For the calculations the following parameters have been used:
26in and 16in holes: MW 9.3ppg, PV 4, YP 10
12.1/4in and 8.1/2in holes: MW 10 ppg, PV 8, YP 11
9.1/2in drill collars have been used in the 12.1/4in section
For jet selection it has been taken into consideration that lost circulation is frequently occurring and the jet size selection is therefore kept on the high side to allow for pumping of LCM materials at any time. Equally the circulation rates are kept high to obtain enough hydraulic horsepower at the bit to allow for proper hole cleaning.
To avoid frequent pump repair the standpipe pressure is kept around or below 3000 psi. When mud parameters differ from above adjust circulation volume to keep standpipe pressure around 3000 psi.
Example of the output from a Hydraulic Programme.
|
Hole Size (in) |
Depth (ft) |
Volume (gpm) |
Jets (1/32) |
Stp. Pres. (psi) |
HHP/SQin |
|
26 |
600 |
1 200 |
3 x 18 |
2 666 |
2.93 |
|
17.1/2 |
4 000 |
925 |
3 x 17 |
2 963 |
3.7 |
|
17.1/2 |
5 000 |
900 |
3 x 17 |
2 988 |
3.4 |
|
17.1/2 |
6 500 |
875 |
3 x 17 |
2 997 |
3.1 |
|
12.1/4 |
6 500 |
650 |
3 x 14 |
2 922 |
6.2 |
|
12.1/4 |
8 200 |
625 |
3 x 14 |
3 005 |
5.5 |
|
12.1/4 |
10 000 |
600 |
3 x 14 |
2 951 |
4.9 |
|
12.1/4 |
11 500 |
580 |
3 x 14 |
2 907 |
4.4 |
|
12.1/4 |
13 000 |
575 |
3 x 14 |
2 989 |
4.3 |
|
8.1/2 |
10 000 |
325 |
3 x 10 |
2 912 |
6.7 |
|
8.1/2 |
11 500 |
325 |
or |
2 990 |
6.7 |
|
8.1/2 |
13 000 |
325 |
2 x 12 |
3 069 |
6.7 |