The first actions taken when the drillstring becomes stuck have a great influence on the chance of success. The information detailed belowl give guidance to the correct early response when the pipe becomes stuck.

Effective Pull On Stuck Pipe

When determining the pull on differentially or mechanically stuck drillpipe, the actual weight of the string in air is to be used and not the indicated weight as recorded by the weight indicator.

For example:

Depth

 

10,000 ft

Weight of drill collars in air

743 ft of 6-1/2” OD x 3” ID @ 89 lb/ft

66,127 lb

Weight of DP in air

9,257 ft x 19.50 lb/ft

180,512 lb

Total weight of string in air

 

246,639 lb

 

 

 

Weight indicator reading

 

220,000 lb

Weight of top drive, hook, blocks, swivel, etc.

 

50,000 lb

Pull reported at 100,000 lbs. over indicator reading

 

320,000 lb

Less hook, block, swivel, etc.

 

- 50,000 lb

Effective pull on string

 

270,000 lb

 

 

 

Assuming that pipe is stuck on bottom, then the effective pull at the stuck point = 270,000 - 246,639 (no buoyancy of pipe)

 

23,361 lb

In order to apply a pull of 100,000 lbs. at the bit, the Indicator reading would have to be 246,639 + 50,000 + 100,000 lb

 

396,639 lb

 

 

 

This would mean that the pull on the pipe amounts to

(396,639 lb - 50,000 lb)

 

346,639 lb