This low-impact process includes three basic steps.
First, a field technician uses a hand tool to make a small, shallow hole in the ground. The hole measures from 1-2 cm in diameter and is 50-100 cm deep. The coordinates are recorded using GPS hand units.
Second, a flexible tube is placed into the hole. This tube captures the hydrocarbon gases that naturally seep to the surface.
Finally, the entire tube is retrieved three weeks later and the hole is filled.
This puzzles me. How do those hydrocarbons travel all the way up to the surface if there are thousands of feet of impervious rock and NO VERTICAL FRACTURES? Why is it they say toxic water can't travel back to the surface? Some believe they know there ARE vertical fractures that reach to the surface. Shell Oil also admits this in it's article Sniffing for Gas. Another article I found was from the Colorado School of the Mines. In this article, the author talks about hydrocarbons making it to the surface vertically. All viable methods of surface geochemistry depend on mechanisms of loss from the reservoir and vertical migration, without frequent lateral offset or dispersion.
If this migration is occuring, how can they say water contamination from hydraulic fracturing chemicals is impossible? FRACKING CAUSES FURTHER ROCK FRACTURES, and the toxic chemicals are meant to prop open the rock.
Surely you can't have it both ways.