Unconventional wells are also more expensive to drill. According to the IHS Global report, a typical shale gas well costs $3 million to $9 million to drill. A conventional land-based oil or gas well costs about $400,000 to drill, according to the Department of Energy. Jackson notes that the decline curves for unconventional wells are steeper than conventional wells, an economic consideration that could lead to environmental concerns.
“The production appears to drop off more quickly in an unconventional well than it does in a conventional one,” Jackson says. “That means you either have to drill more wells to keep the flow up for the same amount of wells, or you have to go in and refrack wells more quickly to boost the flow back up. With refracking, there’s more impact on water use, more wastewater generated, more of the industrial activities that cause friction with people.”
The biggest environmental concern involves the chemicals used in the fracking process. The chemicals employed during fracking serve several purposes — to prevent corrosion of the well casing and limit bacteria growth in the formation, for example. But there are concerns that these chemicals could reach water supplies.
Hydrochloric acid, methanol and sodium hydroxide are among the chemicals commonly used in the process.Page 3 of 6 | Prev Page | Next Page