STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

838 Drilling and Well Completions
Ap, = [( (1.6)(468.42) (3)(0.729)+1
3.826 )( (4NO.729)
= 94.32 psi
(0.43)( 5000)
(300)( 3.826)
Flow inside the drill collars
It is easy to check that the flow is turbulent and thus Equation 4-114 is chosen
to calculate the pressure loss Ap2.
AP2 =
(7.7 x 10~5)(100~8)(27)0~2(280)'~8(500) = 243.23psi
(2. 25)4.8
Annulus flow around the drill collars
To calculate the critical velocity, Equation 4-1 11 was used
] I/(% 0.729) [
2.4 (2)(0.729)+1] 0.721y(2-0.729)
(3.878)( lo4 )(O. 433)
vc=[ 10 8.5 -6.75 (3)(0.729)
= 441.79ftJmin = 7.36ftJs
Since v < vc, the flow is laminar and Equation 4-109 is chosen to calculate
the pressure loss Ap,.
[(2.4)(25.92)(2)(0.729)+ 1
*" = (8.5-6.75) (3)(0.729)
= 32.27 psi
10.729
(0.433)500
(300)(8.5- 6.75)
Annulus flow around the drill pipe in the open hole section
It is found from Equation 4-111 that the flow is laminar, thus Equation 4109
can be used
[ (2.4)( 131.87) (2)(0.729) + 1
= (8.5 - 4.5) (3)(0.729)
= 9.51 psi
0.729
(0.433)lOOO
(300)(8.5 - 4.5)
Annulus flow around the drill pipe in a cased section
It is found from Equation 4-111 that the flow is laminar, thus Equation 4-109
can be used.