The following planning guidelines shall be adhered to:
- The casing tally (bottoms up) shall be made listing the pipe as when racked. Casing length shall be casing running length and not total length.
- The casing tally shall be checked by multiplying the number of joints to be run in the hole by the average length of 20 joints selected at random. Any significant difference in the resulting calculation of the casing setting depth indicates and error which shall be resolved prior to running the casing.
- Casing shall be drifted after it is racked with the correct size of API drift. Any failures to be clearly marked. The drift mandrel dimension shall confirm the API RP 5A5,
- 13.3/8in casing and smaller: mandrel length 12in
- 9.5/8in casing and smaller: mandrel length 12in
- tubing (all sizes): mandrel length 12in
- After the casing has been measured and drifted, the pin and box ends shall be doped (modified dope - slip factor one) and the thread protectors replaced. The protectors shall be hand tight.
- The hole depth shall be checked by strapping out (measuring) of the hole at least once prior to reaching the casing point. If the measurements do not agree the pipe shall be re-measured.
- A ‘slip type’ casing hanger shall be used if the casing cannot be set on bottom. Three casing joints shall be checked for ovality and set aside to be run at the top of the string if required.
- Both shoe and collar joint shall be fitted with a blanked off casing protector as soon as the shoe/collar have been installed to prevent debris entering during storage/handling.
- Check all wellhead equipment to be used on the casing installation is as per the Drilling Programme.
- The placement of shoe and collar, and special casing equipment shall be confirmed. All collars shall arrive at the wellsite made up and threadlocked. Float equipment shall be pre-bucked onto the pin end of a casing joint to facilitate entry of a spear in the event of fishing. Verification of drifting make-up torque and unique ID to be painted on joints.
- When threadlocking is necessary on the rig floor, care shall be taken to ensure that both pin and box are clean and dry. The thread lock compound shall only be placed on the pin of the connection with the joint pulled to one side so that nothing can fall into the hole.
- All accessories shall be made up on casing pin ends to ease fishing operations in case the casing should fall into the hole.
- Prior to pulling out of the hole for casing, the Mud Engineer shall check and verify that the mud is in good condition and report this to the Drilling Supervisor.
- Where tank capacity allows, displacement fluid shall be pumped from and received into separate tanks. This provides a positive method of measuring losses and displacement volumes.
- Each joint of casing on the rack shall be visually inspected inside to ensure all joints are clear of foreign matter.
- A hollow rabbit shall be dropped before the last trip out of the hole prior to running casing or liner with a drillpipe running string. The rabbit shall be equipped with a wireline fishing neck.
- On returning casing to the supply base all joints should be protected, therefore, keep sufficient pin and box protectors for the estimated return load. Any damaged joints should be clearly marked with red paint and manifested separately. Any joints failing to drift should be clearly marked ‘ NO DRIFT’ in red paint and manifested separately.
- Ensure that a full opening valve (lower kelly cock or similar) made up to a casing crossover is held on the rig floor.
- Ensure that the upper pipe rams are dressed with the correctly sized casing rams and the bonnet seals tested to the stack test pressure, unless a specific dispensation is issued by the Drilling Manager.
Casing and Liner Conditio
Casing/liner threads must be free of any damage which could:
- affect the seal and therefore the pressure rating of the string.
- reduce their collapse or burst ratings and ultimately their overall life expectancy.
Pressure Tests, Calculations and Running Measurements
In order to maintain the integrity of the casing/liner and wellhead, the casing/liner pressure test ratings must not be exceeded.
Errors in casing/liner calculations and running measurements, which could lead to incorrect shoe depth, must be avoided.