by rockdoc123 » Mon 23 Jan 2012, 09:04:20
$this->bbcode_second_pass_quote('', 'T')he following testimony is very telling:
Reading through the complaint it seems somewhat confusing. At one point they claim the contamination is coming from an Encana coal bed methane well which is quite shallow and suggest this is verified by ethane isotopes being similar to that collected from their drinking water. Later on they claim that the source of their gas is coming from much deeper in Cretaceous sandstones. Perhaps it is difficult to tell for sure.
There are several things that need to be considered.
If indeed their gas is coming from a shallow zone it could be completely natural coming from the Horseshoe Canyon coals. Gas from coals is bound in the organic lattice and requires that water is produced before the gas can become unbound and is then freely produced. This is exactly how cbm production schemes work...water is produced for a long time before gas can be produced. This is also in keeping with the 8 years of gas free production they have had.
Alternatively if the gas is coming from deeper it could be coming from a natural gas reservoir where by producing the bottom water over a period of 8 years they eventually cones gas down from a high elevation at some distance from the well.
One of the main problems here is that in Alberta as is the case almost everywhere water wells are not required to either be cased and perforated or is the producing horizon required to be registered. As a consequence it is often difficult to be sure what horizon is producing and where any specific contaminants might be coming in.
In the area these folks moved into gas drilling has been a fact of life for decades. Unfortunately home owners hire water drilling companies to drill water wells without hiring geologic consultants who could tell them about possible problematic aquifer levels. Its cheaper of course but fraught with risk. In short you should never try to use a known producing horizon as a acquirer unless you are absolutely sure ther is no gas in that zone for numerous miles away. As well everything but the aquifer you are producingnfrom should be cased and cemented. Unfortunately this is a costly proposition.
This is not something new farmers have noted gas in their water wells as far back as the turn of the twentieth century. One solution is to live with it. Producing into a setting tank which is then vented solves most of the problems.