Thoughts on Methane

At a recent OOGA Trustees meeting I opined briefly about the natural geologic occurrence of methane and why we need to talk about it with friends outside our industry. The public knows it comes into their home through a pipe in the basement, from the utility company. We need to talk about Natural Gas (of which methane is the primary component) is our product product whenever and wherever the opportunity arises.

Methane is a naturally occurring byproduct of the decay of organic matter.

Where could we expect to find methane? Possible answers: around barnyards, at the dump, in the sewer...oh yes, and those wells scattered across the landscape.

Easy geology lesson. What is coal?. It is combustible black or brownish black sedimentary rock, comprised primarily of carbon. It is highly compressed organic matter (chock full of plant fossils as proof of its terrestrial organic genesis). So might we expect to find methane in, perhaps a coal mine? Yes (old rotten organic matter nets methane). How about in the soil and rock layers or aquifers surrounding a coal bed? Yes. Basically, in coal country (which a large portion of Ohio qualifies) where coal is “near” surface, should we expect to see methane in ground water? That is obvious.

Now what about shale? Virtually the entire state has shales at or near the surface. Shale is fine grained mix of clay particles and often contains organic matter. Shale’s blackness is the carbon derived from from the marine organic critters and plants that died and settled at the bottom of the vast deep sea. This is the reason shale and other related deep basin centered deposits are referred to as source rocks. Often, shales are the source of all the hydrocarbon in a basin. So again, would we expect to find gas in shale? Of course. How about in the aquifers in the proximity of shale (like the entire State of Ohio)? This too should be obvious.

Keeping these three things, the natural occurrances of methane, coal and shale when you are debating friends, family, store clerks, or whomever, and the discussion turns to “contamination” of water by methane, try to be the voice of reason. The presence of methane is simply proof of the working hydrocarbon system that has been here for hundreds of millions of years and that we have been developing for over 150 years.

Geochemical techniques to help guide exploration. Soil geochemistry, in simplest terms, works by measuring methane in the soil. If there is methane in the soil, it is most assuredly present in the aquifer. Often, wells are drilled on geochemical anomalies - in areas with high concentrations of methane in the soil (pre-drill). Higher concentrations of methane indicate a trapping mechanism is at work and that there is a deposit of natural gas at depth.

While the public may hear the soil and water is “contaminated” with methane, we should at every opportunity talk about what we know and what we do. We look for oil and natural gas in places we would EXPECT to find it... Methane in the soil or water isn’t the smoking gun of and spill, it is evidence of a working geologic hydrocarbon system.