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TRC Fraccing Report
The Taranaki Regional Council has undertaken a report on the hydrogeologic risks associated with "fraccing" in the O&G industry to inform Council environmental regulatory processes.
A synopsis of report findings is below and the full report is attached.
The agenda item background, which contains the officer report discussed on 24th November at the Committee meeting, is here
An assessment of the hydrogeologic risks associated with the practice of hydraulic fracturing of hydrocarbon reservoirs in Taranaki between 2000 and mid-2011 has been undertaken by the Taranaki Regional Council.
The assessment has been peer reviewed by a Senior Hydrogeologist with the Institute of Geological and Nuclear Sciences Ltd (GNS Science). This GNS Science peer review supports the assessment and conclusions of the Council.
The key findings of the Council’s assessment are as follows:
- Oil and gas companies operating in the Taranaki Region that have undertaken hydraulic fracturing operations between 2000 and mid-2011 provided data for this investigation and assessment.
- The data provided shows that during the period a total of 43 hydraulic fracturing activities were undertaken in 28 wells accessing oil and gas reservoirs that are up to 4 km underground, with the majority deeper than 2.4 km. The shallowest fracturing that has occurred is at 1.15 km at the Manutahi well sites and at 1.75 km at the Cheal well sites. These relatively shallow activities are assessed in more detail in the report.
- Most of the ingredients used in fracture fluids are found within products that are widely used in society, including in products used in homes. While most of the additives used in fracturing in their concentrated (pure) product form are toxic, as shown by the MSDS sheets attached to this report, they are diluted before use by the water carrier and,therefore, are present when injected into the environment in only relatively low concentrations. However, care is needed for some of these products even in low concentrations to avoid any potential for impacts on human health. Therefore, regulation of their use and disposal is appropriate. The typical percentage of additives in the fracture fluid is 2 % with the water carrier drawn from municipal supplies or consented river sources.
- If hydraulic fracturing operations are carried out properly, it is unlikely that contaminants will reach overlying freshwater aquifers in the Taranaki region. However, although unlikely it is not impossible. There are four potential routes for that to occur:
(1) leakage from the hydraulic fracturing well casing due to defective installation or cementing; (2) leakage through the geology overlying the hydrocarbon reservoir; (3) leakage from improper handling of chemicals used in the process and from hydraulic fracturing wastewaters ( i.e., flow back or produced water from the formation) brought back to the surface at the well site; or (4) a well blowout resulting in underground leakage into aquifers or surface recharge via spillage. The probability of a well blowout is very small, but cannot be completely discounted and has occurred during hydraulic fracturing operations in other countries.
This review of the hydraulic fracturing operations which have been conducted in the Taranaki Region between 2001 and mid-2011 has not found any evidence of related environmental problems.
The report concludes that there is little risk to freshwater aquifers from properly conducted hydraulic fracturing operations in the Taranaki Region.
This assumes a combination of natural geologic factors, the use of good practices by industry, and regulation by the Council as follows:
(i) Satisfactory methods for well design, installation, and operation are used by the petroleum hydrocarbon industry as well as quality control checks to ensure well installation integrity; (ii) Hydraulic fracturing occurs at relatively deep depths below freshwater aquifers (i.e., at thousands of metres below ground level, in comparison to freshwater depths which are in the order of hundreds of metres in many cases and less than approximately 1,000 m below ground level in all cases); (iii) The existence of natural petroleum hydrocarbon reservoir seals that trap the hydrocarbons in place; (iv) Substantial thicknesses and multiple layers of relatively low permeability geologic seals between the petroleum hydrocarbon reservoir and any freshwater aquifers;and(v) Operational management and monitoring by the petroleum hydrocarbon industry and regulation and monitoring (including sampling and auditing perational data) by the Council.
Although the risk that properly conducted hydraulic fracturing operations could adversely affect freshwater aquifers is very low, the level of risk is greater when hydraulic fracturing is carried out at relatively shallow depths below freshwater aquifers. In such case, a more stringent regulatory oversight is called for. The Council has decided to require resource consents, from August 2011, for all subsurface fracturing discharges to land beneath the region and will process these in accordance with the requirements of the Resource Management Act 1991. Compliance monitoring of the discharges will be undertaken and reported to the community.
Download the full report here