Up and Coming Weekly is a weekly publication in Fayetteville, NC and Fort Bragg, NC area offering local news, views, arts, entertainment and community event and business information.
Issue link: https://www.epageflip.net/i/18418
Does Oil Drilling Cause Sinkholes? From the Editors of Environmental Magazine What, if anything, fills the empty space under- ground created by the extraction of billions of gal- lons of oil? Could oil drilling be one of the causes of increasing amounts of land settling and sink- holes in oil rich areas? Can it cause earthquakes? — Linda Anderson, Sedona, AZ The crude oil (and natural gas) we drill for the world over is, for the most part, stored in tiny pores within rock up to only about three miles deep in the Earth’s hugely dense crust. At such depths, the oil there is under fairly high pres- sure. When it is removed, other liquids — usually water — move in to take its place, equalizing the pressure in the process. Sometimes oil extractors pump water into one side of an oil field to push oil toward wells on the other side, and the water replaces the oil accordingly. In cases where other liquids don’t move in, such as in the North Sea off The Netherlands, the porous rock layer that harbored the oil originally can col- lapse after extraction, causing slight amounts of land settling (known as “land subsidence”) in the rock layer surfaces above, but typically no more than a few tenths of an inch per year. Here in the U.S., land subsidence induced by the large volume extrac- tion of underground resources including oil and gas “is more common than most people realize,” according to the U.S. Geological Survey (USGS), a government agency which collects, monitors, analyzes and provides scientific understanding about natural resource conditions, issues and problems. Flat coastal plains and wetlands near sea level are most at risk from this potential side effect. Excessive ground water pumping, not oil or gas extraction, is the single largest source of land subsidence, says the USGS, but the agency cites sev- n adin “The U.S. Geological Survey cites several cases throughout the 20th century which they say demonstrate how accelerated withdrawal of oil and gas from some reservoirs can lower land elevation, cause minor earthquakes and activate faults around oil fields.” Image by Richard Masoner, courtesy Flickr. eral cases throughout the 20th century which they say demonstrate how “accelerated withdrawal of oil, gas and associated water from shallow uncon- solidated reservoirs could lower the land eleva- tion, cause minor earthquakes, and activate faults [around oil fields].” Subsidence around large, mature oil and gas fields that coincide with faults could add enough stress to trigger small, locally based earthquakes as far as two kilometers away from the offending wells. Most geologists agree, though, that it is un- likely that oil and gas extraction could contribute to or cause major earthquakes, which are generated at depths far deeper than would be practical to drill for oil or gas. The USGS does suggest, however, that the continued withdrawal of oil and gas and the associated decline in underground fluid pres- sure could even contribute to coastal sea level rises by lowering coastal land elevations. As for sinkholes, modern oil wells tend to be much deeper than the depth where sinkholes typically can affect people. Nonetheless, in 1980 residents of the West Texas town of Wink awoke one morning to find a 370-foot wide, 110-foot deep sinkhole a couple of miles north of downtown. Geologists suspect the sinkhole formed as a result of historic (and by today’s standards outdated) oil production practices in the area whereby extractors pumped salt- water out from underneath the surface and left a void that the above layer of earth eventually collapsed into. A second, even bigger sinkhole opened up nearby in 2002. CONTACT: U.S. Geological Survey, www.usgs.gov. SEND YOUR ENVIRONMENTAL QUESTIONS TO: EarthTalk®, c/o E – The Environmental Magazine, P.O. Box 5098, Westport, CT 06881; earthtalk@ emagazine.com. E is a nonprofit publication. Wiley’s Grille & Bar at the Holiday Inn Bordeaux. NFL Football game this season at Wiley’s! Catch every *Lunch Buffet M-S 11-3 Closed Sunday b Fine Dining Mon - Sat 5-10 Full Service Bar • Large Parties • Catering • Take Out Reservations Accepted “Exquisite Indian cuisine prepared by a world renowned chef.” 3401-A Raeford Rd. (Formerly Pierro’s) Next to All American Freeway 433-4351 • shalimarfaync@yahoo.com 20 UCW OCTOBER 27 - NOVEMBER 2, 2010 www.hibordeaux.com 1707 Owen Drive 910-323-0111 or 800-325-0211 OPEN DAILY FROM 4 P.M. - MIDNITE, GRILLE OPEN 4:30 - 11 P.M. Kick off a great season of NFL Football at Wiley’s Grille and Bar. In addition to two big-screen TVs and 11 additional TVs for your NFL Football viewing pleasure, you’ll enjoy great food and beverage specials all season long. WWW.UPANDCOMINGWEEKLY.COM c A i r W e o px lr E d en Cl isi Halal Meat Non-sa Vegeta Vegetarian & eget egetarian ria *Items Change Daily! NOW OPEN ms C ms Cha g D ily! ms Ch Daily C u I e n e