Private Forums
Integrity of DV Collar
24 January 2016
Lectori Salutem,
I was wondering if the members of the forum could share their opinion on whether a DV collar is viewed as a potential leak path or not - assuming it is successfully employed (no problems opening / closing and positive pressure test).
Also, does anyone have access to track record of failures or success of DV collars.
It would also be interesting to hear what your companies policy or standard is if a DV collar is used in a production casing string. Does your policy / standard require the DV collar to be covered by the liner lap?
Many thanks in advance,
Harald Benning
9 answer(s)
PaulHowlett
CEO
Sudelac
Total Posts: 90
Join Date: 10/04/08
All, an interesting set of replies to Harald on the use of stage collars/DV, some suggesting that they are providing a V0 rated stage collar. I was wondering if there is an API standard for specifically testing stage collars to VO like there is for float equipment (API 10F). I don't think there is, and if it was to exist it would likely entail a fairly stringent set of pre-use function pressure tests, flow during tests, temperature soak tests, closing tests and post-close pressure tests at temperate to simulate the ports opening, being pump through extensively then closing and sealing. If the vendors who claim V0 are simply putting a newly manufactured stage collar into the closed position then performing a V0 test on it loosely based around the V0 for Bridge Plugs then I would suggest this does not mean that a "used" stage collar will be V0. The operators may wish to consider having their stage collar supplier perform a test very close to API 10F on the stage collar assuming the ports and closing sleeve are akin to the poppet valve, then perform a V0 leak test, this may prove more valid. If there is a API RP or Specification for Stage Collars that includes V0 style testing can someone reference it to me? Paul
Harald
Drilling Supt
Amni Int'l PetDevCo
Total Posts: 24
Join Date: 13/09/07
Esteemed members of the forum,
Many thanks for your time and efforts to provide me with answers to my query regarding integrity of DV collars. This has been most helpful.
The next step for us is to subject this to a robust risk assessment using the data provided.
Best regards,
Harald.
neilanderson52
Business development Manager
Archer - The well company
Total Posts: 1
Join Date: 24/03/15
Harald, technology has moved forward as with everything else.  The Archer Cflex collar is V0 rated with a selection of seals avaiable to suite your environment, such as FFKM, for H2s and non-elastomeric seals for hot / harsh environments.  Also with perminant lock features. Your local Archer rep can descuss in more detail if you want to get in touch.

Regards

Neil
JeremyMazzilli
Region Product Line Manager
Weatherford
Total Posts: 3
Join Date: 12/10/14

Hi Harald, 

This is a very good question and exactly aligned with what Weatherford Cementing Product is providing. Now that the technology has evolved so much I would say it depend on the type of DV tool you are looking for, the environment and the purpose.

Please may I also suggest you to have a look at the ISO 14998 V0 criteria.

http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=55308

If you contact your local Weatherford rep, I'm positive that he will be more than happy to answer your questions, share with you track records, share experiences and help you resolve your issues.  

Please let me know if there is anything else we can help you with.  

Regards, 

Jeremy

Scott_McNeil
Consultant
SPREADAssociates
Total Posts: 110
Join Date: 05/03/08
Harald,

None of the Companies (admittedly none of them 'Majors') I have worked for recently have had a policy on Stage Collar use or testing.

While the design has improved in the last few years with the introduction of metal-to-metal seals, mechanically they are still not as reliable as you would hope.

I have had several failures, not always due to the Stage Collar itself failing, but because if you are having to use a Stage Collar, that usually means there are other issues you are dealing with which can lead to an overall failure of the job.

My philosophy has been that if mechanically the job goes well, it pressure tests O.K., it's an intermediate string and the pressure regime in the next section is higher - then that is acceptable.

However, if it's in a production string, or you need to drop the mud weight in the next hole section, I would certainly advocate inflow testing - I've had two Stage Collars pass the pressure test, but leaked on the inflow test.

Also, I would also advocate the use of a combination packer/collar to increase the chances of success of the 2nd stage.

Best Regards

Scott
Augusto
Consultant [retired Shell staff]
SPREADAssociates
Total Posts: 245
Join Date: 02/09/05
In 1983, I did start my own poorboy drilling equipment performance which was solely based on the drilling reports I actually read.
"DV" collars are top of the list regardless of size or operating area - 26 mishaps!
There were new designs of multistage cementing collars which were marginally better, but my experience does not recommend them. Bottom line: they leak!
So having an unreliable elastomeric seal into a production string does not seem wise...


PatricioLuppi
Senior Drilling Engineer
TOTAL
Total Posts: 3
Join Date: 19/02/09

You can also check the Archer Cflex port collar, probably similar to the tam one. They have documentation on qualification as per ISO 14310 VO, NORSOK M-710 (ageing), NACE MR-0175 and others.

Agree they have not traditionally been used exposed to production or long term service, but technology might be catching up...

Companyrep
Drilling Specialist/Well Engineer/Training Consultant
Kingdom Drilling
Total Posts: 360
Join Date: 10/01/05

I suggest you contact  TAM North Sea's Aberdeen office.

They can assist in providing you with some facts and figures to the new state of the art port collars, with metal to metal seals that are being run today world-wide.

or others who have similar product in their inventory.


regards,


Peter.
RuariTruter
SPREADAssociates
Total Posts: 18
Join Date: 17/09/07

Harald

I've checked but from both memory & copies, I cannot find a direct reference to a DV collar in a Barrier Policy (Of a Co that I've worked with).

 My experience has always been that it needs to be covered up/put behind pipe at some stage before the well goes into service, even if it tests.  Be that the next string or a liner lap.   Basically you can drill ahead with a tested DV but not produce.

Hearsay gives a historically high rate of failure, and a perception that you are one o-ring away from failure.

In a production string - In the right circumstances (Well Pressure, location, quality product, track record), I could be persuaded by a decent assessment of the risks and the appropriate checks/outcomes on installation.

For example, it's a metal-metal seal with an o-ring BU, it has 500' of confirmed cmt above and a decent shoe below, it is tested to heck (Extra time?  Inflow test?), only see's reservoir pressure not gas lift.  You get the idea.

My one concern would be  - what if it doesn't test - what then?

Cheers

Ruari



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