BAKER HUGHES - Drilling Fluids Reference Manual

Water Based Drilling Fluids
polymer. Performance and desirable results should be the determining factors in establishing the
value of a product or a fluid system.
Baker Hughes Drilling Fluids uses potassium in its NEW-DRILL system, especially in the
tectonically stressed shale encountered in the foothills of the Canadian Rockies. NEW-DRILL is
believed to adsorb on the positive charged edges of exposed clays, reducing the water sensitivity
of the clay formations and contributing to increased inhibition. The potassium ion is also
absorbed on to the clay structure causing it to take on the characteristics of illite. This action
results in the loss of polymer as well as a decrease in potassium ion concentrations as solids are
discharged, thus requiring constant monitoring of the concentrations of each and replenishing
them as needed.
Mixing Procedure for NEW-DRILL System with KCl
Add desired KCl concentration to water in the active system (see Chapter 16, Engineering Data).
Normally 10 to 17.0 lbm/bbl meets inhibition requirements.
Pre-hydrate MILGEL in premix tank (approximately 30 lbm/bbl) and add pre-hydrated MILGEL
slowly (1 in. to 1½ in. stream) to KCl solution to obtain desired viscosity. Normally 6 to 8
lbm/bbl of pre-hydrated bentonite in the KCl solution is adequate. Additional KCl will be
required to offset the fresh water added to the system in the form of pre-hydrated bentonite.
Note: On initial make up, where large volumes are needed for displacement, the active system
can be filled with fresh water and the bentonite added first and pre-hydrated and then followed by
KCl.
Adjust pH to approximately 9 - 10 with caustic soda or KOH.
Add ½ to l.0 lbm/bbl of XAN-PLEX ® D slowly.
Add ¼ to ½ lbm/bbl NEW-DRILL ® .
For additional filtration control. Use MILSTARCH or BIO-LOSE and MIL-PAC in a 2:1 ratio. If
MIL-PAC is used, add very slowly (1/8 to ¼ lbm/bbl over a 6 to 8 hour interval) and monitor
rheological properties.
Maintenance
1. Monitor potassium ion (see Fluid Testing Procedures Manual) to maintain the desired
concentration.
2. If desirable, pre-hydrate bentonite in premix tank. Add sufficient potassium material to
compensate for water additions. A water meter is recommended to determine dilution
volumes.
3. Solids control equipment (desander, desilter, and fine screen shakers, plus a centrifuge for
weighted systems) should be considered absolute necessities with this system.
4. Control pH in the 8.5 to 10.0 range with caustic soda. Corrosion rates can be reduced with
oxygen scavengers such as NOXYGEN TM .
5. Keep entrained air out of the system by:
• Shutting the mud hopper down when it is not in use
• Submerging mud guns to prevent aeration
• Judicious use of hydrocyclones
Reference Manual
Baker Hughes Drilling Fluids
3-52 Revised 2006