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Editor's note:

This month's Q&A is a lot like that old story about what happened when your young child first asked you, "Where did I come from?"

You probably relied on all of your knowledge and experience, explaining in great (and delicate but overwrought) detail about the entire concept of "a man and a woman liking each other a whole lot" and then getting really, really scientific.

And then, when you're finished, your child says: "Oh, well ... Joey came from Toledo."

Sometimes the obvious questions are the ones that geoscientists work too hard to explain.

So, remember: These Q&As aren't really for you. They're for you to use when someone who is not a geoscientist assumes you can answer a simple question with simplicity and clarity.

Q&A: All Gas Is Not Created Equal

So How's the Propane Well Doing?

Question: Is it possible to drill for propane, butane or methane?

Short answer: People do it all the time.

Methane is the largest component of what we call natural gas.

Propane and butane also are gases, and may be found in smaller amounts in natural gas.

Because of their value as fuel and their high energy content per cubic foot -- about 2,500 Btu for propane and 3,250 Btu for butane -- they're often separated from the gas stream and sold as natural gas liquids.

By contrast, methane has just over 1,000 Btu per cubic foot.

For added confusion, the second-largest component of natural gas after methane is called "ethane." Ethane also could be liquefied and sold as fuel, but it's more commonly used as a feedstock for petrochemicals.

Natural gas liquids are the opposite of unnatural gas liquids (just kidding). They are often referred to as NGLs (that's true).

Propane and butane don't occur naturally in separate, large accumulations, so there's no such thing as drilling a propane well or a butane well.

Not that long ago, NGLs were much, much more valuable than high-methane natural gas, relatively speaking. Some operators justified their drilling programs by the amount of NGLs they expected to generate.

So, in that sense, it is possible to drill where you plan to recover more-than-usual amounts of propane and butane.

-- DAVID BROWN

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