What Is Re-Fracking?
Re-fracking is an oil company practice of returning to older shale-oil and shale-gas wells, fracked in the recent past, but which are no longer in production. The company hopes to use new, more effective, extraction technologies to revitalize and capitalize on the well's resources. Re-fracking can be useful on those deposits where the shale produces low yields, as it may expand their productivity and extend their lifespan.
Re-fracking, in its most basic form, is shooting a mixture of mud, composed of sand, chemicals, and water into an underperforming well to boost production. Companies have been using this function to some degree for decades. The mixture helps to form cracks in the substrate and hold the cracks open once they develop. The breaks in the rock and soil allow the oil to flow more rapidly, boosting the amount that the company can extract from the formation.
Re-fracking has come to the fore recently as companies are now employing this long-used technique with vertical drilling processes and other technologies. These methods allow a company to access deposits which were previously useless.
To that end, companies are now re-fracking some wells sunk as little as three years ago. One technique in the re-fracking process involves sealing up larger cracks in the well's shale with small plastic balls so that new proppant may find its way into tighter cracks with the help of a higher pressure wellbore.
For example, organizations are re-fracking in the Bakken shale deposit of North Dakota to revisit some wells drilled between 2008 and 2010, due to improved hydraulic fracturing technologies. According to the North Dakota Pipeline Authority, companies have re-fractured more than 140 wells in the Bakken as of mid-2017. Most of the re-fracked wells saw an increase in production as a result. Similarly, companies are re-fracking in other well-established, large shale formations in the U.S. such as Eagle Ford and Barnett, both in Texas.
The Costs of Using Re-Fracking
Oil and gas recovery may cost many millions of dollars to drill and complete, and some have a rather low recovery or production rate. Also, some areas have large sections of deposits that produce either nothing or next to nothing. The appeal of re-fracking is that it can allow new technology to extend the life of existing wells, where exploration and production companies already have found some success. This process limits the amount of fresh ground that must be opened up.
Another advantage of the exploration and production companies using re-fracking is that it often costs less than installing new vertical wells.
As is the case with fracking in general, re-fracking is controversial. Critics point to the same adverse effects it can have on the air, water, and soil of the areas where re-fracking happens. For example, one of the primary chemicals used in the re-fracking or fracking process is methane, which escapes into the atmosphere during extraction. Methane is 25 times stronger than carbon dioxide in trapping heat and causing greenhouse effects. Also, the release of this gas is detrimental to air quality in the vicinity of fracking sites. (For more, see: Fracking Can't Happen Without These Companies) and (Why Schlumberger Is A Name You Should Know.)