Three Environmental Defense Fund-affiliated studies this month make some pretty alarming claims about oil and natural gas methane emissions in the Permian Basin and Gulf of Mexico. But a closer inspection of the methodology behind these much higher than previously reported leakage rates shows that EDF is using calculations outside of the norm – some at odds with what the group has recommended previously – and they’ve been doing it for awhile.

Do As I Say, Not As I Do

Calculating methane emissions is a complicated task, and results can vary depending on how measurements are sampled, how often a site is evaluated, how large of an area is being sampled – they can even be influenced by time of day and weather. When researchers give a rate of methane emissions (intensity), what they are usually doing is calculating the total oil and natural gas methane emissions that they measured (or estimated for a region based on a smaller sampling) and dividing that by production.

There’s some debate on the amount of production to include in intensity calculations: Does it make more sense in an oil play to calculate intensity by total oil and natural gas production (barrel of oil equivalent) or only by total natural gas production? While there’s merit to both of these arguments, for the sake of consistency, EDF made its position clear on this in April 2018:

“Though there are different ways to calculate an upstream oil and gas intensity target, generally we recommend: Total methane emissions from oil and gas production / Total natural gas production.”

Or so it seemed.

Read the full post on EIDClimate.org.