First of all, what is re-fracking? We know that fracking is a method in which water-based fluid under extremely high pressure is pumped down a well to fracture the reservoir rock next to the well bore, creating pathways for natural gas to flow to the wellhead. Through new technology we’ve learned some wells are re-completed and fracked to enable production from a second layer or to open fractures that may have closed over time. A well may be re-fracked every one to two years of operation to stimulate production.
Re-fracking is currently sweeping the country in many shale basins due to the quick declines in oil and gas output. Several oil companies, including Canada’s Encana Corp., Exco Resources Inc. and Marathon Oil Corp. are using new re-fracking techniques at older fracking wells to bring new life back into them.
Using diverting agents (minuscule plastic balls), pumped at high speeds with water into the 3 to 5 year old wells, Encana blocked some of the older fractures, or cracks. “The thought is that the diverting agent will go to the cracks with the least amount of pressure, bypassing cracks with higher pressure and boosting the pressure of the entire well so output climbs,” said David Martinez, Encana’s senior manager for Haynesville development as cited in an article on reuters.com.
Marathon Oil Corp. is using the latest technology of re-fracking on some of their older wells in the Bakken to increase output. Lance Robertson, Marathon Oil’s vice president of North American production operations, said during an interview that when horizontal drilling was beginning to take off in the Bakken in 2007 and 2008 “(well) completion technology was quite different than it is today.” Robertson went on to say that some earlier Bakken wells were readied for production by using a single frack stage, or a single section that creates multiple fissures in rock, and about half a million pounds of sand. Now companies use an average of 30 to 35 stages and as much as 6 million pounds of sand per well. So far, Marathon Oil’s re-fracked wells have exceeded their expectations. Executives of Marathon Oil claim that approximately 100 of their Bakken wells are good candidates for re-fracturing.
fracking has been the center of debate since its beginning. According to Ceres, a nonprofit group that tracks environmental records of publicly traded companies, the water demand for hydraulic fracturing is forecasted to double by 2015. Andrew Logan, director of the oil and gas program at Ceres states, “This has the potential to severely stress water supplies beyond even currently strained levels.”
“Given projected sharp increases” in the production of oil and gas by fracking, a report from the group Ceres said, “and the intense nature of local water demands, competition and conflicts over water should be a growing concern for companies, policy makers and investors.”
Zachary Cikanek, a spokesman for the American Petroleum Institute in Washington states, “Hydraulic fracturing is a safe, proven technology that has been used for over 60 years to increase production of oil and natural gas – changing America’s energy trajectory from scarcity to abundance.”
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