Effective Leak Detection and Repair Helps Minimize Methane Emissions

Leak detection and repair (LDAR) is essential in every upstream asset. This paper presents best practices and case studies about how LDAR can help to minimize methane emissions.

Flare for flaring associated gas. The end point of the pressure relief system on the oil facility.
Credit: Leonid Eremeychuk/Getty Images/iStockphoto.

According to the International Energy Agency (IEA), the oil and gas industry can achieve a 75% reduction in methane emissions with current technologies and up to 70% at no net cost.

Also according to the IEA, approximately 62% of the CO2 equivalent (CO2e) emissions comes from upstream activities. Fugitive emissions constitute the biggest single emitting source. Leak detection and repair (LDAR), therefore, is essential in every upstream asset. This paper presents best practices and case studies about how LDAR can help to minimize methane emissions.

LDAR programs have a long history with the Environmental Protection Agency’s Method 21 or optical gas imaging (OGI). LDAR is crucial to prioritize maintenance activities. Although some gas companies prefer OGI because of cost reasons, the more effective detection technique for all methane emissions is still using sniffing equipment photo ionization detectors (PID) or flame ionization detectors (FID). A comparative study indicated that only 71% of the bigger leaks with more than 262 kg/year emissions are found with OGI and only 5% of the smaller leaks. Moreover, quantification of the mass leaks becomes much more accurate with sniffing equipment compared with camera screening combined with leak/no leak factors.

A best-in-class approach is realized with an LDAR campaign that applies risk-based inspection considerations in combining measuring techniques such as FID/PID and OGI and frequencies referring to the probability of occurrence and consequence of emissions (e.g., source type, historical performance, stream composition).

Another best-in-class practice is situated around repair activities. While between 10 and 20% of new leaks are identified in every campaign, from 80 to 90% of the emitting sources were leaking in previous measuring surveys and have returned. The tightening of leaking gaskets and seals provides a temporarily better emission value of more than 90% reduction in only 62% of the repair attempts. Although a typical emission reduction improvement of 70% is achievable with a thorough LDAR program, more emphasis should go to in-depth problem-solving to avoid recurring leak sources. Examples include proactive mass replacement of certain gaskets or stem-valve seals during turnaround activities. This continuous improvement realized with these repair activities decreases fugitive emissions steadily.

Situations in which a yearly LDAR campaign has been omitted demonstrate a quick return to past emission figures. Executing LDAR fine-tuned to the situation is necessary to contribute to lower methane emissions and lower greenhouse-gas emissions in general.

Download the complete paper from SPE’s Health, Safety, Environment, and Sustainability Technical Discipline page for free until 28 July.

Find paper SPE 203169 on OnePetro here.