STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

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2. S-23-E = 157"
Default: 0110111110 156.796"
Excess: 0110111111 157.148'
Nearest: 01101 11111 157.148"
3. Motor hp at 400 gal/min:
Motor hp at 500 gal/min:
Motor hp at 600 gal/min:
4.
44.8 hp
43.3 hp
38.3 hp
MWD and LWD 947
Table 4-1 26
Typical Conditions Encountered for Various Flowrates
400 gaVmin 500 gaUmin 600 gaUmin Units
Pulse AP motor 100 hp 536 428 357 psi
nozzle AP bit nozzle 460 71 9 1035 psi
closed Total AP 996 1147 1392 psi
AP pulse -200 -200 -200 psi
Pulse AP open 796 947 1192 psi
nozzle Flow pulse nozzle 175 191 21 5 gal
open Flow motodbit 225 309 385 gal
New AP bit 145 274 427 PSI
New AP motor 651 673 765 psi
New hp motor 68 97 138 hP
Example 9: Mud Pulse Telemetry-Pressure
Wave Attenuation
An MWD system is lowered at the end of a 4.5-in. drillstring in an 8-in.
borehole. Neglect the drill collar section of the string. The following data
are available:
total depth: 10,000 ft
borehole average diameter: 8 in.
drillpipe OD: 4.5 in.
drillpipe ID: 3.64 in.
drillpipe Young modulus: 30 x lo6 psi
drillpipe Poisson ratio: 0.3
mud specific weight: 12 lb/gal
mud compressibility: 2.8 x psi-'
mud viscosity: 12 cp
mud flow rate: 400 gal/min
bit nozzles: 3 x $ in.
1. Compute the bottomhole hydrostatic pressure with no flow.
2. Compute the pressure drop in the drill pipe while circulating.
3. Compute the pressure drop in the annulus while circulating.
4. What is the pressure drop in the bit nozzles?
5. What is the pump pressure at surface?
6. Make a graph of the pressure variation with depth without circulation in
the drillpipe and annulus.
7. Compute the velocity of the pressure wave in free mud (not in a drillpipe).