Hundreds of millions of years ago, shale, which are fine grained sedimentary rocks, immersed at the bottom of ancient seas, became organic-rich mud…Heat and pressure transformed the mud into shale and organic matter into gas. Huge quantities of gas are locked in the hard dense rocks below the earth’s surface. Shale gas is typically methane but may contain small quantities of other gases including hydrogen sulphide, carbon dioxide, nitrogen and other hydrocarbons. The composition is dependent on the geological formation as well as the temperature and pressure that the formation has been subjected to over time.
The technique of hydraulic fracturing has been known since the 1940’s, but entered its modern phase in the 1990’s, this because steerable drill-bit motors and electronic telemetering systems allowed developers to exploit previously inaccessible deposits of shale gas.
“Fracking is the process of drilling down into the earth before a high-pressure water mixture is directed at the rock to release the gas inside. Water, sand and chemicals are injected into the rock at high pressure which allows the gas to flow out to the head of the well. The process is carried out vertically or, more commonly by drilling horizontally to the rock layer. The process can create new pathways to release gas or can be used to extend existing channels” http://www.bbc.co.uk/.
It is called Fracking, which is shorthand for hydraulic fracturing and refers to how the rock is fractured apart by the high pressure mixture. Experts also refer to a “frac job” and a “frac unit”.
In the United Kingdom shale gas extraction is still at an early exploratory stage, with limited drilling having actually occurred. Fracturing operations at one site caused minor earth tremors. Shale gas extraction has raised concerns with the general public. Research from the United States, and other countries, suggest that drilling and extraction of shale gas using hydraulic fracturing, could potentially adversely impact on the environment and human health.
In a speech that leaves the American people in no doubt about how there president feels about fracking, president Obama, states that “For the first time in 18 years, America is poised to produce more of our own oil than we buy from other nations. And today, we produce more natural gas than anybody else. So we’re producing energy. And these advances have grown our economy, they’ve created new jobs, they can’t be shipped overseas—and by the way, they’ve also helped drive our carbon pollution to its lowest levels in nearly 20 years. Since 2006, no country on Earth has reduced its total carbon pollution by as much as the United States of America.” http://www.energyfromshale.org/.
The benefits of shale gas are undisputed
The benefits of shale gas are undisputed, shale gas has the potential to be widely a distributed resource that can be relatively cheaply produced and may lessen dependence on imported oil and gas. However, it is still up for debate. In the US for example public concern about shale gas extraction has grown as production has increased and falls into five areas
- Pollution of drinking water supplies
- Air pollution
- Community disruption during shale gas production
- Supply and safe storage of chemicals used in hydraulic fracturing
- Cumulative adverse impact on communities
Similar concerns have been raised in this country pre drilling. It remains to be seen if Fracking will become a source of energy that will become significant for the UK.