A popular view is that the oil and gas industry is directly or indirectly responsible for a multitude of environmental sins – basically powering the Four Horsemen of the Apocalypse – it is probably time to try to put them into perspective. For starters, I’m going to look at methane and the position that methane emissions from oil and gas operations have in the big scheme of things.

Let’s start with a simple definition – Methane is a colorless and odorless gas. It is the simplest member of the paraffin (or alkane) series of hydrocarbons. Its chemical formula is CH4 (one carbon atom and four hydrogen atoms). It is lighter than air, burns readily in air, and is very slightly soluble in water.

Methane is accepted as one of the most damaging of greenhouse gases, being able to trap between 25 and 28 times more heat in the atmosphere than carbon dioxide over a 100-year period and, unfortunately, since 2007 its concentration in the atmosphere has been rising rapidly. However, on the plus side, methane only hangs around for about 12 years while carbon dioxide can linger for 30 to 90 years.

It is clearly a gas that needs a strategic focus when it comes to limiting emissions. The trouble is, methane comes from a wide range of sources and while the oil and gas industry is tagged as a major culprit with regulations now in place to demand that emissions be cut by up to 45% by 2025, it is hard to come up with exact figures one way or another. For better or for worse, this article is my summary.

First of all, let’s look at Old Mother Nature.

She is, all by herself, an extremely gassy old soul. Vegetable matter is readily decomposed by bacterial action with methane being one of the by-products. Research indicates that natural wetlands can produce up to 200 million tonnes or 200 teragrams (Tg) of methane per year. In addition, lakes, oceans, geological events, permafrost and the tiny, yet numerous termites, can produce around 130 Tg/yr. Also, the burning of vegetation, whether through natural or human action can add another 50 Tg/yr.

Secondly, once we have put as much blame on to nature as possible, we have the emissions of methane due to direct human action. These include agricultural activity, decomposition of the waste we leave behind, and yes, the oil and gas industry.

So. Agriculture. Man-made wetlands – rice paddies – produce about 110 Tg/yr. The kings and queens of agricultural animal methane emissions are bovines of various types, producing around 80 Tg/yr., 90% of which is burped out and the remainder coming from the rear-end. Apart from bovine burps and farts, there is also an estimated 25 Tg/yr. coming from their poo. Shifting back to Mother Nature briefly, I could not find a global number for methane emissions from the herds of gazelle, wildebeest, bison, etc. still wandering through or stampeding around the world’s grasslands – these animals are in the clear for now. If I find some relevant articles I’ll return to the subject and start pointing fingers.

What about our mess? Estimates for landfills suggest about 40 Tg/yr. of methane is produced.

Finally, what about the much-maligned oil and gas industry? Admittedly all of my figures are a couple of years old, but estimates indicate that around 95 Tg/yr. comes from oil and gas in one way or another, with around 40 Tg/yr. coming from the coal industry.

How does the oil and gas industry let so much methane into the atmosphere and why? Methane, is after all, a useful product used in the production of a number of organic chemicals and of course the main component of natural gas that keeps many a home-fire burning, home-stove cooking and power-station producing electricity for the folk who are not hooked up to gas.

One reason is that methane will naturally escape into the atmosphere when you drill an oil, gas, or any other deep hole in the ground. The gas is trapped in the rock’s pores until drilled into. It then either enters the mud-stream immediately or comes out of the rock cuttings as they are carried to the surface. At the surface this gas will head off into the atmosphere. A similar thing happens after fracking. The fracking fluids bring gas back to the surface where some is released fairly quickly, while more is slowly released from the returned fracking fluid as it sits in surface ‘ponds’ waiting to be recycled.

The other major reason comes down to accidental leaks along the way from wellsite to consumer. Based on the areas of concern in the Environmental Protection Agency (EPA) regulations, emissions will have to be monitored from wellheads, gas gathering systems, various compressors, pumps and pneumatic controls and pipelines.

To sum up then, the league table of methane polluters looks like this:

  • Mother Nature herself = 350 Tg/yr.
  • Agriculture = 215 Tg/yr.
  • Oil, gas and coal = 135 Tg/yr.
  • Human refuse (landfills) = 40 Tg/yr.

Mother Nature does however, go a long way to compensate for her output of gas. Two major methane sinks include the atmosphere which breaks down methane at about 580 Tg/yr., and the soil which breaks down another 40 Tg/yr.

Doing the sums, this obviously shows that we need to cut back by about 120 Tg/yr.  Mother Nature does her best to clean up humanity’s gas problem but, as with carbon dioxide emissions, we will need to help out just a little.  The oil and gas industry needs to cut up to 45% by 2025 (unless the rules change) so that will help by just under 50 Tg/yr.  We may be able to do better!  For the rest, well, a large part of the world’s population could decide to stop eating rice or the bovine population could be taught some manners.

I will look at some of the solutions in a future article.  Hold your noses and watch this space…

About The Author Geoff Cave

I have a degree in geology from the University of Cardiff in Wales. The degree is itself almost geologic. I entered the workforce in 1977 as a mud-logger and have since taken on many roles unassociated with the finer science and art of geology. I lived and worked on oil rigs in Brazil, Venezuela, Colombia, Chile, Nicaragua, Guatemala, Mexico and Trinidad & Tobago for the first 20 years of my career and in the subsequent 20 years I have been an instructor in oilfield familiarization – rigs, drilling, geology, engineering, pressure evaluation etc. - and a product, marketing and business manager for the multiple disciplines in a mud-logging service company. I am currently considering what to do next and hoping that someone will soon provide an answer.