PENG 6002_Sem. 1 2021/2022
20%
Total Duration: 1-1/2 hours for assessment and ½ hour for uploading to Myelearning
a) The density of 1050 bbls of a 15 lbm/gal mud must be increased to 16 lbm/gal. The volume
fraction of low-specific gravity solids also must be reduced from 0.065 to 0.035 by dilution
with water. A final mud volume of 1050 bbls is desired. Compute the volume of original mud
that must be discarded and the amount of water and sacks of API barite that should be added.
Hint: fc2V2 = fc1V1, where f = vol. fraction of low sp. gr. solids and V = vol. of solids
Marks 5
b) Compute the transport ratio, using Moore’s modified correlation, of a 0.375 inch cutting (both
diameter and thickness) having a specific gravity of 2.53 in a 14-lbm/gal mud being pumped
at an annular velocity of 240 gpm in a 6.5 x 3.5 in. annulus. The following data were obtained
for the drilling fluid using a rotational viscometer. Fig 1. Friction Factor vs Particle Reynold’s
Number attached.
Rotor Speed
(rpm)
3
6
100
200
300
600
Dial Reading
(degrees)
4.0
6.6
26.0
44.0
60.0
100.0
Hint: Use Moore’s iterative solution to calculate slip velocity.
Marks 10
c) A 300 ft cement plug is to be placed at a depth of 5000 ft. The open hole size is 8-1/2 in. and
the drill pipe is 3-1/2 in. (13.3 lbm/ft); ID of 2.764 in. Ten barrels of water are to be pumped
ahead of the slurry. Use 25% excess slurry volume and slurry yield of 1.256 cu ft/sks.
i.
ii.
iii.
iv.
v.
Determine volume of cement required.
Number of sacks of cement required
Volume of water to be pumped behind the slurry to balance the plug
Plug length before the pipe is withdrawn
Amount of mud required to spot the plug plus the spacer behind the plug
(Marks 5)
TOTAL – 20%
PENG 6002_Sem. 1 2021/2022
20%
Total Duration: 1-1/2 hours for assessment and ½ hour for uploading to Myelearning
Fig 1.
END OF QUESTION PAPER