Tonye Princewill

November 25, 2011

A natural gas primer

A natural gas primer

Prince Tonye Princewill
NATURAL gas is in the news again—ushered in on a new wave-crest of conflict and controversy, arising from the Federal Government’s extension of the deadline for extracting firms to end gas flaring to December, 2013.

My original intention was, in fact, to write about the politics of flaring: Which is the wasteful burning of natural gas by igniting it atop tall metal chimneys. More gas is flared in Nigeria than anywhere else in the world.

According to an Internet paper authored by Albert Sei, Edmunde Merem and Yaw A. Tumasi, the rate of gas flaring in Nigeria is 15 times the world average and four times that of all the Organisation Petroleum Exporting Countries, OPEC, combined.

Flares light up the night sky throughout the Niger Delta, creating an eerie reddish-orange or yellowish hue over many cities and villages.

Yet casual inquiries, to test the knowledge of a few individuals around me, yielded surprising, and rather sad, results: Virtually no one could tell me, with any degree of exactness, what “natural gas” is.

Sure: Almost everyone could associate the term with cooking gas; and they know natural gas is in some way related to oil extraction.

Any effort to press beyond this point though, to something approximating a scientific definition, drew a blank stare.

I still plan to explore gas flaring and its implications. But this particular column is intended as a primer, to properly introduce the subject.

Reflected here, of course, are my personal sensitivities and concerns—both as a petroleum engineer, with a specialized knowledge of the subject, and a politician in a gas producing region.

Operative, as well, is an awareness that our education system has virtually collapsed. Accordingly, I write in deference to teachers, students and, of course, parents who might need to be refreshed.

Natural gas provides 23 percent of the world’s energy needs. It is the cleanest and cheapest form of hydrocarbon energy.

Nigeria’s natural gas reserves are estimated at some 260 trillion cubic feet. This is more than three times the size of the nation’s oil deposits. It makes Nigeria’s gas deposits the 10th largest in the world.

What is natural gas?

Well, let’s begin by distinguishing a “gas” from other types of common matter. I insert the qualifier “common” because there are not only solids, liquids and gasses but also plasma—often called the “fourth state” of matter.

A gas is the most fluid and the least viscous form of matter. Its atoms and molecules are much farther from each other than those of solids and liquids—so far, that they interact electro-statically rather physically.

It is temperature that determines whether a particular kind of matter exists as a solid, liquid, gas or plasma. Changing matter from a solid to the other three states, require increasingly high temperatures. Only plasmas require a higher temperature than gases.

All known types of matter expand when heated. But gases are unique, in that they have the capacity to expand indefinitely (which creates some special challenges for the natural gas industry).

Examples of gasses are the air you breathe, clouds and steam rising from boiling water. Steam is also known as “water vapour”.

Natural gas too, is a kind of vapour. It is the vapour given off as plants and animals decay deep underground, where they are subjected to intense heat and pressure for millions of years.

During this time, plants and animals, encased in certain types of rock formations, decay to become coal (in the case of plants) or the viscous brown or black substance we know as crude oil (in the case of animals). Consequently, natural gas is associated with both coal and oil deposits.

But not all natural gas deposits are associated. Under certain conditions, the vapour will separate and be preserved in a liquid or gaseous state, to form a non-associated condensate deposit or gas well.

Qualitatively, there is what petroleum geologists and geophysicists call “sweet gas”. This refers to a vapour residue that does not contain hydrogen sulfate, while gas in which this caustic agent is found is termed “sour”.

Chemically, natural gas consists primarily of methane (CH4) in combination with various hydrocarbons, such as propane (C2N8), butane (n-C4H10), ethane (C2H6), etc. Helium, nitrogen, mercury and water are also common by-products.