P-18 glossary: skim oil, BS&W, LoneSTAR, and other terms
This glossary defines the terms operators meet on the Texas RRC Form P-18, the Skim Oil/Condensate Report, from skim oil and condensate to identifiable and nonidentifiable hydrocarbons, BS&W, LoneSTAR, and the Delegated Administrator role.
P-18 terms, defined
The P-18 carries a handful of terms specific to skim oil reporting and Statewide Rule 56. Here is what each one means in plain language.
- Form P-18
- The Skim Oil/Condensate Report: the monthly Texas Railroad Commission filing for facilities that recover and then sell or dispose of skim oil or condensate.
- Skim oil / skim hydrocarbons
- The oil and condensate that accumulate during produced water disposal operations and are skimmed off the water a facility handles.
- Condensate
- Light liquid hydrocarbons that condense out of gas or are recovered from produced water, reported alongside skim oil on the P-18.
- Scrubber oil
- Under Rule 56, the liquid hydrocarbons that accumulate in lines transporting casinghead gas and are captured at the inlet to a gas processing plant.
- Identifiable hydrocarbons
- Recovered hydrocarbons whose origin can be clearly identified when received at the facility. Volumes returned to the producing property in the same period are not reported, but require phone notice to the district office.
- Nonidentifiable (unidentifiable) hydrocarbons
- Recovered hydrocarbons that cannot be traced to a source. All nonidentifiable volumes recovered by a produced water disposal system are reported on the P-18, and unreconciled volumes can be exposed to seizure.
- Statewide Rule 56
- 16 Texas Administrative Code §3.56, “Scrubber Oil and Skim Hydrocarbons,” the rule that governs how recovered hydrocarbons are accounted for on the P-18.
- BS&W (basic sediment and water)
- The sediment and water content tracked on the revised P-18 as part of accounting for recovered volumes.
- Produced water
- Water brought to the surface with oil and gas, which saltwater disposal and water-gathering facilities receive, handle, and dispose of.
- Saltwater disposal (SWD)
- A facility that disposes of produced water, typically by injection. SWDs that recover skim oil file a P-18.
- LoneSTAR
- The Railroad Commission’s online filing system, where the P-18 can be submitted electronically since 2025.
- Delegated Administrator
- The person who manages a company’s LoneSTAR authenticated users and assigns filing rights, including P-18 access.
- Form T-1
- The Monthly Transportation and Storage Report, filed alongside the P-18.
- Reporting period
- The month a P-18 covers. The report is due by the 15th of the month following the reporting period.
Frequently asked
What does BS&W mean on a P-18?
BS&W stands for basic sediment and water, the sediment and water content tracked on the revised Form P-18 as part of accounting for recovered volumes.
What is the difference between skim oil and scrubber oil?
Skim oil is recovered during produced water disposal; scrubber oil accumulates in casinghead gas lines and is captured at a gas plant inlet. Statewide Rule 56 covers both.
What is LoneSTAR?
LoneSTAR is the Railroad Commission’s online filing system. Since 2025 the P-18 can be filed through it, with pre-populated data and a generated PDF.
Official sources
Emergent Environmental is not affiliated with the Railroad Commission of Texas. This guide is informational; the official P-18 instructions are authoritative.
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