Piranha Mill with Mud Motor Mills 9 5/8-in Casing from 363.11 m to 819 m Offshore Brunei | Schlumberger
Tech Report
Location
Brunei, Asia
Details
Operator
Brunei Shell Petroleum

Lithology
Subsea salt

Environment
Deep water

Casing size
13 5/8 in

Casing weight
88.2 lbm/ft

Casing grade
Q125

Average ROP
2–3 m/h at the casing body 0.5–1.0 m/h through the casing collar

Speed
158–250 rpm

WOB
1,000–17,000 lbm

Flow rate
600–1,150 galUS/min

Standpipe pressure
409–1,450 psi

Torque
1,000–1,500 ft.lbm
Background
The operator needed to mill 95/8-in casing deep enough for an 185/8-in casing exit offshore Brunei.
Products Used

Piranha Mill with Mud Motor Mills 9 5/8-in Casing from 363.11 m to 819 m Offshore Brunei

Using a string stabilizer above the drillpipe increases the amount of swarf to surface in deep water

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A total of 455.89 m of casing was milled at an average milling ROP of 2-3 m/h at the casing body and 0.5-1.0 m/h through the casing collars. A 17 1/4-in string stabilizer was used above the Hevi-Wate transition drillpipe to stir and prevent the metal swarf from bird nesting at the wellhead area due to a change in cross-sectional area. The amount of metal swarf that came to surface increased proportionally to the flow rate.
Products Used

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