Compliance

Leak Detection and Repair: LDAR Programs for Oil and Gas Facilities

Leak detection and repair, or LDAR, is the work of finding small fugitive emissions before they become big ones. Valves, connectors, pumps, compressor seals, and tank hatches all release volatile organic compounds and methane over time, and a facility that never looks for those leaks is quietly losing product and building a compliance problem. LDAR turns that into a routine: find the leak, tag it, fix it, verify the fix, and write it down.

What LDAR means

LDAR stands for leak detection and repair, and the name is the whole job. A leak is any component that releases volatile organic compounds (VOCs) or methane into the air at a rate above the threshold set by the rule that applies to the facility. The components in play are the ones that see pressure, motion, and wear: control valves and their packing, flanges and connectors, pump and compressor seals, pressure relief devices, open-ended lines, and thief hatches on tanks and vessels.

The emissions matter twice. VOCs are air pollutants that help form ground-level ozone and carry toxics like benzene, and methane is a strong greenhouse gas that is also the product being sold. A leaking thief hatch on a stock tank can lose more gas than a dozen worn valve packings, which is why tank battery sites are usually a focus of any survey. LDAR is a closed loop: survey, tag, repair, verify, and record. Skipping any step weakens the rest, because the record is what proves the work happened. Good housekeeping on the well side reduces the number of components a survey has to check; see the wellhead maintenance best practices guide.

Where the requirement comes from

The federal anchor is the New Source Performance Standards (NSPS) under the Clean Air Act, found in 40 CFR Part 60. EPA has issued several subparts for oil and natural gas: Subpart OOOO for facilities built in recent years, Subpart OOOOa for a later group, and the newer methane rules that extend the same ideas to more equipment and add survey and repair requirements. These standards apply to facilities that are new, modified, or reconstructed after the applicable date, so an older well with untouched equipment may not be covered by the federal rule at all, while a new compressor station is covered from the day it starts up.

State rules layer on top. Most producing states have their own air regulations, and many of them reach further than the federal baseline: stricter survey frequencies, different thresholds, or coverage of existing facilities that NSPS never touched. Two sites in different states can face different numbers and different deadlines on the same kind of equipment. The practical habit is to assume both layers apply and check state rules before planning a survey schedule. The rule that drives much of this work is explained in the EPA methane rule for oil and gas operators guide.

How a survey works

A survey is a walk through the facility with the equipment list in hand. The two standard tools are optical gas imaging (OGI) and Method 21 screening. An OGI camera makes a plume of gas visible on screen, which lets a trained operator scan a long stretch of piping quickly and spot a leak without touching every fitting. Method 21 is instrument-based: a portable analyzer with a probe is moved along each component seal, and the reading is compared against the threshold for that component type. Many programs allow OGI as the survey method for most components, with Method 21 kept for verification and for components that cannot be seen clearly.

The route follows the process: in at the wellhead or inlet, through separators and heater treaters, along the compression, and out past the tanks. Every component on the survey list gets checked or explicitly skipped and noted. When a leak is found, it gets a tag with a unique ID, the date, and the reading; the same ID goes into the survey log so the leak can be tracked until it is repaired and rechecked. Speed is the point of the walk: faster coverage means surveys can run more often, and frequency catches small leaks before they become reportable. Compression sites deserve extra attention because seal failures are common there; the gas compression equipment guide covers the failure points.

Leak thresholds and repair deadlines

A component becomes a leak when its measured concentration crosses the threshold for its type under the applicable rule. Thresholds differ by subpart, by component type, and sometimes by the method used to measure, so there is no single number that works everywhere. What matters on site is the number in the rule that applies to that facility, written down and easy to reach when the survey crew is out walking.

Once a leak is identified, the repair clock starts. The rules generally require a first repair attempt quickly, a full repair within a set number of days, and a re-survey to confirm the fix holds. The deadlines also recognize reality: if the parts are not available, or the repair requires shutting down a unit that cannot be shut down without emptying the process, an operator can delay the repair, but only with written justification and an approved plan. The discipline that keeps a facility out of trouble is simple: do not let a tagged leak drift, and never let the repair slip past the date the rule allows.

Keeping the records straight

The survey is only half the compliance work; the record is the other half. The core documents are the survey log, the repair ticket, and the report. The survey log lists every component checked, the date, the technician, the method, and the result. The repair ticket records what was found, what was done to fix it, when the work happened, and the verification reading that confirms the leak is gone. Many programs also require periodic reports, commonly quarterly or annual, that summarize survey results and repair activity for the agency.

Records should live where they cannot be lost: named consistently, kept for the full retention period the rule requires, and available to the survey crew, not just the person who files. Survey findings and repair tickets, closed out in the same system, are what software like OpsFlo keeps, tracking tickets, dispatch, approvals, timesheets, and documents so the field record matches the file record.

Sources and further reading

• EPA: Controlling air pollution from oil and natural gas operations
• eCFR 40 CFR 60 Subpart OOOOa: Crude oil and natural gas source category