Drilling fluids recycling systems have found favor with the mid-size rig contractors and are even being used with some mini-rigs today, Arlin Fletcher explains.
Although utilized by an elite group of river crossing contractors just a few years ago, drilling fluids recycling systems have found favor with the mid-size rig contractors and are even being used with some mini-rigs today. Advantages such as cleaner locations, less water hauled in and less mud hauled off, less drilling fluid products required to complete the bore, and reduction in labor cost and drilling time are now being had by contractors throughout the industry. Just as special care is taken in selection of drilling rigs, drill stem, bits and reamers, the same care should be taken in selecting a system and training operators.
Advantages and Disadvantages of Hydrocyclone Underflow Recovery
Although hydrocyclones are capable of removing very fine solids (four-inch cones make a cut point of around 15 microns; five-inch cones make a cut point of around 20 to 25 microns), the discharge is a slurry that can consist of up to 15 percent of total liquid processed. The advantage to discarding this slurry is in removing more ultra fine solids. The disadvantage is large amounts of waste to dispose of. Lots of drilling contractors will try to get around this by discharging slurry back into the spoils pit. The problem with this practice is as the solids content of the spoils pit increases, efficiency of the hydrocyclones decreases and more solids are returned to the rig's mud pump.