Based in
- Houston, TX
- P-5 status
- Active (A)
- P-5 last filed
- Sep 26, 2025
- Permits on file
- 3,191
- Phone
- (832) 486-2737
SOURCE · RRC EWA WELLBORE SCHEDULE
What each RRC source says
| Wellbore schedule | Marathon Oil EF LLC |
| Production reports | Marathon Oil EF LLCthrough Mar 2026 |
| Latest permit | Marathon Oil EF LLCMay 17, 2012 |
- 10,495
- total depth, ft
- 3
- permits on file
- May 17, 2012
- last permit issued
- Jun 17, 2010
- completed
- 142K
- cumulative oil, bbl
- 109K
- cumulative gas, mcf
PRODUCTION FROM PDQ LEASE REPORTS · Nov 2010 THROUGH Mar 2026
Regulatory status · RRC wellbore file
- Schedule
- ON SCHEDULE
- Completed
- Jun 17, 2010
- Shut in
- —
- Plugged
- —
Operator's P-5 on the schedule: Active – Extension (X)
Surface location
No coordinates on the permit record yet. The RRC's GIS record usually lands within days of issuance; historical master-file permits never carry one.
Lease production
PDQ LEASE REPORTS · REPORTED THROUGH APR 2026
Texas reports oil by lease, not by well. These are the 2 leases this well is completed on; they carry 2 wells in total, so volumes are shared.Why →
| Lease | Field | Reporting operator | Wells | Oil, bbl | Gas, mcf | Reported |
|---|---|---|---|---|---|---|
| Hierholzer Unit O-1-15669 | Eagleville (Eagle Ford-1) | Marathon Oil EF LLC | 1 | 135K | 104K | Dec 2010 – Mar 2026 |
| Hierholzer Unit O-2-9801 | Eagleville (Eagle Ford) | Marathon Oil EF LLC | 1 | 7.75K | 5.14K | May 2010 – Nov 2010 |
Oil, barrels lease total
Last 12 months 363 · prior 12 1,852(-80%)
Gas, mcf lease total
Last 12 months 1,223 · prior 12 1,386(-12%)
Chain of custody
Every operator that reported production on this well's lease, in order.
- 1Hilcorp Energy CompanyNov 2010 → Nov 2010
- 2Marathon Oil EF LLCDec 2010 → Jan 2026
Permits
| Permit | Type | Operator | Received | Issued | Spud | Depth |
|---|---|---|---|---|---|---|
| 739574-99 | Recompletion | Marathon Oil EF LLC | Apr 30, 2012 | May 17, 2012 | May 27, 2010 | 15,786 |
| 696455-98 | Drill | Hilcorp Energy Company | Sep 15, 2010 | May 25, 2010 | May 27, 2010 | 13,500 |
| 696455-99 | Drill | Hilcorp Energy Company | May 24, 2010 | May 25, 2010 | May 27, 2010 | 13,500 |
Completions
| Completed | Lease | Field | Operator | Status | Depth |
|---|---|---|---|---|---|
| Jun 17, 2010 | Hierholzer Unit O-1-15669 | Eagleville (Eagle Ford-1) | Marathon Oil EF LLC | Producing | 10,495 |
| May 27, 2010 | Hierholzer Unit O-2-9801 | Eagleville (Eagle Ford) | Marathon Oil EF LLC | Not on Schedule | — |
Formation tops
As filed on W-2/G-1. Subsea from 429 ft elevation.Download CSV →
| Formation | MD ft | Subsea |
|---|---|---|
| Anacacho | 10,390 | -9,961 |
| Austin Chalk | 10,527 | -10,098 |
| Austin Chalk | 10,535 | -10,106 |
| Eagle Ford | 10,692 | -10,263 |
| Eagle Ford | 10,740 | -10,311 |
Perforations
Perforated and open-hole intervals.
| From | To | Type |
|---|---|---|
| 10,610 | 10,808 | Open hole |
| 10,610 | 15,474 | Open hole |
| 14,729 | 15,634 | Perforated |
Casing
Strings as reported, shallowest first.
| Casing in | Set at | Hole in | Cement |
|---|---|---|---|
| 9.625 | 5,290 | 12.25 | 1,930 S |
| 5.5 | 9,927 | 8.5 | 1,660 S |
| 4.5 | 15,786 | 8.5 | 855 S |
Completion filings
W-2 and G-1 reports on record in the RRC wellbore file, newest first. The suffix identifies the wellbore or completion event. The record date is the RRC's own date on the record, not the day the report was filed: 462,034 of the state's filings carry 1984-01-12. About these reports →
| Suffix | RRC record date | W-2 / G-1 date | Logs referenced |
|---|---|---|---|
| 00 | Jun 11, 2013 | Jun 26, 2012 | — |
| 00 | Apr 4, 2012 | May 23, 2011 | Yes |
| 00 | Mar 2, 2012 | May 23, 2011 | Yes |
The source documents
Petrora holds the structured record. The scanned filings live at the RRC; these links open its search already filled in for this API.
- Wellbore filings for 42-013-34306 → W-2, G-1, plugging reports, as PDFs
- Completion packets for 42-013-34306 → scanned completion filings
Log images filed since 2004 open from the RRC's log search for this well; none are loaded here for it.
About this data
Permits from the RRC OGA049M master and daily daf420 files; wellbore and operator of record from the EWA schedule, weekly; completions, formation tops, casing, and perforations from the dbf900 wellbore file; production from PDQ lease reports, which lag two to three months; injection from UIC permits, H-10 reports, and TexNet daily volumes; earthquakes from the TexNet catalog.
New to these records? How to read a well page · API numbers · completion reports and tops · why production is by lease
Developers: this page as JSON is GET /v1/data/wells/01334306, documented in the API reference.