If the ground is shaking this week in Windsor, it’s likely not an earthquake, but vibrations used to create a 3-D survey of subterranean oil and gas deposits.
Geokinetics Inc. is working to create the survey for its client Geophysical Pursuit, which will compile the data to sell to oil and gas companies looking for the most cost-effective places to drill, Geokinetics Project Manager Bob Smith said.
To create the 3-D maps, Smith said the company deploys receiver stations every 220 feet, in lines running north to south, that pick up vibrations sent into the ground from special trucks as they move through town.
He said the company began deploying the receiver stations at areas in and around Windsor the last week of February.
“The little boxes are devices that record the vibrations picked up by the geophone sensors,” Smith said. “We generally have 11 or 12 receiver lines deployed before we bring in the vibrators. We work in between two receiver lines, shaking the source points as we go. As we complete the source points, we no longer need the first line, so we slowly start moving them west.”
The vehicles connect a baseplate to the pavement and generate controlled vibrations at pre-surveyed source points every 220 feet for about 5 minutes along the survey route.
Smith said some of the vibrating was done March 6 and the rest will be completed one day this week.
Boxes at the receiver stations record the data and store it until it is picked up and downloaded by the company to produce the 3-D map. Smith said the receivers would likely be removed by the end of the week.
“We’re close to the end of the job,” Smith said. “We’re almost done laying all the receiver points and then we’ll just be finishing up the shaking.”
Before the company could begin the survey in Windsor, Smith said they spent months filing hundreds of permits and getting permission from every surface and mineral property owner whose land they hoped to place sensors on within the 218-square-mile survey area.
“It’s a huge process,” Smith said. He said some of the property owners include conditions in the permit requesting to be called before the vibrating is done or that sensors not be placed in certain areas on their land.
He also said the town asked the company not to bring in their large vibrating trucks and use smaller vibrating trucks that are half the size and considerably quieter.
The company also held two public meetings where they demonstrated the equipment and explained the process to interested residents.
Smith said surveys like these are common in areas where oil and gas mining is prevalent. The data Geokinetics collects is valuable to companies trying to determine where the most cost-effective and best producing sites are for oil and gas exploration.
“We shot the whole city of Greeley last year,” Smith said. “It’s a common occurrence. We’ve been up here the past 3 years.”
The company maps areas where they know oil and gas companies are interested in drilling and try to tie new maps together with areas mapped in recent years to accumulate a large database of subterranean 3-D maps.
“That way geologists and geophysicists can look at it and pinpoint areas so they don’t waste money and time with low-producing wells.”
He also said the process is environmentally safe and that vibration levels produced in the survey aren’t forceful enough to cause any damage to structures.
“There are no environmental effects from what we’re doing, it’s completely harmless,” Smith said. “The vibrations are kept well below the level that might cause damage to a surrounding structure. That’s not to say you won’t feel the vibration though.”