The British
Geological Survey (BGS) in partnership with the Researching Fracking in
Europe consortium has published a review of global oil and gas well
integrity*. The study covers some 25 on well barrier and integrity
failure datasets from the estimated four million onshore hydrocarbon
wells drilled globally. The BGS’ Rob Ward said, ‘Hydrocarbon well
integrity problems are a real issue. While there has been only one
reported incidence of a UK onshore well causing pollution due to
integrity failure, there is a lack of information for the many hundreds
of other abandoned wells.’
Abandoned
wells in the UK are sealed with cement, cut below the surface and
buried, but are not subsequently monitored. The reported numbers are
likely to underestimate the number of wells that have failed. Knowledge
of the risks would be better if systematic, long-term monitoring data
from both active and abandoned wells were in the public domain. It is
also probable that some wells in the UK and Europe will become orphaned
and it is important that the appropriate financial and monitoring
processes are in place so that legacy issues associated with the
drilling of wells for shale gas and oil are minimised.
The risks
associated with well integrity failure need to be taken very seriously.
Wells drilled onshore in the future (including those for shale gas)
will be subject to strict regulatory controls that require a detailed
environmental risk assessment to be carried out, approval of well
design by an independent inspector, well integrity testing and
effective groundwater monitoring.
* Oil and gas wells and their integrity: Implications for shale and unconventional resource exploitation. March 2014 Journal of Marine and Petroleum Geology.
This article originally appeared in Oil IT Journal 2014 Issue # 4.
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