Switching From Method 21 to Optical Gas Imaging in 2017


As current technology continues to improve over time, it becomes increasingly harder to stick with older, more tedious methods of leak detection and repair. With the rapid pace of improvement newer methodologies are undertaking, it wouldn’t be surprising to see entire industries shift and embrace more efficient alternatives.

Most oil and gas and petrochemical operations are still using Method 21, which was first developed by the EPA. What many companies might not know, however, is that OGI is becoming the increasingly preferred option by the agency. In 2015 the EPA issued a new proposal for reducing Methane emissions in which it identified optical gas imaging as the “best system of emission reduction” in terms of detecting methane emissions from new equipment installations, upgrades, and modified sources. The goal of the proposal was to reduce methane emissions from oil and gas production to be 45 percent lower than 2012 levels within the next ten years, and the agency decided OGI would play a significant role in that.

In 2016, the EPA issued the New Source Performance Standard (NSPS) Subpart OOOOa for regulating various emissions from the oil and natural gas sector. In the document, they laid out regulations that made semi-annual OGI monitoring for fugitive emissions mandatory for oil and gas well sites. Although Method 21 may be used as an alternative, the EPA had some restrictions in place on its use.

In the future, it wouldn’t be surprising to see OGI transition become the predominant LDAR method as Method 21 continues to grow more outdated. According to the EPA’s Leak Detection and Repair – A Best Practices Guide, elements of an effective LDAR program include identifying components, leak definition, monitoring components, repairing components, and recordkeeping. Optical gas imaging simplifies the first three, which are perhaps the most tedious of the entire process.

Regarding the efficiency of identification, OGI blows Method 21 out of the ballpark. A well-trained LDAR inspection team of two can monitor approximately 500-700 components per day. In comparison, optical gas imaging can monitor between 1,875-2,100 components in an hour. In this way, Method 21 is like trying to find a needle in a haystack in terms of identifying leaking components.

In one case study on the EPA’s website comparing Method 21 and alternative methods, it was shown that a medium-sized leak was identified six months earlier with OGI versus Method 21. The point to keep in mind is that medium-sized leaks are the equivalent of hundreds or even thousands of small leaks in terms of the volume of emissions produced.

Monitoring components are also much easier with OGI since the length of evaluations will tend to be much quicker. Having the need for a physical operator checking on every single component manually is a significant setback to operating under the Method 21 procedure. Although OGI may miss identifying the very small leaks, this is compensated by the much quicker identification of larger leaks, which as previously shown in the case study, has a far more significant reduction in total emissions.

Just because optical gas imaging might be a newer methodology doesn’t mean regulatory bodies don’t already respect it. With the EPA already having introduced numerous OGI stipulations in their regulations, the sooner companies are willing to make the switch, the better they will be able to adapt to future changes in emission litigation.