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List the main reasons why do we care about Circulation rate while running liner?
To manage ECD. It's to safeguard against a kick or losses.
At first due to small annular clearance between them, we try to limit the ECD for lost circulation and getting kick. Limit the circulation rate so that to keep shear pin safe and not stuck in between where we don't need to install and inlast for better cement operation.
1- you have to limit circulation rate below the liner hanger setting pressure (shear bolts that release the hanger slips) to avoid shearing and setting the liner hanger accidentally while still RIH. ... (this should be taken care of during planning phase for the liner running & cementing job, .. drilling engineer should give you the maximum alloed circulating pressure, which must be below the minimum setting pressure for the hanger (each bolt shear pressure multiplied by the number of bolts)
- also this circulating pressure should vary along the way while RIH, as the liner goes deeper, you should need higher pressure to circulate thru the liner, so take care, the worst part is at the bottom.
- once the liner at the bottom & the liner hanger is ser, you are free to circulate but take care of the formation fracture pressure as mentioned in point #2.
2- Due to the big OD of the liner (compared to drill pipes), there is a relatively smaller clearance (annulus of liner), and this will give higher ECD than that while drilling. so if you used higher circulating rate, you risk fracturing the formation and having losses and even complete loss.
- of course mud parameters make huge difference in that regard... the highr mud rheology, the highrt the ECD.
3 - to avoid plugging the liner shoe / reamer shoe while RIH.
4- to simulate the pumping rate for the cement job.
5- to ensure liner hanger running tool is still attahced to the liner hanger.
1- Not excceding the liner setting pressure/ searing pins limit.
2- Reduce wash out effect on ball set and paker element.
Limit circulation rate while running in liner keep shear pin safe and not stuck and avoid plugging the liner shoe / reamer shoe while RIH.
more circulation rate will erode the ball seating area and liner can not be get set by hydraulic pressure because ball will not set and fall down from seating area.
To avoid stuck of liner hinger.
1-Prematurely set Hydraulic liner hanger,
2-prematurely release hydraulic running tool,
3- swabbing packer element,
4-wash out the ball seat,
5- breaking the formation/lost circulation.
6- to Simulate the cement pumping rate
for well control and not take any kick
