Case Study 2 — Desludging Tank No. 4

The Challenge

Tank No. 4 located in the Ras Lanuf Tank Farm — a 500,000-barrel heavy crude oil storage tank — had accumulated significant sludge deposits on the tank floor over years of continuous service. The build-up was reducing the tank's effective storage capacity, increasing the risk of accelerated floor corrosion, and preventing the internal inspection needed to assess the structural condition of the asset.
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The client required a cleaning solution that could safely remove the sludge from a large, complex tank environment while maximising the recovery of valuable hydrocarbons from the sludge layer — rather than disposing of them as waste. The operation needed to be executed with minimal disruption to terminal operations and to the highest safety and environmental standards.

The VAOS Approach

VAOS deployed its automated tank cleaning and hydrocarbon recovery system — a fully enclosed, remotely operated process that eliminates the need for personnel to enter the tank during cleaning operations, removing the confined space entry risks associated with conventional manual cleaning methods.
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The system used a combination of heated diluent injection, high-pressure jet cleaning heads and continuous mechanical circulation to break down and homogenise the heavy crude sludge layer. As the sludge was progressively mobilised, the hydrocarbon-rich liquid fraction was continuously pumped out of the tank and passed through onsite separation equipment to recover usable crude oil for reintroduction into the production stream.
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Throughout the operation, VAOS maintained continuous monitoring of the cleaning process from an external control station, allowing real-time adjustment of pressures, temperatures and flow rates to optimise both cleaning effectiveness and hydrocarbon recovery.
 
Full waste management and environmental controls were in place throughout, ensuring that all non-recoverable material was handled in compliance with applicable environmental regulations.

Result

The project achieved exceptional results, recovering 120,896 barrels of crude oil from the tank sludge — a recovery efficiency of 99.50%. The tank was returned to full operational capacity following the cleaning operation, with the internal condition confirmed by post-cleaning inspection. The recovered hydrocarbon volume represented significant commercial value for the client, substantially offsetting the cost of the cleaning operation.

Impressions