Main concerns about Hydraulic fracturing in the Karoo
The current public debate that gas exploration will take place in the Karoo has raised both concern and elation for a range of stakeholders. Those who regard gas exploration as a positive development allude to the employment prospects, while those who caution against it argue that gas exploration could be detrimental to the pristine way of life in the Karoo area. A recent study commissioned by the Water Research Commission (WRC) attempted to consolidate existing research in the field of gas development processes and the associated impact this might have on the environment. It summarised the current knowledge on hydraulic fracturing in the public domain and provided a review of South Africa’s regional geology and geohydrology.
The WRC study led by Prof Gideon Steyl, a research fellow at the Institute for Groundwater Studies (IGS) and a professor in Chemistry investigated what could happen should the process take place. In his report Prof Steyl indicates that the findings are neither totally comprehensive nor exhaustive, since little data is available in the public domain on hydraulic fracturing in South Africa.
To shed some light on the matter Prof Steyl and other research groups have visited Marcellus shale area in the USA where hydraulic fracturing is currently taking place. Sites visited included Pennsylvania drill rig in Whitneyville, the fracturing rig in Grover, the wellfield north of Whitneyville, the Williamsport Municipal Water Authority and the United States Geological Survey (USGS) office in Harrisburg.
Prof Steyl says, “The dolerite intrusions make the South African geology unique especially in comparison with the areas where shale gas occurs in America. The intrusive dolerites are present over about 390 000 km2 of the main Karoo Basin underlain by the Ecca Group (which increases the thermal maturity leading to the generation of dry gas) .This causes gasification of carbon in the shale that can only lead to gas being vented or being trapped in the sub–surface potentially making it unavailable for hydraulic fracturing’’.
Should the process be approved in South Africa, regulation to prevent environmental damage is the most important success factor, says Prof Steyl. A major concern in natural gas development is the prevention of migration of gas or other fluids out of the reservoir and into the overlying strata, particularly fresh water aquifers.
“Another major concern relates to the fact that the Karoo is already a water stressed area and hydraulic fracturing will consume a lot of such a scarce resource. For example, the Antrim gas well located Michigan requires 50 000 gallons (189 m3) of water,” says Dr Shafick Adams a Groundwater Research Manager at WRC.
“Proper management of produced water is particularly essential in protecting public health and the environment. In Michigan for example, produced water must managed and disposed of according to the strict rules, “says Prof Steyl.
Other main issues of concern include the identification of chemical additives. Spills of chemical additives or flowback water can have adverse environmental or public health impacts.
The WRC study recommends the remediation and handling of the terrain and even water purification should be closely monitored. Lessons can be drawn from Michigan where the laws and rules effectively protect water and other natural resources as well as public health and safety from potential adverse effects of hydraulic fracturing.
WRC report entitled “State of the Art: Fracking for Shale Gas Exploration in South Africa and the Impact of Water Resources” Report no. KV294/11
Contact Dr Shafick Adams email@example.com