Mud Storage and Tanks and Reserve Pit Overview – VDO Training

Mud storage and tanks / reserved pits are one of the critical rig equipment. It must provide enough volume for drilling operation. It sounds simple however personnel must really understand about it otherwise it will affect the overall operation. Today, we would like to share this excellent vdo training in the topic of  “Mud Storage and Tanks and Reserve Pit Overview” and the full VDO transcripts is provided to help someone gets full understanding on this subject. We wish you would enjoy this topic.

Full VDO Transcript


Mud is made up at the Rig location.  Most Rigs have several steel Mud Tanks. Muds and additives are mixed and held in the tanks. Some land Rigs also have a Reserved Pit dug out of the ground. Mud tanks are also called Mud Pits, a carry-over from the days of earthen pits. Mud Tank is the preferred term. The Rig does not necessarily use all the Mud Tanks at once although it does use several. The Active Tanks hold mud the pump actively circulates. Often mud components come to the Rig in sacs.

Normally the crew stores the sacs in a special component called the Mud House or Sac Room. The house or room keeps the sacs dry and allows them to be stored with care. These silo like tanks are bulk tanks or P tanks. They hold mud additive like Barite and Bentonite. Crew members use some additives in such large quantities that suppliers load them into the bulk tanks to save time and money. Bulk tanks usually have their own Hopper or Pneumatic system for transferring the additives to the mud system. The pump takes the mud out of the active mud tanks and circulates it through the system. Crew members connect the mud tanks with the piping and manifolds.

The number of active mud tanks depends on the amount of mud needed to keep the hole full. And the volume required on the surface to keep the mud in good condition for circulating.  The Sand Trap is the tank directly below the Shale Shaker.  The Shale Shaker removes most of the cuttings from the mud. But some are so small the Shaker cannot trap them, these fall into the Sand Trap. The Sand Trap is the first Settling Tank. Crew members have to clean it regularly to remove the built-up solids. Some small or old Rigs may have two or more Settling Tanks in the tank system. They allow solids in the mud to settle out but settling tanks do not do a very good job as compared with newer generation solids removal equipment so today most Rigs use a de-sander and de-silter.  Reserve Tanks are not a part of the active mud tank system. Instead the crew uses them to hold excess mud. Or they may use them to hold a different type of mud than the pump is currently circulating.  They may also store heavy mud for emergency well control operations.

A Slug Tank is a relatively small separate tank or it may be small separate part of a larger tank. The crew uses the Slug Tank to mix the slug. A slug is a small amount of a heavy mud that is pumped down the String. Crew members may also use a slug tank to mix a small amount of mud for a special purpose. For example the driller may need place or spot a small quantity of high viscosity mud also called a Pill at some point downhole. The Suction Tank is where the mud pump picks up mud ready to circulate downhole. Mud in the Suction Tank should be clean, free of solids and gas and be properly formulated or conditioned. Crew members use the Chemical Tank to mix special chemicals such as Caustic that they will put into the Active Mud Tank.

On some land Rigs, the Rig owner digs a large pit next to the Rig. This pit is called the Reserve Pit. The crew puts waste mud and the run-off from the work site in the Reserve Pit. In an emergency they can also use it as a place to put more mud than the tanks can hold. Often the Rig operator lines the Reserve Pit with a thick plastic sheet to prevent Liquids from leaching into the soil. And if the Rig is on a migratory bird fly way the operator covers it with netting to keep the water fowl from landing in it. Land Rigs drilling in environmentally sensitive areas will not have a Reserve Pit. Instead waste and run-off or hulled to an approved waste disposal area.

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