"In the bulk mixing system used during the trial, base fluids were combined with dry chemicals at the rig in a closed, dust-free mixing vessel. Using mixing technology adapted from other industries, a high-volume, high-shear mixer was used to produce rapid and efficient preparation of drilling fluids on the rig. For mixing polymers, the system additionally uses a high-volume, high-shear in-line pump in tandem with the main mixer vessel. The mixer is very versatile and can accept materials from bulk bags, the rig's bulk barite supply (via a pneumatic line), polymer tanks or liquid additive tote tanks. The mixer also has an auxiliary hopper to accommodate product that is used in small quantities or is unavailable in bulk form. After mixing, the finished drilling fluid was sent through various output lines either to the active mud pit, to the cementing unit, directly to the suction line downhole, or into auxiliary mud pits."
"Bulk mixing furthermore enables significant timesavings.
Using conventional hopper systems, barite is typically mixed
at the rate of 200 to 300 sacks per hour. Actual performance
by the mixing system over a period of several months has
shown that barite can be mixed at the rate of 50 sacks per
minute = 3000 sacks per hour (i.e., a ten-fold mixing rate
increase). Similar improvements have been observed for
mixing bulk gel / bentonite. Furthermore, one rig hand cutting sacks can normally achieve a rate of 40 to 50 sacks per hour.
By comparison, a single bulk mixer operator using bulk bags
can mix 2000 lbs. of material in 5 to 10 minutes (i.e., 5 times faster). Such improved efficiencies translate into considerable timesavings."
