Shale gas: fracking
Shale Gas. Peter Roswewarne corporate consultant SRK Consulting (SA)
Peter Rosewarne presented “Karoo Shale Gas Exploration: Groundwater Occurrence, Supply, Impact Scenarios and Protection” at the conference.

Yesterday at the Unconventional Gas conference in Cape Town, new developments emerged during a debate on using hydraulic fracturing (fracking) technology to release shale gas in the Karoo region in South Africa.

SRK Consulting’s independent corporate consultant Peter Rosewarne informed attendees that the developments include the publication of the updated Regulations for Petroleum Exploration and Operation 2015.

Another development is the commissioning of a two-year Strategic Environmental Assessment (SEA) by the Department of Environment Affairs.

Further to this, the Karoo Groundwater Expert Group (KGEG) has made substantial progress in filling gaps in the knowledge base on groundwater in some of the areas where companies have applied for shale gas exploration permits in South Africa.

Shale gas fracking

Shale gas fracking usually takes place at depths of between about 1,500 metres and 4,500 metres, where the shale gas formations occur, depending on the geology of each licence area.

Deep core holes drilled by SOEKOR, the state-owned oil and gas exploration company, in the 1960s and 1970s, have provided interesting but sparse information on interceptions of hot artesian groundwater (measuring temperatures of 46o to 77o centigrade and flowing at about three litres per second) at depths of over 4,000 metres.

Such flows were only recorded from wells below the Great Escarpment.

Groundwater concerns

The unknown factors that still need further investigation, said Rosewarne, include deep groundwater occurrence, origin, quality, temperature, pressure, interconnectivity between such groundwater and shallow aquifers, and the influence of the numerous dolerite intrusions that occur in much of the Karoo.

The updated petroleum exploration and operations regulations recognise concerns around shale gas fracking and provide for, inter alia, exclusion zones around well-fields, boreholes, wetlands and springs, requirements for baseline sampling and monitoring, and well closure.

Rosewarne added that qualitatively, it can already be hypothesised that the risks from shale gas exploration or production will vary between licence areas as these ‘unknowns’ vary.

Key risks to water quality were also likely to include surface spills of chemicals during transport and storage at depots and well heads, as well as the legacy of long-abandoned wells.

Shale gas fracking technology developments

According to Rosewarne, by the time that exploration or production takes place in the Karoo, if they do, technology may have progressed to a point where water is not required for the shale gas fracking process, making some concerns redundant.

He added that new work, such as deep geophysics and drilling, was now required so that sound scientific assessments could be made on environmental risks. These should inform the far-reaching decisions that need to be made regarding the viability of shale gas exploration and production in the Karoo.

Further research underway

The Karoo Research Initiative Project, being led by the University of the Witwatersrand, will see three deep core holes drilled to 2,000 metres each – one in the western Karoo and two in the eastern Karoo.

These will provide valuable geologic and stratigraphic information from fresh core (as against the decades-old and deteriorated SOEKOR cores) and, hopefully, information on deep groundwater occurrence and properties.

“So far, some academic studies have tended to apply only default values and assumptions to the shale gas debate, which has often led to predictions of a worst-case scenario that envisages widespread contamination of Karoo aquifers,” said Rosewarne.

The Water Research Commission is funding projects investigating aquifer vulnerability, deep-shallow groundwater interaction and the impact of unconventional gas mining on water resources.

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