Q&A No.712 - Well Abandonment Guidelines

0 votes

Dear COIN Members,

CNRL are looking for a comparison of different well abandonment guidelines across different regulatory bodies.  We are particularly interested in abandonment barrier length requirements, both in the wellbore and in the annulus.
 
Have any COIN members already performed such a comparison that they might be prepared to share with CNRL?
 
Any assistance or guidance would be most appreciated.
 
James Richards
Drilling Engineer
CNRL
asked Apr 15, 2016 in COIN by James Richards (120 points)

4 Answers

0 votes
James,

Below is a response from Simon Sparke, one of our COIN members now working with TGT Oil in Abu Dhabi as their Well Integrity Technical Domain Champion.  

Simon writes:

I did just this a couple of years ago and have it buried in my "highly organized filing system". They might be slightly out of date, but will give a flavor of requirements. (To follow)

However,  the trend is to follow four principle set of regulations:

Oil and Gas Uk

Norsok D-D010

Nopsa (Australia)

Alberta

While they all tend to follow the same requirement for 2 x 30m plugs + an environmental barrier, the need for verification changes.

Regards

Simon
answered Apr 18, 2016 by Fiona Curley (1,480 points)
Thanks for the infomation Simon.  That's exactly what we were looking for.  Interesting to see how the requirements are broadly the same despite very different environments that the different sets of regulations apply to.
0 votes
Though I am not aware Maersk as not done any comparative studies, I remember Jules Schoenmakers (Shell) touched on this topic briefly during his 2014 SPE presentation in Bergen- see page 9.

It may be worth contacting him as a starting point.

Regards,

Abim
answered Apr 18, 2016 by Abim Oladipo (140 points)
Good suggestion, thanks Abim.
0 votes

Hi James,

I made contact with Jules Schoenmakers of Shell who gave the presentation in question to the SPE in May 2014 during their Global Integrated Workship Series - The Challenges of Well Integrity in a Subsea Environment.  He touched on this subject on Slide No.9, which he shares here; but does not havea  similar overview for annular spaces.

 

Regards

Fiona

answered Apr 18, 2016 by Fiona Curley (1,480 points)
Thanks Fiona.  That's great information.
0 votes

James,

 

The regulator for drilling off the coast of Newfoundland (C-NLOPB) provides guidance in the form of the Drilling and Production Guidelines (March 31, 2011) which can be found at the following web address:  http://www.cnlopb.ca/pdfs/guidelines/drill_prod_guide.pdf

 

When investigating procedures for well decommissioning, Husky’s primary objective is to observe the regulations and guidelines of the C-NLOPB, more specifically Part 6 of the “Drilling and Production Guidelines”.  As a secondary objective, the requirements of NORSOK D-010 and the recommendations of Oil & Gas UK (http://oilandgasuk.co.uk/) are evaluated and observed where practicable.

Reservoir Isolation

With respect to different reservoir sections within a well, the C-NLOPB does not provide much guidance.  The regulator simply states the following:

56     Suspension or Abandonment

 

The operator shall ensure that every well that is suspended or abandoned can be readily located and left in a condition that

 

a)  Provides for isolation of all hydrocarbon bearing zones and discrete pressures zones

b)  Prevents any formation fluid from flowing through or escaping from the well-bore.

 

 

Per NORSOK D-010, Section 9.6.2, assuming that the reservoir sections are in the same “pressure regime” they can be abandoned with a primary/secondary plug set above the uppermost formation fluid-bearing section – see figure below. 

 

 

Cement Plug Length

NORSOK indicates that a 100m (330ft) cement plug is sufficient as a combination barrier solution when cement bond logs are not available for  well – this requirement exceeds those of the CNLOPB (60m if set within casing). 

The O&G UK Guidelines for the Suspension and Abandonment of Wells recommends 240m (800ft) to serve as a combination barrier solution – see barrier diagram below.  The guideline specifies “good cement” in the annulus which implies that cement bond logs are available. 

Verification of Barriers

NORSOK D-010 states that tagging a cement plug is a required method of verification even when pumped on top of pressure tested mechanical plug. 

The recommendations of the O&G UK Guidelines for the Suspension and Abandonment of Wells vary from NORSOK stating the following:

The C-NLOPB is aligned with the O&G UK Guidelines, stating the following in the “Drilling and Production Guidelines”, Section 59.4, m):

 

Any cement plug that is not supported by a bridge plug (or the bottom of the well) should be confirmed to be in place by either tagging the plug or by using some other appropriate means to confirm the presence of the plug.

 

 

Cutting Casing

With respect to the intermediate casing, the CNLOPB, “Drilling and Production Guidelines”, Section 59.4, i) requires that the stump of any cut and recovered casing strings be plugged with cement.  

Hope this helps!

Matt Dicks

Completions Engineer, Husky Energy

answered Apr 27, 2016 by Matt Dicks (140 points)
edited Apr 27, 2016 by Matt Dicks
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