Seismic activity used to analyze Barnett Shale
If you’ve noticed dozens of peculiar boxes with antennae attached, and funny white trucks driving around slowly in your neighborhood, don’t be alarmed – they’re not earth movers. Actually, they are.
The trucks and boxes are part of a monthlong seismic operation used to determine the “look” of the Barnett Shale formation thousands of feet below the Earth’s surface.
“The little white boxes that are distributed around are the recording stations for the seismic signals, and they are attached by typically an orange or a yellow cable to the vibrophone sensors right next to the curb in the residential areas,” said Wayne Hoskins, owner of Euless-based Map Snapper, the project manager for the operation. The boxes are spaced apart every 180 feet, “and they are recording the vibrations that are put out by the vibrator trucks that can be up to two miles away.”
A middle section from each of the three trucks drops slowly to the ground, lifting them slightly off the surface, and emits vibrations with a frequency range from 10 hertz to 120 hertz for eight seconds, then rests. The vibrations are picked up elsewhere by those recording stations, providing a picture, of sorts, of the shale below. Each episode takes about seven minutes to eight minutes to complete, Hoskins said, and then the trucks move to their next location.
The trucksÂ’ vibrations are felt within about 20 feet of the trucks during the process, but are hard to distinguish from any farther out.
There are two crews working currently: one on residential streets, and another off-road crew on larger tracts of land.
XTO Energy Inc. and Chesapeake Energy Corp. are paying for the operation, which covers 30 square miles and is being executed by Dawson Geophysical Inc., a Midland-based seismic data gathering firm. The company should complete the process around mid-August.
A hotline was established to help with curious residents, and the occasional episode where a recording box has been run over or a cable cut.
“Most of the calls, and we do get around 20 or 30 calls a day, are people just simply asking, ‘Gee, how long are these things going to be here?” Hoskins said.
At a recent survey on the corner of South and Norwich drives, a resident came outside to see what all the fuss was about. A crewman analyzing the signals nearby said most people donÂ’t have a clue what the trucks might be.
And as for all that duct tape used to keep the wires in their place?
“We buy it by the case,” Hoskins said laughing. “It’s just amazing, we had a half a tractor-trailer truck driven in on this project.”
Contact Tronche at jtronche@bizpress.net
