Fracking qualifies for aged pension

Over on the About Geology Blog, Andrew Alden shows us that yesterday was the 65th anniversary of Hydraulic Fracturing (Fracking/Fraccing). I was quite surprised to learn that this “unconventional” technique was developed in my grandparent’s generation. In his blog post Andrew points out some of the controversies in the United States about “Fracking” and provides his opinion on the practice. I don’t want provide to provide any opinion here about the Australian situation, just to outline a very quick summary of how it is used.

Having said the above, I think it is important to mention that there is some differences in experience between Australia and the United States. The main difference being that any chemicals used in “Fracking” must be fully disclosed (unlike the USA where they are much more secretive). Another difference is that in the USA “Fracking” is most commonly used in “Shale Gas” formations where it has been reportedly been linked to many problems with regard to aquifer cross-connection and contamination. Coal Seam Gas in the USA are also a situation where Fracking is frequently used, though this has very few of the same issues of Shale Gas fracking (Blackam 2014).

In Australia “Fracking” is frequently used in “Tight Gas” situations where directional drilling alone is impractical. This practice is especially common in the Moomba Gas Fields of Queensland and South Australia now this field has become depleted in the easily accessible “Conventional” gas. Hydraulic fracturing is also sometimes used in Coal Seam Gas situations. In the Northern Rivers I understand there has only been one case of hydraulic fracturing which was used in a “tight” situation.

This is by no-means a clear bill of health for unrestricted use of the practice of Fracking. Many questions still remain about what damage the practice can cause (e.g. Batley & Kookana 2012).

I’ve done some posts on the different natural gas sources and summarised them on this page. Until I actually do a blog post on what hydraulic fracturing actually is, I recommend this summary from the CSIRO. Alternatively, this CSIRO/Industry publication, though developed in partnership with the gas industry is actually even more detailed and very good.

References/Bibliography:

*Batley, G.E. & Kookana, R.S. 2012. Environmental issues associated with coal seam gas recovery: managing the fracking boom. Environmental Chemistry. vol9 p425-428
*Blackam, M. 2014. Source, Fate and Water-Energy Intensity in the Coal Seam Gas and Shale Gas Sector: An Exploration of the relationship between energy and water in the unconventional gas sector. Water, Journal of the Australian Water Association. vol41 No.1 p51-56

Armidale submerged

Armidale is well known for its height above sea level, with some areas above 1000m it is at a relatively high altitude by Australian standards. The city is located in the New England, ‘Northern Tablelands’ which provides an indication of the landscape in which it is situated. The area resembles a very large plateau with comparatively light rolling hills compared with the nearby escarpment and edges of the tablelands. In fact, Armidale is just a tiny bit to the east of the crest of the Great Dividing Range. Surprisingly, this area was in part inundated by a lake, or lakes.

Examples of some rocks that make up the Armidale beds
The big sample at the front has been partially turned into silcrete.

One of the headwaters of the Macleay River, Dumaresq Creek flows through Armidale. In places this creek, as well as other creeks in the area, have cut through the basalt rock that covered the area. A description of this process was covered in an earlier post. In this post I’d like to describe the sediments that lie under the basalt. These are Eocene (or earlier) sediments named by Voisey (1942) the Armidale Series, now known as the Armidale beds.

The Armidale beds are comprised of fluvial (river) and lacustrine (lake) deposited sediments. These are principally conglomerates, siltstones, sandstones and shale. Interestingly, the shales are laminated possibly as a result of seasonal deposition in a lake. They also contain abundant plant fossils. The material that makes up the sediments is particularly obvious in the conglomerate. The conglomerate clasts are derived from the older underlying geology, for example clasts of jasper, quartzite and granites.

The Armidale beds occur in small remnant areas (the balance of the beds having been eroded away). These remnants occur throughout the Armidale area but almost as far away as Wollomombi to the west, near Dangars Falls to the south-east and Kellys Plains to the south-west. Voisey 1942 named this area Armidale Lake which is a palaeo-lake that only exists now in the sediments that it left. The formation of Armidale Lake occurred either before or during the volcanism that ended up covering a majority of the Armidale region in blankets of basalt lava (lavas of the Central Volcanic Province). In fact, the Armidale beds were preserved by this blanket of basalt both directly and through metamorphism beds in the area of contact. This metamorphism of the Armidale beds created a layer of hard silcrete (once known as greybilly) which itself was resistant to erosion and helped preserve the underlying un-silcretized sediment from being washed away.

The picture above is an example of the Armidale Beds that occur near the Armidale garbage disposal centre. A very accessible example is located on Madgwick Drive on the way to the University. It is actually one of the best remaining exposures of the unit and has been used for years by local schools and the university. Indeed, Banaghan & Packham 2000 have the road cutting as a stop on their Armidale-Yarowych geological tour.

References/bibliography:

*Branagan,, D.F. & Packham, G.H. 2000. Field Geology of New South Wales. Department of Mineral Resources.

*Fitzpatrick, K.R. 1979 The Armidale area. Geological Survey of New South Wales. Geological Excursion Handbook 1

*Voisey, A.H. 1938. The Geology of the Armidale District. Proceedings of the Linnean Society of New South Wales.

*Voisey, A.H. 1942. The Geology of the County of Sandon, NSW. Proceedings of the Linnean Society of New South Wales. V67.

An Australian and Indonesian Geological Relationship

Australia got its most recent reminder about the power of volcanoes only a couple of weeks ago. Mount Kelud (or Kelut) erupted on the populous island of Java in the Indonesian Archipelago. The resulting ash cloud has caused immense problems for people travelling to Asia or even Europe. The Darwin Volcanic Ash Advisory Centre (Darwin VAAC) advised that aircraft travelling on many of the popular Indonesian (particularly Bali), South and East Asian routes, would be in great danger of having engines failing. Therefore many flights were grounded.

The Darwin VAAC is responsible for Volcanic Ash advice covering the Indian sub-continent and South East Asia (The most concentrated number of active volcanoes in the world). Very few people realise the essential role that Australia plays in understanding the way volcanic ash behaves in such an active region. This is despite Australia has only a few isolated or insignificant volcanoes itself. Like the role of the VAAC, Australians don’t realise just how significant volcanism is to our second nearest neighbour (or indeed our nearest one, Papua New Guinea).

Readers of my blog will be aware that I focus almost entirely on the geology of the Northern Rivers, Eastern New England Tablelands and Mid North Coast areas of the state. Regular readers will also be aware that on occasion I indulge myself with a discussion or some opinions on geological matters elsewhere. Indonesia is just too important from a geological perspective to ignore. Having Indonesia come to our attention only when immigrants on boats are reported, volcanoes affect plane flights to Bali or the name Chapelle Corby is mentioned misses how much we are involved in and how much more we should be involved in managing volcanic hazards in our region. Including supporting Indonesia in its efforts to keep people safe.

Here are some selected facts about dangerous volcanoes:

• Volcanic eruptions can be compared by a logarithmic scale called the Volcanic Explosive Index (VEI). 
• VEI 0 are small explosive eruptions, VEI 8 are huge catastrophic eruptions. 
• All recorded eruptions of VEI 6 or greater has killed someone. 
• Approximately 50% of recorded eruptions of VEI 4-5 have killed someone. 
• The majority of deadly volcanoes (VEI 6 or less) claim about 80% of their victims between 7 and 10 kilometers from the eruption. 
• Lava causes only 0.34%-0.79% of deaths from eruptions. 
• Pyroclastic flows cause between 33-46% of deaths from eruptions. 

Here are some selected facts about Indonesian volcanoes:

• Monitoring the effect of volcanic ash in Indonesia is the responsibility of the Australian Bureau of Meteorology (via the Darwin VAAC). 
• On average for every volcano that erupts in Indonesia, 27 people will die.
• Five volcanoes have has significant (and recurring) eruptions already this year (Jan-Feb 2014). Those are Sinabung, Saiu Island, Kukano, Raung and Kelut. 
• The largest explosive eruption known occurred at Toba about 30 000 years ago. 
• In 1815 Mount Tambora erupted killing approximately 60 000 people and led to the “year without a summer” in Europe. 
• In 1883 Krakatoa erupted with the resulting in approximately 36 000 deaths, the sound of the eruption was reportedly heard in many parts of Australia. 
• Approximately 76 different volcanoes have erupted in Indonesia in the last ~500 years. Most of these erupting frequently. 

Here is an example of what people are trying to do about the dangers of volcanoes in Indonesia: http://citiesonvolcanoes8.com/. This is a geology related conference that people in Australia probably never hear about.

More information on the Darwin VAAC can be found here.

References/bibliography:
*Auker, M. R., Sparks, R.S.J., Siebert, L., Crosweller, H.S. & Ewart, J. 2013. A statistical analysis of the global historical fatalities record. Journal of Applied Volcanology 2:2
*Smithsonian Institution. Smithsonian Institution / USGS Weekly Volcanic Activity Reports (All editions January-February 2014)

What is CSG?

What is CSG? Very simply Coal Seam Gas (CSG) is natural gas obtained directly from coal seams. Another common name for CSG is Coal Bed Methane (CBM). Like most natural gases, the chemical components of CSG are dominated by methane. Though some higher end hydrocarbons such as ethane or propane may also be present.  Carbon dioxide and nitrogen are usually significant components of CSG too and the higher the proportion of these non-hydrocarbon gases the lower the quality of the gas. This simple summary does not tell us very much, so more detail is required.

CSG is an interesting gas when compared to ‘conventional’ gases. ‘Conventional’ gas has migrated away from coal and organic rich sedimentary rocks into other porous rocks. The gas is then held in place by impermeable layers. What makes CSG different is that the gas has only migrated very small distances (if at all) to natural pore spaces such as fractures (cleats) in the coal layers. These pore spaces usually contain natural water that was left in the coal when it was laid down or water that subsequently migrated into the coal seam. The water associated with the coal seam is very important because it is actually the pressure of the water in the coal seam that keeps the gas in place. It is the hydrostatic pressure that keeps the gas in place.

In open cut or underground coal mining, CSG is a curse. It is considered a waste product and an explosion hazard. It is therefore vented as much as possible to make the coal mines safe to work in. The recent Pike River Mine explosion in New Zealand is an example where the failure to vent enough CSG caused a tragedy. As water is removed from coal mines the chances for gas mobilisation increases due to the above mentioned effect of hydrostatic pressure. This further increases the risk of explosion in coal mines.

Idealised relationship between CSG and water production

Natural gas became more popular for domestic and industrial use over the last few decades and the means to transport it economically became available (e.g. LNG). This meant gas that was often a by-product of the oil and coal industries became important in its own right. This led to people searching for gas sources in their own right, CSG included. Petroleum engineers realised if you reduce the pressure of water in a coal seam and collected the gas you could actually use the gas as a resource leaving the coal in place. This means that drill holes can be placed into coal seams and the water drawn out. The water drawn out (called formation water) is actually a ‘by-product’ of the gas extraction process. The formation water is the nuisance that needs to be removed to allow the gas to escape. This means that a new gas well will produce very little gas at first and lots of ‘waste’ water. As the water is drawn down the gas production increases and the water production decreases. Interestingly this is the opposite of that which occurs for ‘conventional’ gas, where waste water is a problem in the later stages of production but not early on.

Many people are concerned about CSG in Australia, particularly in our northern rivers region. This concern is driven by the possible effect of CSG extraction on beneficial groundwater. The use of techniques such as hydraulic fracturing that may be used to increase or prolong gas production is also raised as a concern. To keep this post short I will cover both of these issues in future. However, I will suffice to say that there is evidence that groundwater can be affected during CSG extraction despite producers trying not to have any impact. These are particularly noted in certain geological formations. There are also situations where there is no impact on important aquifers too. This matter is clearly quite complex and a one size fits all understanding does not apply very well. Hopefully, my future posts will tease the details out a little bit more.

The Road to The Gorge

Note that since this post was written the Towgon Grange Granodiorite has been renamed the Towgon Grange Tonalite.

Many people in the region know about “The Gorge”. It is a remote, yet popular area on the Clarence River. The road to The Gorge is interesting because of the change in geology that is experienced. The main route to The Gorge is via Grafton and Copmanhurst. By travelling west from Copmanhurst along the Clarence Way you move from the sedimentary rocks of the Clarence-Moreton Basin. First,  the rugged cliffs made from the Kangaroo Creek Sandstone give way to the rolling hills of the Walloon Coal Measures then Koukandowie Formation. Some road cuttings show weathered examples of these rocks. Turning off the Clarence Way and passing over the camping ground, swimming hole and bridge at Lilydale leads you to The Gorge turn-off. The Lilydale and Newbold areas have some of the oldest rocks of the Clarence-Moreton particularly the Laytons Range Conglomerate. But on the day I was there, I was not so interested in those rocks… because I was getting into the New England Orogen.

It is rare opportunity for me to explore the foot hills of the New England region. I love the feeling of the place, the wonderful landscape, climate, history and even culture. The place just seems to have a feeling of connection with the people who live there. Luckily, I managed to visit the edges of the New England escarpment for a little while on the weekend. While there I managed to experience more of the rocks that are the foundations of the landscape of New England.

Towgon Grange Tonalite - on The Grange Road, Middle Clarence River area

Driving along The Gorge road the rocks of the Silverwood Group are passed by. These are slightly enigmatic rocks of the New England Orogen, interpreted as subduction complex rocks (Van Noord 1999). Mainly outcropping in streams the rock of the Silverwood Group in this area are none the less quite hard and old metamorphosed marine sedimentary and volcanic rocks. The Silverwood Group is interesting because it also occurs near Texas in Southern Queensland and it is only partially understood in our region. But more about the Silverwood Group in a future post. 

Round tors appear by the road side near Table Creek about 15km south of The Gorge. These tors are a classical shape formed by the weathering and erosion of granite type rocks. Here are rocks that make up part of the New England Batholith. The batholith is numerous masses of intrusive igneous rocks plutons that were molten well before Australia was separate from Gondwana. The ‘granite’ here is called the Towgon Grange Granodiorite. Like the Dumbudgery Creek Granodiorite that occurs about 20-30km further north the pluton is bisected by the path of the Clarence River. This helps to illustrate the unusual behaviour of the Clarence river as it travels backward and forward over soft and hard rocks. In fact the other side of the pluton can be easily found on the other side of the river just off the Clarence Way.

The Towgon Grange Granodiorite intrudes into the Silverwood Group meta-sediments. The rock sample at Table Creek (pictured) is actually not a granodiorite. It is notionally similar in appearance but contains much less potassium-feldspar. The main minerals are light coloured plagioclase feldspar, quartz and darker clinopyroxene and amphibole. The rock sample shows that much of the clinopyroxene is mantled (surrounded) by amphibole. The lack of potassium-feldspar means that this particular sample is probably a Tonalite according to the most popular rock classification (QAPF). In fact Bryant et al (1997) actually notes that the Towgon Grange Granodiorite only contains small amounts of Granodiorite, with most being Tonalite or Quartz Diorite. This is a good example how stratigraphic names may be misleading to first time geologists!

Bryant et al (1997) classifies the Towgon Grange Granodiorite as an I-type granite of the Clarence River Supersuite. This means that the Towgon Grange Granodiorite is derived from the melting of other igneous rocks. The Towgon Grange Granodiorite is also comparatively low on silica (quartz) in comparison to other Clarence-River suite intrusions. It still contains enough quartz that it is generally visible in hand specimens. The age of the Towgon Grange Granodiorite is about 248-249Ma old. The younger sedimentary rocks of the Clarence-Moreton Basin overlie parts of the Towgon Grange Granodiorite and Silverwood Group.

The Towgon Grange Granodiorite is one of those rocks that just about no one in the general public has heard of. But, it is a good example of rocks that illustrate many points about the landscape evolution of the New England Orogen and the Clarence River. It occurs in a scenic area and is also a very attractive rock in its own right.

References/bibliography: 
*Bryan, C.J., Arculus, R.J. & Chappell, B.W. 1997. Clarence River Supersuite: 250Ma Cordilleran Tonalitic I-Type Intrusions in Eastern Australia. Journal of Petrology V.38 No. 8.

*van Noord, K.A.A. 1999. Basin development, geological evolution and tectonic setting of the Silverwood Group IN Flood, P. G. (ed.) Regional Geology Tectonics and Metallogenesis: New England Orogen - NEO '99 Conference University of New England.

List of Natural Gas Posts

To try and bring some order to some subjects that have been dealt with in previous posts I think it would be useful to create some list posts. This first list is about a subject that is very topical at the moment, natural gas. Natural gas includes so called "unconventional" gas such as coal seam gas (CSG), shale gas, tight gas.

Posts on "conventional" gas

• Being tight with loose terminology?

Posts on coal seam gas

• Baseline CSG methane in groundwater
• Clarence-Moreton Basin CSG Bioregional Assessment
• What is CSG?
• Some musings on coal seam methane
• Coal seam gas gets a seismic thump!
• Why you wont find CSG here

Posts on shale gas

• Gas from Shale

Posts on tight gas

• Being tight with loose terminology?

Posts on other unconventional gas

• Fracking qualifies for aged pension
• Deeply a fire smoulders

Our Clarence-Moreton Basin and Middle-Earth

Over at the European Geophysical Union Blog Between a Rock and Hard Place there is a very interesting post. It seems that a researcher from the University of Bristol has released a paper comparing the climate of Earth with that of Middle-Earth (As in Lord of the Rings and the Hobbit). Yes, you read that right!

The climate model the researcher (Dr Lunt) created seems to demonstrate that the climate of Middle-Earth is best represented by the climate that we experienced in the Triassic period. That means that the Middle-Earth's climate was similar to ours while the rocks of the early Clarence-Moreton (and Ipswich) basin were being laid down. That is the time that the rocks of Evans Head, Nymboida, Chillingham and others were being formed.

For those that are interested in Tolkien's world here is a link to the paper (in English). For those obsessed with Tolkien's world here are links to the paper in Elvish and Dwarven Runic. I love the conclusions including the observation that "Mordor would have had an inhospitable climate, even ignoring the effects of Sauron"