Fracking is the new drilling technique that is rapidly changing the global energy situation. It has tipped the U.S. from being the world's largest petroleum importer to China. As I have commented before, that changes the U.S. national security interests in protecting the petroleum supply line to lesser importance. It heightens China's concern about the petroleum supply line.
This strategic change is because the U.S. is drilling down vertically two miles, then drilling another mile horizontally. A charging well is drill in parallel to the collection well and fluids are pumped under pressure into the charging well to coax the hydrocarbons out of the semi-porous rock. The dilemma is that our drinking water aquifers can be contaminated by these fluids pumped down into the charging well.
Fracking: Water Concerns Persist tells that methane and arsenic in drinking water wells are correlated with fracking. Also, methane and ethanol were discovered in the wells which should not have appeared at all. Some of these drinking water wells were contaminated above safety levels for the chemicals.
There are complicating factors that prevent direct linkage to the fracking, but there is a correlation.