Fracking has inherent engineering challenges.
The process employs a thin rigid tube passing thousands of metres underground. These cross aquifers as well as cracks and faults in the rocks. Our water supply relies on that long thin tube not cracking. As soon as fracturing starts there are low grade earth tremors produced. Some are of greater strength and where the well crosses a fault it would be reasonable to expect some slippage of the fault. Cement is not sufficiently flexible to cope with the shearing forces and the pipe itself may be damaged. To prevent leaks, the layers of cement injected around the layers of piping must be complete without bubbles, cracks or shrinkage. The forces carting on the integrity of the cement especially during fracturing are such that most wells will fail in time allowing methane and other gases to be released.
Our only frack in UK to date has seen that well casing leak. This is a common occurrence and increases over time from about 5% to as much as 60% over the years. The drilling company involved, Cuardrilla Resources were economical with the truth in this, their first opportunity to be transparent about the results of UK activity.
Halliburton were the company that pioneered fracking. They developed the pipes and the chemical mixtures and they are a major drilling company. It was their part that failed in the Gulf of Mexico massive oil spill blamed on BP. Halliburton had knowingly under-engineered the well pipe with fewer layers and had modelled the reductions. To avoid blame they destroyed the evidence but paid a $1billion fine.
Here are some more links related to pipework leakage which you will find of interest:
In this video Anthony Ingraffea tells us industry sources estimate that 30% or more of all gas/oil wells are leaking because of faulty cement/casing.
A comprehensive review of the evidence offers some explanations about why the well casings leak increasingly with time. A detailed analysis looking at the risks of tracking and well integrity.They warn that even with proper construction, underground leaks of methane into ground water occur. They consider this being perhaps, the greatest risk from fracking.
Even the oil and gas industry recognise the well casings leak and may do so into aquifers.
Everyone agrees that the well casings leak.