What is an API number for an oil or gas well?

An API number is an identifier used in U.S. oil and gas well records. “API” in this context refers to a well-numbering convention, not a software application programming interface. The full source identifier and regulator context are important when joining permits, completion records, and well locations.

The Texas RRC · Online well records and identifiers describes its wellbore identifiers and Texas display conventions. Identifier formats and search requirements should be read from the source documentation rather than guessed from a number's length.

It is safer than a well-name match when connecting filings, production, and map records.

Keep the identifier as text. Converting it to a number can drop leading zeros or alter its display. Retain the original value alongside any normalized version used for a search. Record which formatting changes you made so the match can be checked.

Texas's online records guidance explains that its state code is often omitted in RRC document displays. A shorter displayed identifier is therefore not necessarily a different well. Conversely, similar-looking values from different jurisdictions should not be merged without establishing their full context.

A reliable join uses a documented relationship between those identifiers. The Texas RRC · Production Data Query FAQ explains why a Texas production search may require a lease identifier even when the researcher starts with a well API.

Start with the regulator and the identifier exactly as published. Confirm the well name, location, and operator as supporting evidence. Then use the source's linked records or documented crosswalk to locate permits, completions, and the applicable production entity.

If the well has multiple related records, preserve their labels instead of collapsing them into one row by name. An unresolved match is preferable to attaching production or a violation to the wrong well. Record the source query or document reference used for the match.

The number alone does not describe current status, production, reserves, ownership, or compliance. An identifier appearing in a permit application is not proof of a producing well. A persistent identifier can remain associated with records long after the operating condition has changed.

Do not use the identifier as a substitute for dated status information. When a source uses another well-identifier system, preserve that system's name rather than relabeling its identifiers as API numbers.

• Keep the source identifier as text, including leading zeros.
• Check the regulator-specific search format.
• Confirm location and well name as supporting evidence.
• Use a documented crosswalk before joining lease-level or operator records.