Well Integrity

Well integrity is perhaps the single biggest failure in the Pepper inquiry report where these issues are not adequately covered and we have no indication this deficiency will be addressed in the SREBA.  It is not possible to guarantee the integrity of these wells over the long term and they will fail at some point, many in quite a short time. This is a major breach of Ecologically Sustainable development principles, which supposedly guide government decision making, and inter-generational equity responsibilities  as we must not create these wells when we know they will fail later creating problems for future generations.

  • The issue of well integrity is fundamental to the concept of safety in relation to wells and especially fracking wells.
  • There are some really significant issues in this area and it is fundamental to water risks as leaking wells can create water and air pollution and release toxins into the ground water.
  • The risks are high and the consequences extreme.
  • The Beetaloo basin has some unique characteristics that greatly increase the risks

These issues are particularly important in the Beetaloo basin area because of the extensive and interconnected nature of the water systems underlying the area. Pollutants from these wells could und up in the Katherine and Daly Rivers via these underground waterways as well as the Roper River.  Some of these chemicals carry very alarming cautions about their use in relation to human health and to aquatic systems.  E.g. Ethylene Glycol is listed as a chemical known to the State of California to cause birth defects or other reproductive harm.  Ulexite: Toxic to reproduction. May impair fertility. May cause harm to the unborn child, to name a couple.  Other chemicals injected into fracking wells include biocides with warning such as Highly toxic to aquatic organisms, must not be released into the environment, or warnings like H412 - Harmful to aquatic life with long lasting effects, or BE-9 is classified R51/53 which means Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment. This raises major concerns about the health of the underground water systems and their ongoing capacity to support pastoral and agricultural industries as well as the more significant concern that these aquatic systems are the source of drinking water for people right across the region.

Well integrity issues are further compounded by the fact the Beetaloo basin would appear to be the only gas province in the world where there is a highly salty, very hot aquifer layer sitting just above the prospective gas layers. This layer caused a flow to surface blow out at Tanumbirrini 1 on 24 August 2014. The Moroak sandstone aquifer is a major concern yet the government does not know anything about the salinity or the pressure as shown in correspondence with Minister Lawler in 2019.  See correspondence here.

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.

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 more information on Bacterial Corrosion issue here.

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 in detail yet it is very real and it is not clear it is being addressed in the SREBA. If you search for the word Bacteria in the Pepper report 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.