Marex

Drilling Rig (MODU) Mud Pit Cleaning Systems

The requirement for the carriage and storage of mud on mobile drilling units has increased over the years as the water depth in which a MODU can work has increased. However, it is necessary to remember that the product, drilling mud, still contains the same sort of solids in suspension that it always did. In order to combat the settlement that takes place during storage, mud pits are traditionally fitted with agitators and mud guns. Research that has been carried out into the effectiveness of agitators, has determined that the designs commonly installed in oil rigs are virtually ineffective in use, and the mud guns, connected to low pressure pumping systems available in the pump rooms (apart from the main mud pumps) will do little to clear the bottoms of the pits.

Marex has supplied systems for the cleaning of mud pits, usually including a high pressure pump, with sufficient throughput to operate the machines. If used as recommended by the suppliers, the residues left in the pits when they are emptied will be drastically reduced. In addition, since environmental controls have reduced the opportunities for washing out pits through the dump valves into the sea, any final cleaning with water is minimized and as a result the residues that are discharged into support vessels are limited. These residues, a mixture of mud solids and water, are extremely difficult to displace, and can result in astronomical vessel tank cleaning costs in port.

It is also common for the pits of most mobile units to be at least partially open to the rest of the space in which they are contained, and even those which are initially designed to be totally enclosed, usually have holes cut in the top for the insertion of measuring devices. Hence, Marex has designed a machine which only operates in the downward mode. This machine cleans the bulkheads and the bottom of the tank, but does not jet mud or water into the Mud Pit Room.

Mud pit and mud tank cleaning systems are complex and operators, rig owners or support vessel owners wishing to install them are advised to consult Marex at an early stage.