We are testing a cased well with complete Schlumberger DST Assy and dealing with the following situation:
- Casing 7” @ 4130m
- Liner 5” @5000m
- Liner hanger inside 7” casing @4000
- Perforations 4945 - 4890m
The testing string (from the bottom):
- 2â…œ” tubing as tail below packer @4800m
- Packer inside 7” csg @ 4000m (just above 5” hanger)
- 2⅞” tubing from DST Assy to surface.
Fluids during testing:
- Formation fluid = gas + condensate
- Formation pressure = 600 bar.
I´m asking to help me for killing procedure since even with ”œbull heading procedure”, below the packer, there is a volume of 5m3 of gas in the annulus between 2â…œ” tbg and 5” liner pressurized at 600 bars.
Any help, recommendations or comments will be much appreciated.
If I remember sometime in 1999 when I was working for Petrom Exploration Mediterranean Inc. in Turkey we were partners with Perenco (Turkey) for some exploration blocks.
We haven´t jet ran the DST string which means as I´ve answered to John, I will try to find if the service company has a classic circulation valve to be opened and closed with slick line to be placed just below the packer.
Many thanks for your solution - with ported sub or perforated joint just below the packer, circulation to the string end will be impossible. Probably a circulation vale opened with slick line can solve the problem - open it for bull heading and close it for circulation.
Again many thanks
I agree with John. The possibility to bullhead through any communication devise right below the packer seems optimal.
However, if this is not achievable due to absence of proper equipment or if the string is already being run, then not too many factor can stop you from punching or perforating the 2 7/8" tubing below the packer before you go for well killing. Having such communication will ensure that your 800 m of gas in the tailpipe annulus will be bullheaded too.
You have 2 options: Push the gas back in (bullhead) or circulate it out.
I go for bull-heading because it's simpler and faster. However, confirm your MAASP is not exceeded with the anticipated bullheading pressures.
Consider displacing above packer to a suitably weighted fluid that can compensate for the loss in hydrostatic due to the gas column. Close the annular, release packer and bullhead (over-displace) via the kill line while monitoring pressures at surface.
The other option is to release packer and circulate out while maintaining constant bottom hole pressure a la well control...
If you place a ported sub or perforated pup immediately below your packer, any gas in the annular area between tailpipe and liner will be pushed into the formation when you bullhead below the packer.