Inner String (Stinger) Casing Cementation Procedure

For offshore cementation of the 20in surface conductor, the following procedures shall be used for inner string cementation:

1. Make up stab-in sub and centraliser and rih on 5in drillpipe.
2. Stab stinger into the float shoe and engage the cementing tool to the casing head housing. Fill drillpipe and check for any returns from inside casing or a drop in level.
3. Pressure test casing. if the test fails, take appropriate action as detailed below:

case 1

Stinger seals are leaking, identified by:

1. with cement stinger - returns by circulating through annulus.
2. with test port - returns  by circulating through stinger.

Pull one joint and perform poor-boy cement job using a pack-off at the wellhead. ensure that the test port on the cementing tool is closed.

case 2

Stinger seals have full integrity, identified by:

checking for returns through the stinger. check for returns through the casing/stinger annulus when circulating conventionally through the stinger.

assess severity of the leak, inform drd/dro who will advise either a) continue or b) pull casing and check for leaks.

4. Establish circulation carefully and make at least one full circulation. monitor closely for losses and adjust flow rate as necessary. returns will be at seabed.
5. Pre-mix and re-circulate slurry until gradient is within safe tolerance.
6. Mix and pump slurry as per programme.
7. Pump the calculated volume plus 20% excess if the well is not to be cemented to surface. if the well is to be cemented back to surface, continue pumping until returns are observed at the wellhead/mudline, or until 200 % of the theoretical volume has been pumped, whichever comes first. in the latter case, if returns have not been observed, check for losses and contact base. divers to confirm cement at seabed.
8. displace dp with water (2 bbl under displaced)
9. Check for backflow. if there is no backflow, pull stinger back
   50 ft, circulate clean and pooh with stinger. if backflow is observed, displace cement from the drillpipe and maintain pressure.
10. woc, slack off and back off landing joint. Install chhs.
11. rih 2” stinger in 20” casing/ 26” hole annulus. confirm top of cement. if toc > 10ft from seabed conduct top fill job.