by Peter Hardy; 28 November 2012
The phenomenon of shale gas is both topical and controversial. Its proponents claim that it is a clean, environmentally friendly and abundant source of cheap natural gas; its opponents believe the opposite. In various countries it is a fast growing industry and operations have begun in the UK.
With conventional reserves of natural gas being quickly depleted, gas prospecting is
turning to “unconventional resources”, one example being gas found in shale.
Uncommon technologies, notably hydraulic fracturing and horizontal drilling, are
necessary for shale extraction to be economical.
Shale Gas has faced some difficulties over concerns regarding environmental pollution. In the US, an influential film was released alleging that waste fluid from hydraulic fracturing,
“flowback water”, was polluting groundwater. While it is possible for methane to enter
groundwater through a faulty well completion, The Institution of Gas engineers and Managers,IGEM, is satisfied that Environment Agency and HSE policy is adequate to prevent risks to the environment or human health and recommends that if flowback water is to be held temporarily in open pits, an adequate overspill system be in place.
There have also been two earthquakes in Lancashire thought to have been caused by
shale gas operations. Furthermore, the cause of a magnitude 4.7 earthquake in Arkansas
near to where waste water was injected into a shale gas well has not been fully
determined. The results of an investigation into the Lancashire earthquakes have been accepted as being the results of fracking operations and new guidelines are already being proposed to alleviate the risk of this happening again. IGEM recommends that seismic activity near hydraulic fracturing operations be monitored and that the suitability of reinjection for disposal of water be investigated.
IGEM has identified a need for standards in this country pertaining to shale gas and its
extraction processes and is working with the industry and Government Agencies to provide a guidance document for onshore fracking in the UK.
With the lack of public information and sometimes animosity towards shale gas, drillers
need to consider developing corporate social responsibility programs tailored to the
needs of the communities local to drilling, with especial consideration towards
Worldwide, shale gas has had a significant and growing impact on gas production
and looks likely to rapidly transform the energy situation. The estimated recoverable shale gas reserves worldwide are in the region of 6,622 trillion cu feet with China having the largest reserves of 1,275 trillion cu feet followed by the US with 862 trillion cu feet.
This is against the backdrop of worldwide annual consumption of 106.7 trillion cu feet. From known shale gas reserves alone this equates to 60 years of gas usage based on the current level of consumption. The development of the US shale gas industry over the last 10 years has resulted in the price of gas falling from $12 per million British thermal units (BTUs) to $3.8 per million BTUs.
This is against the background of worldwide reserves of conventional reserves of Natural gas of 6,609 trillion cu feet. Over half of these reserves are in Russia, Iran, Turkmenistan and Qatar.
In Europe, Poland and France have the largest reserves; Poland has embraced the industry and is looking forward to its shale gas reserves ending dependence on Russian gas. France, on the other hand, has outlawed the hydraulic fracturing technology vital to shale gas on environmental grounds.
The UK’s shale gas reserves are unlikely to be large enough to be a “game changer” however they would contribute to gas security and the UK’s energy mix, as well as being a lower carbon alternative to coal-fired electricity generation. The estimates of recoverable gas in the Bowland shales in Lancashire are 2 trillion cu feet with the existing UK gas usage of 90 billion cu feet per annum. This means that the Lancashire reserves alone could represent 20 years of UK gas supply. There have been other sites of possible shale gas already identified in South Wales, Scotland and the Peak district.
As well as conventional gas reserves and shale gas reserves already identified the above figures do not take into account other areas of unconventional gases such as coal bed methane and tight sands and there are already known reserves of 4,000 trillion cu feet in America and China with further large deposits in Russia, Australia, South Africa, Canada and India but these have yet to be accurately quantified. Australia is already looking to exploit its reserves of these gases in the next 2-3 years.
There are already substantial reserves of gas available worldwide, however the development of these unconventional gases, which are often in more politically stable parts of the world, will provide an ongoing security of supply to the Western World going forward.
Peter Hardy is Technical Manager at The Institution of Gas Engineers and Managers