Recently I was a guest at an oil-gas well frac-ing (Process of fracturing the down-hole rock formations). The location was way out in west Texas not far from a little town of Pyote. This was my first experience at a well during drilling or under development.
I did some preliminary research on what I might see, and that was very helpful in understanding the tour. The tour lasted about one hour, but seemed much shorter. I was amazed at all the infrastructure in place.
If you want to read more on frac-ing, then head on over to frac-ing at Wikipedia. The description there is pretty much spot on.
The well in question is very deep, drilled down about 12,000ft and then out horizontally to about 4,000ft.
The multi step process.
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1) a series of explosives located along a special piece of drill pipe are lowered and then pushed (in the horizontal section) to the desired position. This section of drill pipe may be 48ft or longer, and the explosives are grouped in batches along about 12ft. Electric wires to trigger the shots run up to a control center at the surface. Once in place at its lowest position, the lower set of shots are fired, and the drill pipe is raised about 12ft or more to the next target zone. this process continues until all shots are fired, and the pipe is brought back to the surface.
2) a complex plug, about 3ft long, is sent down hole and is locked at the lower point of the area to be fractured.
3) a slurry of water and proppant (tiny balls of Aluminum Oxide – smaller than the ball in a ballpoint pen) is pumped at high pressure down the well. This slurry can contain several other chemicals to improve efficiency (such as surfactant) and measurement (isotope tracers). I don’t think there were any tracers used at the site I visited. The slurry is pumped down at a continuous high pressure. This can be 7,000p.s.i and greater. Once started, it needs to continue until certain flow rates/pressure changes are detected in the elaborate control center at the surface.
The aim of the process is to open up small fissures in the rock formations below, to allow greater flows of hydrocarbons into the well. This can lead to better economies and return on exploration and development investment.
The Site
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The Equipment
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Water Tanks
More Water Tanks
Did I mention Water Tanks?
I would estimate there were 60 or more tanks of different shapes and sizes. Water is critical to the process and must not run out during frac-ing. It is stockpiled in readiness to the commencement and then a steady stream of water trucks will deliver more during the process.
The Proppant
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The proppant is stockpiled and there were several large tanks loaded with the substance. The tanks were very similar to the water tanks, but are closer to the slurry mixer and pumper trucks.
This shows one of the trucks that delivers the proppant.
The Pumper Trucks
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There were about 10 of these monster trucks, parked 5 abreast in two rows, each row backing up to the other row. This area was out-of-bounds due to running machinery and noise.
Shot Firing
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This truck is the logging and firing control center.
Here you see the crew arming the explosive charges in the drill pipe, ready to send it down the hole. No cell phones or walkie-talkies in this area!
A partial length of the explosives pipe. It will be more than twice this length when ready for lowering and firing.
Multi Function Pipe Truck
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This truck manages a giant spool of 2inch steel piping. The pipe is a single length of about three miles long. One use is to push the bottom plug down the hole and around the bend where the hole heads off horizontally. As mentioned earlier, this horizontal section is about 4000ft long. The well head can be seen to the right of the photo, as well as in the next…
That pretty much ends the tour. There was one other interesting truck which was not photographed. This was the main control center for the mixing and pumping operations. Mounted on another large truck, it housed around four technical operators controlling such things as water transfer pumps, the slurry mixers and ingredient controls, and the ten large pumper trucks. Lots of computers and screens to monitor in the operations room.
Thanks go to David H Arrington Oil and Gas of Midland, Tx and to Halliburton of Houston, Tx and their staff.
John Griffiths
