The issue of well integrity is fundamental to the concept of safety in relation to wells and especially fracking wells. This is perhaps the single biggest failure in the Pepper inquiry report where these issues are glossed over. It is not possible to guarantee the integrity of these wells over the long term and they will fail at some point. This is a major breach of inter-generational responsibilities as we must not create these wells when we know they will fail later. There are some really significant issues in this area and it is fundamental to water risks as leaking wells create water and air pollution.
There are many questions about these risks to well integrity in the short to medium term that need to be answered by the SREBA. Questions we have raised about corrosion in wells in QLD have not been answered and the information has been moved behind a firewall. See information on Corrosion.
Estimates of well failure rates vary although the more conservative well failure rates found in the literature are between 4.6% and 8.9%. Further, a study from Alberta, Canada of more than 315,000 oil, gas and injection wells of various ages, (Watson and Bachu, 2009), shows that ‘injection wells’ into which liquids or gasses are pumped are 2-3 times more likely to leak than conventional ‘production wells’.
The same study found that horizontal or inclined wells are observed to have significantly higher failure rates than vertical wells. Clearly there are going to be failures.
A key part of the problem is acidic groundwater and especially bacteria that create Hydrogen Sulphide (H2S) which creates Sulphuric acid and dissolves steel and concrete over time. Territorians were introduced to this when the Adelaide River bridge on the Arhnem Highway partially collapsed in 1998. We have a range of bacteria in soils and water which cause this phenomenon and so wells that are put in place and sealed to stop inter aquifer contamination and leakage of gas and contaminants just will not last. This means government s have to pick up the bills, yet another example of the companies maximising their profits while the public carry all the risks. Leaking wells and governments having to fund efforts to mitigate the damage is becoming a major issue in Pennsylvannia where deep shale fracking, similar in many ways to the Beetaloo deposits.
The Pepper Inquiry does not discuss this issue yet it is very real. If you search for the word Bacteria in the document you will soon realise this is a major oversight. Until this issue is clarified we cannot take the risk of polluting waterways and distorting water system integrity now or in the future. This issue appears to be a case of the mining interests not wanting to take long term responsibility for their actions as they will have made their money and left before the problems impact. When you consider the pollutants in the water in fracking wells the risks are extraordinary.
Well integrity is of concern in the NT because some groundwater environments in the NT are naturally corrosive. An example of the effect of corrosive water on cementing and casing in the NT is provided by deep oil exploration wells (McDills and Dakota) drilled in the Perdika/Great Artesian Basin in the 1960s. (The Perdika Basin is one of the prospective unconventional shale gas areas of the NT). Now, some fifty years later, the steel casing has almost entirely corroded away, resulting in inter-aquifer contamination. This well required expensive rehabilitation works to stem artesian flow (Humphreys and Kunde, 2004). This single bore cost the Territory and Commonwealth Governments $500,000 to plug as the company responsible for the well was insolvent ( NT branch
This is a major concern for indigenous groups who have very special cultural bonds with water and water stories and take a very long-term view in relation to consequences of actions.