Page 429 - Air and Gas Drilling Manual

Chapter 9: Aerated Fluid Drilling 9-33
The calculation sequence for this illustrative example is divided into five depth
increments. The increments start at the top of the borehole with the first increment
at the top and the fifth increment at the bottom.
The total length of the lumped drill pipe body increment (first), H 1, in the cased
section of the borehole is
7 000
,
,
H 1 7 000 1 5 .
30
H 1 6 650 ft
,
The inside diameter of the casing along this length of the cased section of the
borehole is
.
d 8 017 inches
1
d 1
D 1
12
.
D 0 668 ft
1
and the outside diameter of the drill pipe body along this length is
d 2 450 inches
.
d 2
D
2
12
D 2 0 375 ft
.
The total length of the lumped drill pipe tool joints increment (second), H 2, in
the cased section of the borehole is

7 000
,
H 2 15 .
30
H 350 ft
2
The inside diameter of the casing along this length of the cased section of the
borehole is
D 1 0 668 ft
.
and the outside diameter of the drill pipe tool joints along this length is