Thursday, 2 January 2014

FOI information from DECC - Well integrity in the UK

A recent FOI response from DECC regarding historic drilling in the UK makes for interesting reading. I've often mentioned the thousands of existing wells in the UK, both onshore and offshore, which have been drilled, operated and abandoned without incident, and the implications these have for future shale gas drilling in the UK. I've taken the liberty of doing a wholesale copy-and-paste, because this is fairly fundamental stuff:

(Questions in italics, DECC responses in bold)

The first question discusses offshore wells:
In relation to offshore gas/oil wells which fall under UK Government jurisdiction:
a. How many wells are currently in operation (wells not rigs)?

  • There are about 25 offshore wells currently drilling
  • Some 3360 offshore wells have been completed for production (ie are either producing oil and /or gas or are shut-in)

b. How many abandoned wells are there?

  • Approximately 6500

c. How many operating wells with cementation integrity issues have been reported within the last 5 years?

  • DECC does not hold this data

d. How many abandoned wells with cementation integrity issues have been reported within the last 5 years?

  • DECC does not hold this data

e. How many leaks from operating wells have been reported within the last 5 years?

  • Any release of oil and/or chemicals from offshore installations, including wells and pipelines, must be reported to DECC Offshore Oil and Gas Environment and Decommissioning (OGED) using a Petroleum Operations Notice No.1 (PON1). Details of PON1s received by the Department are published on our website at the following link https://www.gov.uk/oil-and-gas-environmental-data#pon-1-data. As far as DECC OGED is aware, no leaks have been reported for operating wells during the last five years, but a leak was reported from a suspended well in the Elgin field that attracted media attention (further details can be found at https://www.gov.uk/government/news/elgin-gas-release-government-interest-group) and a recent review of all suspended wells on the UKCS confirmed that there were minor gas leaks from four shut-in production wells.

f. How many leaks from abandoned wells have been reported within the last 5 years?


  • As far as DECC OGED is aware, there have been no reports of leaks from abandoned wells in the last 5 years.

g. Does the UK Government keep records of abandoned wells with leaks / cementation integrity issues?

  • Information in relation to leaks from abandoned wells is held by DECC.


The second question discusses onshore wells
In relation to onshore gas/oil wells in the UK:
a. How many wells are currently in operation?

  • DECC requires monthly production reporting on a field basis, not a well basis. Reporting individual well operations is not required on licences issued before 1965, but we estimate there are currently about 300 onshore wells in production.

b. How many abandoned wells are there?

  • Records for wells drilled before the 1960’s are not reliable so we can only estimate that there are about 1500 abandoned wells.

c. How many operating wells with cementation integrity issues have been reported within the last 5 years?

  • None

d. Where are these wells?

  • Not Applicable

e. How many abandoned wells with cementation integrity issues have been reported within the last 5 years?

  • One

f. Where are these wells?

  • This was a well in Stafforshire and the integrity issues have subsequently been dealt with.

g. How many leaks from operating wells have been reported within the last 5 years?

  • None

h. How many leaks from abandoned wells have been reported within the last 5 years?

  • None

i. Does the UK Government keep records of abandoned wells with leaks / cementation integrity issues?

  • DECC does not keep such records – but regularly liaises with the Health & Safety Executive in relation to such issues.

The final questions relate to hydraulic fracturing:
3. During gas / oil exploration for conventional targets, are wells hydraulically fractured?

  • Yes, some are.

4. During gas / oil exploration for unconventional targets (e.g. shale, coal bed methane), are wells hydraulically fractured using exactly the same technique for conventional targets?

  • The volume of injected fluid is significantly bigger for shale gas, but similar and small volume for conventional and coalbed methane.

5. During gas / oil exploration for unconventional targets (e.g. shale, coal bed methane), does high pressure, high volume slick water hydraulic fracturing (often referred to as fracking) take place?

  • Yes, for shales.

6. If yes, please provide evidence to state at what point of the process this occurs (e.g. initial drilling, pressure testing, sampling etc).

3 comments:

  1. Michael Roberts2 January 2014 14:59

    Perhaps no comment is the best comment :) So much for safety concerns on leakage

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  2. Maybe a significant question is - what monitoring is in place either by the industry or by the regulatory authorities to ensure that well integrity issues and leaks are discovered.

    A pity you didn't ask this. Perhaps you would like to do this now, Mr Verdon. Then we can have a better interpretation of the current response.

    Obviously DECC do not consider well casing deformation (Preese Hall) as a cementation issue. And was it not a casing issue that has led to the closedown and proposed abandonment of the Anna's Road well?

    The questions and answers also do not differentiate between exploratory, appraisal and production wells. I would have thought the additional data split down appropriately might have been of interest. We know the well number split from DECC statistics.

    There is also no question or answer about how many onshore wells have been hydraulically fractured or stimulated. That would have also been an interesting and pertinent question. The answer would have come back that DECC do not know. However, as DECC confirm that shale hydraulic fracturing is of a different nature to what has happened so far onshore in the UK (apart from the ill-fated Preese Hall) this might have not given much of a pointer as to what might occur with shale gas and oil wells.

    All in all, not a very scientific approach, Mr V, and not one with enough data to justify any conclusions whatsoever.

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    Replies
    1. Well integrity falls within the remit of the HSE. However, it is simpler to reply to your question with one of my own: does anyone see leakage of gas and/or oil around these existing oil fields? Any complaints at all of problems with groundwater near these sites? After all, this is what the activists claim will happen, isn't it? Many of these fields are not that far from built up areas, or in the case of Wytch Farm, a very environmentally sensitive area (Studland or Poole Harbour).

      The anti-fracking activist literature is filled with claims about wellbore integrity ("5% of wells fail immediately", "50% of wells fail within 20 years", "ALL wells fail eventually", etc etc). The evidence for these claims simply does not stack up.

      With respect to current developments, the BGS are already conducting groundwater surveys across the areas where shale gas development is likely. Further tests will be conducted during and after drilling, meaning that in the unlikely event of a well having problems, this can be identified immediately, and the appropriate remediation and repair work conducted. These tests have already been conducted at Balcombe, for example (you'll note that the "protectors" actually prevented the EA from going about their work).

      Approximately 200 onshore wells in the UK have been hydraulically fractured. The volumes used for these stimulations were smaller than what is proposed for future shale developments. However, the choice of completion method(s) in the toes of lateral wells have little bearing on casing integrity through the 2 - 3km vertical section of the well, and especially not in the intermediate and near surface casing strings, which are the zones of relevance for groundwater contamination. So data from existing wells is in fact very relevant in this regard.

      The casing deformation at Preese Hall was entirely within the production zone, where the casing is perforated to allow fluids to move from the rock formation into the well (and vice versa during stimulation). In fact, the deformation was entirely below the zone where they were stimulating. It is irrelevant to talk about wellbore integrity in a section of the well that has been deliberately perforated to allow gas to flow.

      As regards the Anna's road well, my understanding was that a packer, inserted during pressure testing, of the well became stuck, and they were not able to remove it. This has no bearing on well integrity.

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