BAKER HUGHES - Drilling Fluids Reference Manual

PRESSURE PREDICTION AND CONTROL
2. Determine how many feet of barite plug in the open hole are desired.
3. Calculate the bbl of slurry and sacks of barite required, and add an extra 10 bbl.
4. Mix the slurry and pump it into the drillpipe.
5. Displace the slurry so that the height of the barite plug in the drillpipe is 2 bbl
higher than the top of the barite plug in the annulus.
6. Break connections and pull up immediately above the plug. If possible, circulate on
top of the plug.
7. If possible, circulate for several hours.
Barite settling is inherently slow and often the results are unpredictable. Failure rates for barite
plugs increase when hydrostatic kill conditions are not maintained.
Table 12-5 gives the materials and procedures necessary for mixing a barite plug for an oilbase
fluid.
Materials
Diesel Oil
CARBO-MUL ®
OMNI-COTE ®
MIL-BAR ®
Quantities
24.6 gal
0.5 gal
0.5 gal
576 lb
Table 12 - 5 Barite Plugs for Oil-Base Fluids (1 bbl of 18.0 lb m /gal Slurry)
Procedure for Preparing Barite Plug for Oil-Base Fluid
1. Clear all lines that will be used to pump the plug of water or water wet materials.
This may require flushing the lines with diesel oil.
2. To the appropriate amount of diesel oil, add the required CARBO-MUL ® HT and
OMNI-COTE ® simultaneously and mix for 10 minutes.
3. Mix the required MIL-BAR ® with the diesel/CARBO-MUL HT/ OMNI-COTE
mixture and displace continuously into the hole with the pumping unit
Note:
Any base fluid may be substituted for the diesel oil, but the formulation
must be adjusted to account for the base fluid density.
Spot the diesel oil/barite plug in the same manner as a water-base plug.
Barite Plug Example
• Open hole = 8.5 in.
• Height of barite plug desired = 500 ft
• Weight of slurry desired = 18.0 lb m /gal
⎛ 8.5
2
Volume of Barite Slurry = ⎟ ⎞
⎜ x 500 ft = 35 bbl
⎝1029.4
⎠
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 12-36