Report notes four fracking instances in South

The use of hydraulic fracturing of rock, or ''fracking'', appears more widespread than originally thought, with some instances of fracking in Otago and earlier in Southland coming to light.

All four attempts were unsuccessful in their quests to release coal seam gas, test rock pressure or try to improve water yields.

In December Dr Jan Wright, the Parliamentary Commissioner for the Environment, released an interim report evaluating the environmental impacts of fracking around the country.

While concentrating research on Taranaki, Dr Wright also found recent fracking for groundwater by the Otago Regional Council (ORC) in 2011, rock pressure testing during construction of the Clyde dam in 1983 and two fracking attempts for coal seam gas in Ohai, Southland, in 1995.

The public and environmental outcry over fracking, in which water and chemicals are mixed and injected at high pressure into rock to fracture it and release otherwise trapped oil or gas deposits, is mostly about chemicals entering water tables, or disposal of chemicals at ground level.

While Dr Wright's 120-page interim report found no reason for a moratorium on fracking around New Zealand, and emphasised risk management, she raised enough concerns to warrant further investigation by her.

Dr Wright's interim report said fracking could be used for purposes other than oil and gas extraction, and said the ORC fracked a water bore in Central Otago in 2011, to try to improve its yield, but was unsuccessful.

''This is unlikely to have been the only use of fracking to improve groundwater flow in New Zealand,'' Dr Wright said, noting the fracking of water bores was ''common'' in some drier parts of the world.

The ORC said in a 60-page March 2012 publication ''Groundwater exploration in the Ida Valley'' that at one of two bore holes it tried fracking ''to try to improve its [water] yield''.

Otago Regional Council director resource management Selva Selvarajah was contacted and said the hydrofracking at the Cresslea bore, in 2011, was done without chemicals, which environmentalists believe could contaminate groundwater.

The Ida test bore hole was cement-lined and left for a month before workers ''applied high pressure water'' until the rock fractured.

Water yields did not subsequently increase.

Dr Selvarajah said while the process was relatively common in Australia, he understood the Ida Valley hydrofracking was the first time it had been undertaken in New Zealand.

It did not require resource consent, as it came under specific rules for bore drilling in the ORC's water plan.

''[But] when it comes to fracking for oil and gas, resource consents will be very stringent on dealing with any adverse effects on the environmental systems,'' Dr Selvarajah said.

He described hydrofracking as a ''minor activity''. In Dr Wright's report's appendix of fracking operations, she lists 45 instances in Taranaki from 1989 to 2012, eight in the Waikato since 2007 and two in Ohai, in Southland in 1995.

The Ohai drilling by Southgas Resources was two holes, once of which was fracked three times at a depth of 480m and the second four times at 350m.

Dr Murry Cave has supplied reports on the Ohai work, and when contacted said while chemicals were used in 1995, the additives were less than 0.05% of the entire mix, and a that proportion would not be considered toxic.

It is the depth and proximity to groundwater aquifers which are of concern to environmentalists. The industry counters by saying fracking usually takes place hundreds of metres below aquifers, which are relatively closer to ground level.

In dealing with wastewater from fracking injection, Dr Wright said it could be sent to an industrial waste facility for treatment, held in evaporation ponds or be discharged directly. She noted that at Southgas Resources' holes in Ohai, they reported ''wastewater was discharged into a [unnamed] stream near two Southland coal seam wells'' after fracking.

''The Southland coal seam gas wells were unsuccessful, so were abandoned,'' the report said.

Listed L&M Energy, while not using fracking, is exploring for coal seam gas around Ohai and Kaitangata in Otago.

Fracking is only used to boost production flows, as opposed to being an exploration method.

In a note of ''other uses'' for fracking, Dr Wright said that some fracking did not use any proppants or chemicals.

Dr Wright said other uses for fracking included testing for rock strength and in 1983 during the Clyde dam construction, it was used to measure stress.

''Sections of a borehole were sealed off and pressurised until the surrounding rock failed,'' she said.

While 21 field tests were completed at the Clyde dam, she said ''few meaningful stress results were obtained''.

The ORC said in the Ida Valley groundwater report the availability of the aerial geophysical survey data gave it the opportunity to locate potential groundwater sources with greater confidence.

In 2007-08, the ORC paid about half of gold explorer Glass Earth Gold's $4 million geophysical aerial survey costs, covering large swathes of Otago.

- simon.hartley@odt.co.nz