## Volume height and pressure gained because of slug

a) Volume gained in mud pits after slug is pumped, due to U-tubing: Vol, bbl = ft of dry pipe x drill pipe capacity, bbl/ft b) Height, ft, that the slug would occupy in annulus: Height, ft = annulus vol, ft/bbl x slug vol, bbl c) Hydrostatic pressure gained in annulus because of slug:

HP si - sluS x difference in gradient, psi/ft

'pS1 in annulus, ft between slug wt and mud wt

Example: Feet of dry pipe (2 stands) = 184 ft

Slug volume = 32.4bbl

Slug weight = 13.2ppg

Mud weight = 12.2 ppg

Drill pipe capacity = 0.01422 bbl/ft

Annulus volume (8-1/2in. by 4-l/2in.) = 19.8ft/bbl a) Volume gained in mud pits after slug is pumped due to U-tubing:

Vol, bbl = 184ft x 0.01422bbl/ft Vol = 2.62 bbl b) Height, ft, that the slug would occupy in the annulus:

Height, ft = 19.8ft/bbl x 32.4bbl Height = 641.5 ft c) Hydrostatic pressure gained in annulus because of slug:

HP, psi = 641.5ft (13.2 - 12.2) x 0.05: HP, psi = 641.5 ft x 0.052 HP = 3 3.4 psi 