A study published Tuesday in the British journal Marine and Petroleum Geology finds underground wells used for shale exploration may cause water contamination.
A study from Research Fracking in Europe, or ReFINE, finds the structural casing of underground wells may present a risk to underground water supplies.
In the Marcellus shale play in the United States, the study found around 6 percent of the 8,000 wells had some sort of well integrity issue. In the United Kingdom, it found about one half of one percent of active wells showed evidence of failure.
With European countries looking to replicate U.S. success with shale exploration, the study found the data on well failure rates of onshore wells in Europe were "scarce."
Richard Davies, the project's leader from Durham University, said well integrity will be an issue if the shale narrative evolves in Europe.
"The data from the monitoring of active wells and the carrying out of periodic surveys of abandoned wells would help assess the impact of shale exploitation and it is important that the public should have access to this information," he said.
ReFINE found at least 4 million hydrocarbon wells have been drilled globally.