Special Digest


4000 Holes in Blackpool Lancashire

Pollution prospects in the Bowland Shale PEDL165 area.

A recent communication by Cuadrilla has confirmed that in the 1180 sq km licence area they hold - PEDL165 - they estimate the development (over some decades) of 100 well pads each of 2 hectares.

As we know from their earlier announcements they anticipate multi-layer drilling into the Bowland Shale we are confident that these 100 well pads could each contain ten or twelve vertical bores, each with 3 or 4 laterals sprouting horizontally.

We feel it’s fair, then to use a working estimate of 4,000 wells in Cuadrilla’s patch.

The recent study published by Durham University and ReFINE looked at the current state of onshore wells in the UK. It found by looking at a set of data from around the world - “the percentage of wells that have had some form of well barrier or integrity failure is highly variable (1.9%-75%). Of the 8030 wells targeting the Marcellus shale inspected in Pennsylvania between 2005 and 2013, 6.3% of these have been reported to the authorities for infringements related to well barrier or integrity failure. In a separate study of 3533 Pennsylvanian wells monitored between 2008 and 2011, there were 85 examples of cement or casing failures, 4 blowouts and 2 examples of gas venting.”

If the Marcellus shale example were taken as a guide, we could then expect perhaps out of 4,000 Cuadilla wells 6.3% or around 250 might have problems. Or we could expect rather more than in Pennsylvania, ie about 100 well problems. This direct comparison might not be fair, since as the Durham report says, the US wells are of varying age and design. It might - and will - be said that UK regulation is far better. On our side, of course, we do not believe that.

The study went on to look for around 2150 onshore wells, the earliest dating back to 1902. The report said - “UK regulations, like those of other jurisdictions, include reclamation of the well site after well abandonment. As such, there is no visible evidence of 65.2% of these well sites on the land surface today and monitoring is not carried out. The ownership of up to 53% of wells in the UK is unclear; we estimate that between 50 and 100 are orphaned. Of 143 active UK wells that were producing at the end of 2000, one has evidence of a well integrity failure.”

(Note - Orphaned means in the context of this report wells for which the operator has gone out of business or is insolvent.As the above confirms, there are many more in the UK where the location of the well can not be identified, or where the responsible operator isn't known.)

Firstly, it is obvious that UK regulations are not adequate to handle abandoned wells. It could be said that since some of these wells are so old this is not a fair comment. Lord Lawson said as much in a Lords Economic Affairs Committee late last year. Co-author of the Durham report Professor Richard Davies put him right. “No, some of these wells have been drilled in the past five or 10 years.” (In the same evidence session Professor Davies quoted Canada as a study example, he said some 4.6% of wells had leaked.)

It remains true that there is no monitoring of abandoned wells. The Durham report says - "In the UK there have been a small number of reported pollution incidents associated with active wells and none with inactive abandoned wells. This could therefore indicate that pollution is not a common event, but one should bear in mind that monitoring of abandoned wells does not take place in the UK (or any other jurisdiction that we know of) and less visible pollutants such as methane leaks are unlikely to be reported. It is possible that well integrity failure may be more widespread than the presently limited data show.”

So we have NO IDEA how many of the abandoned wells are leaking. (We DO know - or at least we have an estimate - that out of some 250,000 abandoned coal workings many are leaking, posing a threat to water resources. Also - the Durham report again - “In some areas, abandoned mine workings also liberate methane, and emissions from abandoned UK coal mines were estimated to be 14 million m3 of methane in 2008 (UNFCCC, 2010)."

The body of the report says that over a four year period, out of 134 active onshore oil or gas wells there were nine pollution incidents and two example of well integrity failure. It should be pointed out that all the pollution incidents came from leaking oil pipelines. In other words we have no idea how many leaks there were, some going undetected no doubt, from gas pipelines. Note also the report body contradicts the abstract (and resulting media coverage) that only one well has “failed”. The report conclusion says that two separate wells had integrity failure (Hatfield Blowout and Singleton Oil Field). However this is stated to be likely an underestimate.

It is worth quoting the report conclusion in full - it raises issues not only about the inadequacy of current regulation and monitoring regarding abandonment of wells but the need for financial measures to be put in place to deal with future problems. The government has, of course, recently refused to do this.

“Well barrier and integrity failure is a reasonably welldocumented problem for conventional hydrocarbon extraction and the data we report show that it is an important issue for unconventional gas wells as well. It is apparent, however, that few data exist in the public domain for the failure rates of onshorewells in Europe. It is also unclear which of the datasets used in this study will be the most appropriate analogues for well barrier and integrity failure rates at shale gas production sites in the UK and Europe.

Only 2 wells in the UK have recorded well integrity failure (Hatfield Blowout and Singleton Oil Field) but this figure is based only on data that were publicly available or accessible through UK Environment Agency and only out of the minority of UK wells which were active. To the best of our knowledge and in line with other jurisdictions (e.g. Alberta, Canada) abandoned wells in the UK are sealed with cement, cut below the surface and buried, but are not subsequently monitored. This number is therefore likely to be an underestimate of the actual number of wells that have experienced integrity failure. A much tighter constraint on the risks and impacts would be obtainable if systematic, long-term monitoring data for both active and abandoned well sites were in the public domain. It is likely that well barrier failure will occur in a small number of wells and this could in some instances lead to some form of environmental contamination. Furthermore, it is likely that, in the future, some wells in the UK and Europe will become orphaned. It is important therefore that the appropriate financial and monitoring processes are in place, particularly after well abandonment, so that legacy issues associated with the drilling of wells for shale gas and oil are minimised.”

(Note - the report distinguishes between “well integrity failure” and “well barrier failure”. Well barrier failure means “the failure of individual or multiple well barriers (e.g. production tubing, casing, cement) that has not resulted in a detectable leak into the surrounding environment”. Well integrity failure means “all well barriers fail, establishing a pathway that enables leakage into the surrounding environment”. )

In my view the above conclusion needs rewording, to suggest that a small percentage of wells will have well barrier failure, not necessarily a small number, especially if shale gas production went large-scale. We might add to the report’s data two instances of problems with wells, now well-documented. Cuadrilla’s at Preese Hall and Anna’s Road in the Fylde. Neither of these has yet been formally abandoned, and no agreement has been made as to exactly what measures will be in place for abandonment.

Coming back to the original intention of predicting problems of 4,000 wells in Cuadrilla’s Bowland shale patch.

If in a four year period out of 134 active wells there were pollution incidents from 9 and well integrity failure at 2, from 4,000 wells, each active over, say, a 20 year period, might we expect the Durham data to scale up? Could we expect in a four year period 270 pollution incidents? 60 well integrity failures? Over twenty years five times that number? 1350 incidents and 300 well integrity failures?

Or should we compare with Canada’s 4.6% of wells leaking? IE some 180-odd wells leaking in Cuadrilla’s patch alone?

Our opponents may dispute these suggested figures. They could point out, for example, that since most leaks reported are pipeline failures the clustering of wells on pads and hence pipelines could greatly reduce the projection. This, of course, would be to ignore the fact that many leaks of methane would not be detectable, and we know of few incidents of leaking abandoned wells because they are not monitored. However, they can not use the pad cluster argument to counter the fact that many wills WILL have well boundary failures, and many will have well integrity failures. This is the legacy the frackers will leave us.

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