Our Petroleum Technologist wants to run 4-1/2” tubing instead of 3-1/2”. The problem is a 4-1/2”, 10kpsi TRSCSSSV will not fit in the already-installed 7” casing. He has suggested we run 4-1/2” tubing from surface and crossover to 3-1/2” just above the packer at 4,500mTVD. This would allow us to run a 3-1/2” TRSCSSSV at 4,500mTVD. My concerns are;-
1) Do TRSCSSSVs work on the end of a 4,500m control line?
2) Are the closing / opening times much longer?
3) Is this common? I have never heard of anyone setting a TRSCSSSV this deep
4) What is the time to transmit pressure (or bleed-off pressure) along 4,500m of control line
Your comments and thoughts on this would be most appreciated, especially from anyone who has addressed and overcome this challenge.
1 You could check with your SSSV provider, but you may be able to do it with a balance line system. A normal single line SSSV would not work as the hydro-static head of the control line fluid would maintain the flapper permanently open.
2 Yes, just because of the volume of the control lines.
3 The deepest I have ever run one is ca 2,500 ft in a well with high CITHP - potential hydrate issues when shut in.
4 Pass! Would depend on the surface HPU pump.
I would suggest, assuming that equipment below the SSSV allows, that you "bottle-neck", which is something I have done before a couple of times inside 7" casing. 4 1/2" tubing below the tubing hanger, x-over to the 3 1/2" SSSV (at whatever depth is actually recommended) then back to 4 1/2" tubing down to above the packer, where you cross back to the 3 1/2" upper connection on the packer.
As long as there is no need for anything larger than the SSSV ID below, then this should work.