|Photograph by Stuart, in Brackenridge Park, TX|
The Eagle Ford Shale gets its name from a town west of Dallas so called due to the shale outcrops that can be seen. the deposit is about 250 feet in thickness and is said to reach depths of 12000 feet and consisting of organic matter rich in marine fossil shale. So its very rich in oil and gas and it has had an impact on the financial landscape as well as the physical landscape and extends all the way South to Laredo in a 50 km wide width.
Oil and gas has changed the fortunes of many struggling cattle ranch owners. South Texas has been the victim of many droughts and over the years some of these large ranches have been subdivided or "cut up" into smaller ranches and farms and sold off to save the land owner from foreclosure. Texans have been experiencing severe drought even as recently as 2011. In fact when we arrived here in September 2011, the ground was a dry, brown to grey sun scorched colour (Americans read color) with little to no grazing grass. It was hot with temperatures at 115 degrees Fahrenheit.
So going back to the oil and gas in the Eagle Ford Shale play as it is commonly known, has changed the fortunes of Texans and provided plenty of jobs for Americans and Mexicans.
This photo was taken 500 yards from our house.
The oil and gas is harnessed deep below the earths surface by the process of "hydraulic fracturing" known as "fracking" and is made possible since the shale is made up of a brittle carbon layer.
"Fracking" is a process of drilling a well and pumping a highly pressurised fluid into the well which ultimately cracks the the sub soil and creates channels and this allows the trapped oil or gas to pool into an area and is easily harnessed. This process has been around for a long time but now has been further developed to where a well operator can drill horizontally underground to maximise the effect of the "fracking" technique and increasing the potential of a well. The fluid or proppant that is pumped into the well can be made up of different substances and is applied in the form of gel or foam but the most common is probably "slickwater" made up of 99% of water and 1% additive. The additive could be hydrochloric acid which helps to break down or dissolve certain rocks like limestone.
With one exception the use of "fracking" fluids for hydraulic fracturing was excluded from regulation from the American clean water act in 2005.