The greatest risk is that the fracking fluid leaks into the surface water
and shallow aquifers used by people, livestock and the ecosystem,
due to inadequate sealing of the upper parts of the borehole,
or following a spill on the surface. These risks can be reduced,
but not eliminated, by good engineering.
South Africa has been considering shale gas development in the Karoo – an arid part of the country that spans more than 400 000 square kilometres – to add to its energy mix. The possibility of “fracking” in the region has provoked heated debate. The Conversation Africa’s Ozayr Patel asked Robert Scholes and Greg Schreiner to unpack the issues.
What’s happening in terms of shale gas development in South Africa?
The Scientific Assessment for Shale Gas Development in the Central Karoo was published in October 2016. So far no decisions on the current exploration right applications have been made, despite reports to the contrary. If rights are granted, exploration activities could start within the next 3-5 years, conditional on the results of site-specific environmental impact assessments.
If it’s found that gas from deep shale layers can be liberated at commercially viable flow rates, the Karoo could be the location of a domestic gas industry within the next 20 years, lasting for several decades.
The public and the regulators have had lots of questions about the potential development of shale gas in the Karoo. The scientific assessment assembled a team of over 140 experts to evaluate these questions, clustered under 17 broad issues raised by the stakeholders. It is perhaps the most comprehensive study of its kind undertaken in South Africa.
Is there gas under the Karoo?
Definitely. The deep boreholes drilled in the 1970s revealed traces of gas, especially in the shales of the Whitehill Formation at the bottom of the Karoo geological sequence, several kilometres below the surface. At the time it was deemed non-recoverable because it is “tight” gas, reluctantly yielded by the rock. Technical advances, especially horizontal drilling and hydraulic fracturing (fracking), now make it possible to extract tight shale gas.
This does not mean that it’s economically viable to do so in the Karoo. Large volumes of gas have been claimed to be present based on sparse data, but the economically recoverable resource is much, much smaller. Best current estimates put it in the range 5 to 20 trillion cubic feet (tcf). By global standards, even the top end would be relatively small. For example, the proven reserves of conventional gas in the Mozambique Channel are 75 tcf. But by local standards, even the low end would be helpful; the offshore Mossgas field, now almost depleted, was less than 1 tcf.
What are the benefits of shale gas development?
Why use gas at all when there is abundant cheap solar and wind energy? Because adding quick-to-respond gas turbines into the South African energy mix increases the ability of the power generation system to use intermittent renewable energy sources in a way which slow-to-respond power sources like coal and nuclear cannot.
This technical policy decision has already been taken, as reflected in the country’s integrated resources plan; the only question is where to source the gas.
Relative to the use of imported gas, a viable Karoo shale gas find would save foreign exchange, accrue tax and employment benefits and improve national energy security. The number of jobs provided is quite small, especially for the low-skilled unemployed (a few hundred). The size of a shale gas industry in financial turnover terms is of the same order of magnitude as the existing Karoo farming and tourism industries. So it would make little sense to promote shale gas if it were to the significant detriment of existing, longer-term sectors.
What are the main concerns?
Fracking has been shown to increase the frequency of small earth tremors. But the Karoo is exceptionally seismically stable, and the increased risk of dangerously large earthquakes was judged by the scientific assessment to be small.
The risk to water resources is the biggest concern to all those involved. Each production well needs about 15 million litres of fluid to frack. The fluid is mostly water (it doesn’t have to be fresh), sand and a small quantity of potentially harmful chemicals. After fracking, the fluid is pumped back to the surface and stored for fracking the next well. Eventually the contaminated water must be purified, the hazardous material sent to a licensed disposal facility (currently there are none in the Karoo), and the clean water returned to the environment.
The greatest risk is that the fracking fluid leaks into the surface water and shallow aquifers used by people, livestock and the ecosystem, due to inadequate sealing of the upper parts of the borehole, or following a spill on the surface. These risks can be reduced, but not eliminated, by good engineering.
Current potable water resources in the Karoo are already fully allocated. The additional water requirements for shale gas development would either need to use water from local non-potable sources, such as deep saline groundwater, or water imported from outside the region.
The impact of shale gas development on the unique Karoo fauna and flora would mainly come from the accompanying habitat fragmentation and disturbance, rather than physical destruction. Each well-pad occupies just over a hectare, and the number per well-field is about 50. A small gas find may be one well-field, a big find may be five. So the area directly affected is a tiny fraction of the Karoo land area, even once the connecting roads and pipelines are considered. The exact location of the well-pads is quite flexible, which reduces the potential impact on both the rich Karoo cultural heritage resources and particular plant or animal populations.
The biggest and least tractable impact is likely to be social: the introduction of noise, traffic, lights, workers, work-seekers and their dependants into a formerly quiet environment, already struggling to service the resident population.
What questions remain?
Fracking in the Karoo has been presented as a “yes-no” decision that will be taken by government. In reality, the choices are more nuanced, far in the future, and not solely governmental. The scientific assessment asked “under what circumstances and under what regulations would it be sensible?’” It found no reason to completely eliminate shale gas as an option – if best practice is followed. The question that will determine if development proceeds is whether the resource is sufficiently attractive for the private sector to invest the billions of rand needed. Only exploration can answer that.
Robert Scholes, Professor Bob Scholes is a Systems Ecologist at the Global Change Institute (GCI), University of the Witwatersrand and Greg Schreiner,
Sustainability scientist, Council for Scientific and Industrial Research