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There’s more to coal seam gas than Gasland

There’s more to natural gas than Gasland. lilicomanche/flickr

Senator Christine Milne has declared coal seam gas to be “a disaster for Australia,” and there’s much concern in the community about its effect on the environment.

Some of this concern stems from horror stories from the United States, in particular the documentary Gasland, in which farmers’ water could be set on fire due to the gas drilling on their properties.

But before the alarm bells start ringing, it’s important to understand the difference between the US and Australian situations.

Gasland dealt with shale gas, but in Australia, we’re dealing with coal seam gas, and there are important differences between the two.

Regardless, both coal seam gas and shale gas could significantly increase Australia’s energy supply and security.

There are benefits from the money spent on exploration, completion, and production directly, as well as the multiplier effects that will reach throughout the economy (thousands of skilled jobs will be created, along with royalties and tax revenues from both direct and value added activities within Australia).

There are also environmental benefits. Natural gas fired electricity generation produces roughly 60% less greenhouse gas emissions in the generation of baseload electricity. Peaking power plants will provide a necessary backup to intermittent renewable generation.

It is also possible to dual-fire power plants with natural gas and coal, which reduces emissions significantly relative to a coal-only plant.

Coal seam gas (CSG) (also known as coal bed methane or CBM in the USA) and shale gas differ both in terms of the nature of the geology in which it is found and in the processes employed to extract it.

The end product of each process, however, is the same: they produce methane, which is the cleanest of the fossil fuels that are used to power much of our, and the world’s, electricity generation systems.

It is wrong to relate issues and concerns raised in docudramas like Gasland to the CSG developments underway in Queensland.

Some of the concerns about shale gas development come from the use of a new set of technologies. As we move along the learning curve with these technologies, the likelihood of environment problems associated with the shale gas operations is significantly reduced.

CSG is gas (mostly pure methane; natural gas) captured in coal seams deep underground. Releasing it requires removing substantial amounts of water also naturally contained within the coal seams.

This dewatering process raises the water management issues peculiar to CSG operations.

Shale gas operations, on the other hand, involve a process known as hydraulic fracturing, also referred to as fraccing (and sometimes fracking).

The term shale gas is also very descriptive of how the natural gas/methane is “held” below ground. Conventional natural gas is captured underground in geological structures, like sandstone, with an overarching impermeable rock barrier.

This gas may be accessed by drilling wells down through the cap-rock to access the gas captured within the “granules” and “pore spaces” of the reservoir rock.

Shale gas is extracted with two technologies: horizontal drilling (or more generally directional drilling), whereby the operator initially drills straight down two to four kilometers below the surface.

Once the target shale is reached the drill bit is turned to follow the shale formation horizontally. These horizontal sections may run to 3.5 – 4 kilometers from the initial vertical segment. Shale formations may run for hundreds of kilometres or more.

The drill hole is then cased with steel pipe, which is perforated so that hydraulic fluids can reach into the shale and create fractures, which will then allow the gas to flow at a faster rate.

The fraccing operation pumps fluid into the shale formation under high pressure. This fractures the shale rock to open the too-tight “granules” and pores of the shales.

Any time we drill down into the earth in search of resources below, we potentially pass through groundwater.

This happens in all drilling operations. Sometimes operators may fail to follow the proper procedures, and fluids and gases may enter the groundwater. We know how to prevent this.

The second issue has to do with the fraccing process itself, and the nature of fluids employed. If too much pressure is employed, or if the geological stresses are not fully understood, or if the shale formation is relatively shallow and near a groundwater source, a fracture can extend into the groundwater formation, and there could then be mixing of fluids and gas into the groundwater.

Given that most of the shale gas formations are relatively deep and well below groundwater formations, this negative outcome is relatively unlikely. The industry has learned far more about how to control the extent and direction of the fractures created.

Hundreds, if not thousands, of chemicals are included in the fluids injected. But it is frequently ignored that these chemicals typically make up less than 3% of the fluids injected.

The particular mix of water, sand (which is included to help hold the fractures open once the fluid is withdrawn from the well), and chemicals is designed to enhance the flow of natural gas from the well.

If the appropriate procedures are followed by the operator, none of these chemicals should find their way into the groundwater.

Basically, it is these two issues related to shale gas that Gasland and other media coverage have attempted to address, and neither of these is relevant to CSG. There will be no flaming water taps or chemicals in the groundwater as a consequence of CSG production.

If the proper procedures are followed, the economic and environmental benefits of CSG will likely far outweigh any additional cost associated with such compliance.

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