Cleaning Agent TC5225M

Problem
An International Oil and Gas Production Company in Europe experienced signs of inefficient separation for its multiphase separator (gas/oil/water/sludge), see Picture 1. After five years of operation the separator showed unusual dirtier water and reduced throughput due to buildup of sludge. The oil company therefore decided to shut down the separator for a visual inspection of separator’s interior. Therefore, the separator must be thoroughly cleaned and decommissioned. It was assumed that the bottom of the separator contained considerable amount of sludge, which is a mixture of sand and other settled hydrocarbons. The oil company decided the separator should be cleaned according to “Non-Man-Entry” practices, which means that during the cleaning job it is forbidden to workers to enter the separator at any time.

Solution
The operator selected a recognized industrial cleaning company, which was specialized in major tank cleaning tasks. The operator requested Rodanco to find a suitable cleaning product with major advantages.

A sample of the sludge and crude oil from an on-shore major oil field in Europe were sent to Rodanco’s state-of-the-art laboratories at Science Park in Amsterdam. Cleaner TC5225M was the most effective product with very interesting advantages. It not only outperformed at room temperatures but also breakdown the sludge quickly into three phases, namely: oil phase at the top; clean water phase at the middle; and clean sand at the bottom (see Picture 2). In the meantime, stakeholders (Rodanco, operator and cleaning company) developed a protocol to safely and effectively carry out the “Non-Man-Entry” cleaning job.

SCANJET* was installed at the top of the separator. Three drains were installed at the bottom of the separator, which were combined together with a manifold and then connected to a vacuum truck with two (~70 m³) settling containers. SCANJET was programmed to spray pressurized liquid inside the separator. The liquid reached almost the entire internal surface of the separator. Part of the free oil was removed by filling the separator completely with water. The cleaning job started after the water was completely drained.

Results
With 3 vacuum trucks (approx. 60 m³) liquid, solids and sludge (Picture 3) were sucked up from the separator. Then, when no sludge came out of separator anymore, the first batch of Cleaner TC5225M in water was prepared (20 m³ of a 10% emulsion). This milky emulsion was then jetted into the separator using the SCANJET in approx. 15 minutes, while continuously draining and removing the loosened sludge. It is essential to keep draining the separator before sand starts to settle again in the separator. Cleaner TC5225M turned the viscous sludge into a slurry under the motion of the SCANJET. Consequently, the slurry drained easily and removed efficiently. Through the side glass of the suction line one could clearly see how well the milky cleaning emulsion turned into a dark grey slurry.

This dark grey slurry was sent to one of the settling containers via the vacuum truck. In stagnant condition Cleaner TC5225M works like a demulsifier and thus the slurry separated quickly in the settling container (Picture 4) into three phases comparable to laboratory tests (Picture 2).

The middle water phase was already clean enough to be jetted again with the SCANJET into the separator (first recycle). This recycle process was repeated three more times.

Now a second batch of Cleaner TC5225M (20 m³ of 5% in water) was prepared for post-cleaning purposes. This second batch was also jetted into the separator, under continuous draining and collecting as previously, but now the slurry was collected in a second settling container. The side glass showed only a light grey colored liquid, which means that most of the crude oil and dirt had been removed from the separator during the first batch. Lastly, the separator was rinsed with 5 m³ of clean water via the SCANJET. The drained water was clear.

For safety reasons VOC’s, O2, CO and LEL values were measured. All volatiles including hydrocarbons were far below the required range and oxygen level was within the normal range.

The plant operators entered the separator without gas-masks and inspected the interior visually. The team was very glad to see the interior of the separator was clean. The heating pipe bundles and the wall were very clean: beyond expectations and far better than previous cleaning jobs. Only at hidden spots (where the SCANJET could not reach) some small deposits were present. Those remaining deposits were removed easily by a water hose. .