A variety of systems are available to transport and contain large volumes
of dry bulk chemicals. Commonly known as P-tanks (pressure tanks),
these vessels are usually mounted upright and connected via piping to
a mud mixing hopper. They may also be mounted remote from the hopper and deliver material through a piping system by pneumatic force. Other designs mount the tanks above the hopper and gravity-feed the material. These tanks accommodate most dry bulk chemicals, including barite, bentonite, and cement.
Sack lifting and addition chores on a rig can be hazardous to personnel.
Machines specifically designed to lift pallets and individual bags are now available to reduce or relieve personnel from repetitive motion or back injuries.
Sack-lifting equipment uses large suction cups to grasp individual bags
without harming or deforming them. Suspended overhead, the manually
operated arm permits users to move heavy sacks with ease from pallets
onto mud mixing tables. Floor-mounted sack lifters are also available.
They use either hydraulic or pneumatic pistons to elevate pallets of
sacked material to a comfortable height for transferring onto the hopper
table (Figure 2).
Automated sack handling systems feed individual sacks onto a
conveyor belt, where they are slit, emptied, and compressed. These
systems can be operated manually or programmed for automatic feed at
predetermined levels. Automatic feed regulates addition rates and has
proven to improve fluid properties through accurate dosing rates and
reduced labor costs (Figure 3).
Mud additives are also supplied in big bags (typically 1 m3 or more).
Most large bags are made of durable synthetic fabric with lifting hooks
included for use with overhead cranes. The big bags fit into specifically designed carriages that hold them in place for dispensing out the spout on the bottom (Figure 4). Some models come complete with automated hardware/software packages that regulate addition rates. Manual-control overrides allow operators to directly regulate addition rates. The bags reduce dust generated from sack cutting operations and are collapsible once empty, thus reducing waste volumes and transportation space on boats.