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Seismic testing no great shakes

Seismic testing planned by natural-gas developers south of Silt this summer may be enough to send shivers up some people’s spines.But that may be about the worst they can expect, if projections by Bill Barrett Corp. hold true. The company plans to test areas it has under lease south of Silt this summer by using three-dimensional seismic testing. The goal is to pinpoint preferred drilling locations and avoid drilling dry holes. The testing area runs roughly from east of the Garfield County Regional Airport to about a mile or mile and a half east of Divide Creek, and from within Silt’s town limits south of the Colorado River, and heading several miles south.Barrett officials met with about 35 residents south of Silt this week to apprise them of the testing plans and try to show that the impacts would be minimal. The meeting, at the Garfield County Fairgrounds in Rifle, including a demonstration of the use of a “vibraseis” truck. Residents were ushered into the darkness of a parking lot where the truck operator noisily fired up its diesel engine. A testing pad of about 3.5 by 7 feet was lowered hydraulically from the truck center, pressing onto the ground until it nearly raised the truck off its oversized tires.The truck then vibrated the pad in perhaps a dozen bursts, each lasting several seconds. Golf balls that Barrett geophysical operations manager Mike FitzMaurice set out at 5 and 10 feet from the truck remained on their tees – except for one that fell because FitzMaurice had broken the tee in inserting it into the ground. Nearby, water rippled in a drinking bottle that FitzMaurice also had placed on the ground, but the bottle remained standing.From about 25 feet away, the testing felt akin to the shaking brought on by a bout with the flu, or by a coatless walk to the mailbox on a winter’s day. The noise of the diesel engine seemed like more of a nuisance than the vibrations – an assessment supported by Brit McLin, who lives near Barrett’s planned testing area and said he had experienced similar seismic testing work as a landowner living in California. Diesel engine noise was the greatest disturbance, and didn’t last long, he said.”It’s very uninvasive,” he said of the testing. “You don’t know it’s there. If you’re bothered by it you’ve got bigger problems than seismic testing. You need a hobby.”McLin said Barrett was wise to hold this week’s meeting, so people aren’t caught off guard when the work begins. McLin’s wife, Sharon, said she likes the idea of doing testing in an order to avoid drilling dry holes.”They’re a bad thing for everybody,” she said.Barrett officials say the surface disturbance associated with testing is less than what would result from drilling wells that don’t produce.The testing consists of using small explosives or vibraseis trucks to set off vibrations underground along grid patterns. Cables are run across the ground to sound receivers that record echoes coming back at angles from underground and transmit them to a recording vehicle. Measurements of reflection times can determine the depth and thickness of various rocks.The testing won’t show how much gas is underground. Rather, it will provide geological information about things such as whether natural fractures exist that would improve gas flow for wells drilled in certain areas. The underground testing is done in three dimensions, rather than in two-dimensional, vertical slices as with older technology. The result is better, more reliable data, FitzMaurice said.The entire testing project will be done on private land, so no federal permitting will be required. Barrett will need approval from the Colorado Oil and Gas Conservation Commission, Garfield County and the town of Silt.No permission is needed from private landowners to do gas exploration work such as seismic testing. However, “we intend to work with everybody here,” FitzMaurice said. “We don’t intend to just steamroll in.”Barrett plans to pay nominal access fees to landowners, and cover any damage to crops, he said.The company plans to start work in July, after irrigation season is over, and maybe complete it by September. The disturbance at any one residence shouldn’t last more than two or three days, FitzMaurice said.Barrett will avoid doing vibraseis and explosive work near springs and domestic water wells, and also will do no testing closer than 300 feet within archaeological sites. Barrett officials faced criticism for planning a similar testing project a few miles from archaeological sites in Utah but say they carried off the work without causing damage.It uses the vibraseis trucks wherever terrain allows, especially near homes because the trucks cause less vibration than explosives. The only damage the trucks do is to compress vegetation that will grow back, FitzMaurice said.The explosives consist of dynamite charges of about 5 to 20 pounds, Barrett officials say. Where explosives are used, holes will be drilled from trucks, from buggy rigs designed to leave virtually no track in more sensitive areas, or from helicopter-delivered equipment in areas that are hard to access. The drill holes are plugged, marked with stakes until the explosives are set off, and then covered back over.When the project is done, “We don’t want anybody to know we were there for the seismic work,” FitzMaurice said.Contact Dennis Webb: 945-8515, ext. 516dwebb@postindependent.com


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