Rock Mechanics Manicure (Part I)

My cuticles are black, grime is buried so deep in the nail bed it won’t come out, and my hands feel like they’ve been through a meat tenderizer. For the past three days I sat in front of the drill press coring out my samples to take home for, well, exploding.

I had three days to get all the samples I needed for the next year’s research. The thrust of my doctoral work is to determine the tensile strength of shale by over-pressuring the pores with an inert gas. My rock samples will be surrounded with an impermeable layer — it could be something as simple as rubber cement — and nozzles on either end connected to gas lines. Then, I will flood the sample with gas, increasing the pressure until the rock breaks. I keep suggesting a violent explosion, but this makes others nervous, so I settled for the term fracture and mutter DYNAMICALLY! to myself.

Please note I said inert gas, not combustible or reactive.

Tech got me set up on the drill press and gave me a quick run through. I’ve used this type of equipment before, but every shop is different and this one had its quirks.

  1. The drill press came from the factory wired backwards. Since the users were used to setting it to reverse to drill forward, no one is going to change it.
  2. The water pump is also wired backwards, so that needed to be set to reverse as well. I’m left handed, so I told Tech that sounded right to me.
  3. The specimens need to be held by hand while coring. This drill press has no vise or clamps because none of the rocks cored are uniform (watch your fingers).

Not only is every rock is different, depending on their mineral composition the layers within each rock can be noticeably different to core. For three days, all I did was listen to the sound of the coring bit: too slow – no forward progress; too fast – the coring bit would bind and break. Listening constantly to the sound of the bit meant no music, no audio books. Just the sound of the coring bit making its way through clayey gray shale or silica rich black shale.

When breached with the bit, the gray shale smelled of sulfur. Sulfur smells in the the hydrocarbon world are not good because that means H2S, hydrogen sulfide. The rotten egg smell is the least of your worries as this gas is toxic. Starting at the 10 ppm mark H2S can knock a person out, cause brain damage or even death.

The amount found in this rock sample would not be enough to kill me, but a headache was forming so I bowed my head and prayed the only relevant prayer I could think of, The Sinner’s Hangover Prayer. Lord, please let the brain cells I just killed off be the stupid and useless brain cells. Let the intelligent and functioning brain cells remain… I desperately need those. Amen.


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