Photo: Annelie Coleman
This survey was preceded by another some 10 years ago. Can you share the results thereof?
Soekor, a then state-owned enterprise, searched for oil and gas resources contained in porous sandstone reservoirs in the Karoo Basin in the 1960s and 1970s. There were a few shows of oil and gas, but no significant discoveries were made, so the search moved offshore.
Gas was found on the continental shelf, and the Mossgas gas-to-liquid refinery near Mossel Bay was commissioned in the early 1990s. This resource was depleted and the refinery was mothballed a few years ago.
Around 2010, it was recognised that the Karoo Basin might contain significant resources of shale gas and that policies and regulations governing exploration and production should be formulated to prevent harm to the environment and society.
In 2015, the Department of Environmental Affairs commissioned a strategic environmental assessment (SEA) of shale gas development.
The SEA had a wide scope, including energy planning and security, surface and underground water resources, as well as ecology, agriculture, tourism, economy and human health. I was responsible for the chapter on earthquakes.
The SEA was essentially a ‘desktop’ study that summarised existing local and international knowledge, formulated broad recommendations, and identified knowledge gaps.
If the new survey uncovers sufficient resources, is fracking the only extraction method?
At this stage, we know very little about the petroleum resources in the south-central Karoo Basin. The goal of the investigation announced by Mantashe is to gather geophysical information regarding the regional geology and assess potential geological risks.
The seismic, magnetotelluric and magnetic data are gathered either on the earth’s surface or by airborne surveys; the investigation does not include any drilling or extraction of oil or gas.
The knowledge gained will enable Mantashe’s department to make informed decisions regarding the issuing of exploration rights. Hydraulic fracturing (fracking) is currently the only viable means to extract hydrocarbons from deeply buried shale rock.
However, we do not know if there is sufficient petroleum in the Karoo Basin to warrant exploitation and whether it is stored in sandstone, shale, or both. Hence, we do not know whether fracking will be required.
Why is fracking such a contentious issue worldwide?
Firstly, there is growing global opposition to the consumption of fossil fuels (coal, oil, gas) regardless of the way in which they are extracted, as their production and combustion produces carbon dioxide and other greenhouse gases that contribute to climate change and extreme weather events.
There is a strong drive to replace fossil-based fuels and energy with renewable energy like hydro, solar, wind and geothermal.
Secondly, fracking has opened up new areas for production of oil and gas, which is accompanied by all the risks and opportunities brought by any change or development, be it an irrigation scheme or forestry plantation, or a large dam, wind or solar farm.
The risks that are peculiar to fracking include an increased demand for water (to hydro-fracture the rock), the unsafe disposal of any polluted water and chemicals, and the possibility that fracking may trigger damaging earthquakes.
What is the potential impact of fracking on the environment and water in the Karoo, a biodiversity hotspot, and how can it be mitigated?
This was one of the issues specifically addressed in the SEA. The area of potential shale gas development was mapped in terms of ecological and biodiversity importance and sensitivity (EBDIS). Seven different biomes, 58 vegetation types, 119 endemic or near-endemic plant species, and 20 threatened animal species were recorded.
It was recommended that areas that contain extremely sensitive features and are irreplaceable (EBDIS-1) are avoided and that steps be taken to limit harm in other areas. Protected and EBIDS-1 areas comprise 5% and 13% of the shale gas development area, respectively.
Regulations that provide guidance on precautionary measures for hydraulic fracturing and water use are currently being developed by the Department of Forestry, Fisheries and the Environment and the Department of Water and Sanitation, respectively.
What is the impact on the agriculture sector, considering that large areas are already degraded due to overgrazing?
This was another one of the issues that was specifically addressed in the SEA. Well pads used to drill exploration, appraisal and production wells are relatively small, perhaps two hectares, and many kilometres apart. Their direct impact on farming activities is expected to be small.
The biggest risk relates to the competing use and potential contamination of water resources. This can be managed by careful treatment of wastewater, safe disposal of waste products, and the sealing of all boreholes so that there is no leakage into aquifers.
Furthermore, development of any shale gas resource will likely draw new people to the region, and greater traffic could cause a loss of privacy and increase the risk of crime.
On the other hand, shale gas exploration and production could actually produce more groundwater or provide a case to build pipelines to bring water to the region.
Furthermore, shale gas development could provide opportunities to earn income by providing accommodation to workers, renting property and creating jobs.
What does the process of fracking entail?
The Karoo is dotted with boreholes that extract groundwater from aquifers. These are rocks that are porous and permeable. A rock is porous if there are minute cavities that can store fluids; permeable means that the cavities are connected so that fluids can flow through the rock.
Ideally, the groundwater is replenished by rainfall or rivers. Aquifers are typically sandstones, or rocks that have been naturally fractured by geological faults.
The boreholes are generally vertical and, at most, a few hundred metres deep.
Conventionally, oil and gas are extracted from porous and permeable rocks like sandstones. However, the boreholes are usually much deeper than groundwater holes (typically 2km to 4km), requiring much more powerful drills.
In the last 20 or so years, ‘unconventional’ hydraulic fracturing technology has been developed that makes it possible to extract oil and gas from rocks that are not permeable, such as mudstones and shales.
Two major technical advances have made this possible. First, technology to steer the drill bit so that the borehole’s trajectory can be changed from vertical to horizontal.
This makes it possible to penetrate the flat-lying shale beds for distances of several kilometres from the borehole collar. Many holes can radiate from a single well pad, tapping an area of perhaps 10km2.
Secondly, the water-filled hole is pressurised section-by-section at pressures great enough to fracture the rock artificially. Tiny, hard particles are forced into the cracks so that they do not close entirely once the extra pressure is removed, allowing gas or oil to seep out. Chemicals may be injected to encourage the flow of viscous fluids.
In your opinion, should South Africa explore the matter of fracking in the Karoo or not?
I personally believe that we should explore the Karoo Basin to establish how much oil
and gas is actually present, and if it can be economically exploited in a way that benefits
our country without harming the environment.
If any resources are found, what will the next step be?
It all depends on how much is found and where it is. It is normal to secure long-term offtake agreements with customers, such as energy utilities, prior to investing the large sums of money required to develop a shale gas resource.
What is the lifespan of a fracking well, and what happens to it after it reaches the end of its life cycle?
The lifespan of a typical gas field is 10 to 30 years. All boreholes should be carefully plugged to prevent any contamination of aquifers or the environment; any pipelines and tanks serving the well pad should be removed; and the land rehabilitated and returned to fruitful use.
How would you ideally like fracking to be managed in the Karoo?
The best outcome is a thriving oil and gas industry that provides decent work for thousands of people in the Karoo. They will drill and, if necessary, frack the boreholes, extract the hydrocarbons, build and operate power stations and petrochemical plants, and regulate and service the industry and its employees.
Exploration, production and rehabilitation activities will be governed by regulations and guidelines that eliminate or limit harm to the environment and people and the impact on activities such as farming or tourism. Draft regulations are being finalised and public comment will be solicited.
In this ideal world, explorers and operators will comply meticulously and willingly with the guidelines and regulations. Nevertheless, measures will be put in place to monitor compliance and give early warning of any failure.
The hydrocarbons will be used to provide affordable energy and produce products such as waxes and plastics. Depleted underground reservoirs will be used to store carbon dioxide, mitigating global warming.
Company and personal taxes will contribute to the delivery of social services such as education and healthcare. A proportion of earnings will be deposited in a trust fund to ensure that the land is restored and returned to productive use once the resource is depleted.
Our need to import oil and gas will be reduced, thereby improving the national balance of payments. A sovereign wealth fund will be created and used for economic development to sustain communities once the oil and gas are depleted.
Email Prof Raymond Durrheim at [email protected].
