M-I SWACO developed the AUTOMATIC TANK CLEANING (ATC) technology to replace slow, laborious and HSE risky manual cleaning. Tanks on rigs and supply vessels must be cleaned as solids build up or fluids changed to avoid cross-contamination. Until now, tank cleaning has typically involved laborers equipped with hoses, pressure washers, shovels and squeegees. The economic and QHSE justifications for the ATC are obvious.
The ATC system improves safety, reduces the number of personnel onboard, while reducing significantly the volume of waste generated. Further, the ATC minimizes downtime during the cleaning process.
The M-I SWACO ATC employs Tank Cleaning Machines that are positioned optimally inside the tank. The machines are programmed based on the cleaning pattern and analysis of tank geometry. The portable AUTOMATIC TANK CLEANING unit is brought onboard when the cleaning job is going to take place. The TCMs are connected to the ATC skid containing pumps, which send a mixture of surfactants and water to the TCMs.
Powerful water jets clean every surface inside the tank following the specially programmed cleaning pattern. A portable slop pump or rig tank pumps transfer the slop back to a wash-water recycling unit inside the ATC unit. There, the liquid phase is separated from the solids. Liquid is directed back to the TCMs to be reused as cleaning fluid until it becomes too contaminated by the fine solids.
At the end of the operation, cleaning fluid and solid waste, predominantly barite, are safely removed from the installation or reused to build new mud volume. In cases where an overboard permit is in place, the process is simplified.
The ATC also comprises customized cleaning chemistry for the specific mud type. The closed-loop system also reuses fluid by separating solids from the liquid. The 44 bbl of water/cleaning liquid prepared at the outset of the cleaning operation is used to clean several tanks. Once fine solids have settled out in the waste container. the liquid can be reused.