# A drill string is composed of 9000 ft of 5-in 19.5-lbm/ft drill pipe and 1000 ft of drill collars...

## Question:

A drill string is composed of 9000 ft of 5-in OD, 19.5-lbm/ft drill pipe and 1000 ft of drill collars having a 3.0-in. ID. Calculate the loss in fluid level in the well if 10 stands of drill pipe are pulled without filling the hole. The ID of the casing in the hole is 10.05 in.

Drill String are long, hollow circular section with thick wall use to transmit torque to the drill bit attached at one end of the drill string stand. The hollow internal section is used to supply drilling mud (a high density fluid) to the bottom of the hole being drilled and collected back through the annular gap between the drilled hole and the drill string. These stands or pipes are connected together using the drill collar usually welded at one end of the drill pipe. The length of the drill string stand is typically standardized to 31.6 ft (9.6 m) per stand.

Assuming that the standardized size of the drillstrings are adopted for the drilling work, the decrease in length (L) with the removal of 10 stands...

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