How to avoid casing collapse during inner string cementing
This article reports that in the Mobile Bay area offshore Alabama, inflatable surface packoffs are being used to seal the top of the 20-in. conductor casing-to-drill pipe annulus. With the seal in place, annular pressure is maintained during inner string cementing jobs to counter forces that tend to shorten the drill pipe inner string. Inside pressure also helps protect the casing from collapse due to the hydrostatic pressure of a long column of cement. Casing is less resistant than the bottom of the hole and the wellbore, (unless a weak formation breaks down) and can crush under the hydrostatic weight when fluid inside does not offer enough offsetting support. Casing collapse can cause cement to leak into the casing-to-drill pipe annulus, thereby cementing the drill string in the well or otherwise ruining the cement job. In a situation where casing does not have sufficient collapse resistance to withstand hydrostatic pressure loading, a surface packoff can be used to maintain pressure inside the casing throughout the cementing job.
- Research Organization:
- Halliburton Services, Duncan, OK
- OSTI ID:
- 5968187
- Journal Information:
- Drilling-DCW; (United States), Vol. 48:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
03 NATURAL GAS
42 ENGINEERING
GULF OF MEXICO
OFFSHORE PLATFORMS
WELL CASINGS
ACCIDENTS
CEMENTING
ALABAMA
CEMENTS
DRILL PIPES
FAILURES
HYDROSTATICS
LEAKS
NATURAL GAS WELLS
OIL WELLS
PRESSURE DEPENDENCE
SEALS
WELL COMPLETION
ATLANTIC OCEAN
BUILDING MATERIALS
CARIBBEAN SEA
DRILLING EQUIPMENT
EQUIPMENT
FEDERAL REGION IV
MATERIALS
NORTH AMERICA
PIPES
SEAS
SURFACE WATERS
USA
WELLS
020300* - Petroleum- Drilling & Production
030300 - Natural Gas- Drilling
Production
& Processing
420206 - Engineering- Mining & Drilling Equipment & Facilities- (1980-1989)
422000 - Engineering- Mining & Underground Engineering- (1980-)