South Africa: A Geologist's Take
posted on
Dec 08, 2012 09:17PM
Developing large acreage positions of unconventional and conventional oil and gas resources
Jim Jones
Despite the anti chorus, a geologist argues the environmental and economic cases for exploiting SA’s shale gas resources
Are you worried that if oil companies are allowed to drill for gas in the Karoo, the country and its environment will be headed to perdition? It wouldn’t be surprising, given the traction gained by the arguments disparate environmental and self-interest groups.
But there is another side to the story, a side taking a broader view of the entire country’s welfare. Personally, I wonder what it is about many geologists that makes one instinctively give credence to what they say? Perhaps it’s the fact that their job is to interpret rocks or formations that may be hidden but can’t be changed. There’s no room for exaggeration.
So when Dutch geologist Jan Willem Eggink talks quietly about his company’s hopes for gas exploration I, for one, instinctively believe what he says. Eggink is oil company Shell’s general manager “upstream” here in South Africa. Of course there’s always the danger of my being labelled a Shell poodle by opponents who oppose what Shell wants to do – but that’ something that goes with journalism’s territory.
For those who may not be au fait with oil industry jargon, “downstream” is the part of the business that involves selling oil products - businesses like filling stations – while “upstream” is the fundamental part engaged in finding oil and gas and getting it out of the ground.’
Let’s start with some of the basics. South Africa has no major oil endowment – at least it hasn’t been able to prove one on-shore. But geological models by the US Energy Information Agency indicate that at some 1000 to 2000 metres deep, Karoo shales contain 485 trillion cubic feet of natural gas. That’s an enormous amount – about a quarter the size of the world’s single largest conventional gas resource, the South Pars/North Dome field that stretches beneath the Persian Gulf between Qatar and Iran.
Even if the Karoo were to contain only a fifth of the American estimate, it would still be as large as the massive Groningen field in Holland that has provided more than that country’s gas needs since 1969 and still has a good few decades to go.
On these sorts of figures, the government would be economically remiss if it were to turn its back on the Karoo potential. Looked at from another angle, gas is far cleaner and creates less of the global-warming gas, carbon dioxide, and general atmospheric pollution than coal, the current basis of 90% of Eskom’s electricity. And we might add the dramatic effect shale gas is having on America’s energy security and on bringing down power prices in the world’s largest economy.
Here in South Africa over these past few years, Shell has come under flak from well-organised and well-heeled opponents of its proposals to explore for gas in the Karoo. Understandably, there are concerns over the impact of any new venture on environmentally fragile areas like the Karoo, a vast semi-arid area home to sheep farms and scattered with the fenced-off strictly-private game reserves of the odd billionaire.
With the lifting of a 14-month official moratorium on licence applications, Shell and the others are applying for exploration licences over about 90000km² stretching from Sutherland in the west to Queenstown in the east. Which is where misunderstandings might start. The area isn’t about to be smothered with pipes and gas wells.
Any exploration (or production) licences awarded will come with strict environmental conditions and include exclusion zones around places like Sutherland and its astronomical telescope to the south, around the Square Kilometre Array (SKA) radio telescopes to the north and around towns such as Beaufort West or Graaff-Reinet.
Gas trapped in shales cannot be released automatically like that in conventional oil or gas wells. The release techniques are well developed using what’s known as hydraulic fracturing or “fracking”. That involves drilling into the shale geological formations and using high-pressure water with some acid and chemical additives to create small fractures in the shale through which gas can migrate to a “well” that carries the released gas to surface.
Shell wants to drill between six and 20 exploratory holes over eight or so years to prove the viability or otherwise of the Karoo gas. Each of those holes will need a total of a million litres of water. A producing well would need a lifetime total of 10 million litres. Shock, horror! Water in the semi-arid Karoo! It sounds a lot.
Let’s get some perspective. A million litres is about the amount contained in an Olympic-size swimming pool. Another angle? Eskom uses 600000 litres each day at its power stations. And the gas drillers can probably use the saline or brack water that lies deep under the Karoo’s sheep farms and cannot be used for irrigation or watering animals.
But won’t gas wells pollute the Karoo’s clean underground aquifers as fracking opponents warn darkly? “No” is a reasoned answer. The potable aquifers lie 50m or so below the surface. The shale horizons are more than 20 times deeper, with impermeable rocks in between.
Each test or producing well will need to be lined with impermeable cement as far down as the shale beds. So gas can’t escape into intervening geological beds. More to the point, this gas isn’t being pumped out of the ground under great pressure. It moves to the surface because well-head pressures are lower than those slightly higher ones occurring naturally at depth.
There’s only ever been one verified example of water pollution and that was in the US in an area where the gas shales were only a hundred or so metres deeper than the aquifers.
Sure there will be drill rigs and eventually, if gas is found, well-head equipment and pipelines. But they are widely scattered, kilometres apart, and comparatively small. If the whole lot were put in one place they’d cover an area the size of 60 football pitches, Eggink reckons. And that scattered through the vastness of the Karoo!
It’s worth pointing out that one borehole from the surface can access large areas underground. Drill steels can be bent in almost any direction and over large distances underground so one surface collection point can serve dozens of underground “wells”.
Of course, if vast amounts of gas were to be found, the national infrastructure needed to exploit it and transport it to where it can be used wouldn’t appear as if by magic overnight. Eggink suggests the infrastructure already in place to handle the off-shore gas near Mossel Bay be carefully extended – it needs to be extended, in any case, to handle the LNG (liquefied natural gas) that we are increasingly importing. Might as well start sooner rather than later.
And we should be working on planning plants at, say, Coega, convert gas to petrol or diesel as Sasol is doing in Qatar and is planning in Louisiana.
The fact is that, along with the rest of the world, South Africa isn’t going to escape the use of fossil fuel for its energy and transport needs any time soon. Our absolute if not our relative dependence on coal will continue – we’re not likely to be using less each year for decades to come.
Yes, there are the renewables extolled by environmentalists. But their footprints are not minor. Solar voltaic farms can be concentrated over tens and tens if not hundreds of square kilometres. And wind farms are the same. Few people want them in their own back yards. Nor do they want to be near nuclear power stations.
So we are back to gas to underpin our energy future. Isn’t it time we moved on beyond the emotionalism of environmental arguments to cooler debate?