Circulating Tank Bottoms in the Oil and Gas Industry: Techniques and Best Practices

Introduction to Circulating Tank Bottoms in Oil and Gas

The process of circulating tank bottoms is crucial in the oil and gas industry, especially for ensuring the efficient operation and maintenance of storage facilities. This practice involves the removal of residues and sludge from the bottom of storage tanks, which can otherwise impede the smooth operation and maintenance of the facility. Understanding the methods and techniques used in this process is essential for optimizing performance and safety in oil and gas operations.

Industry Practices for Tank Bottom Circulation

In the oil and gas industry, the circulation of tank bottoms is a common practice, particularly in large-scale storage facilities such as Floating Production Storage and Offloading (FPSO) vessels. These vessels, like the FPSO Egina and the converted FPSO Aseng SBM, play a vital role in extracting, processing, and storing petroleum products.

Use of Diesel Fuel Oil and Other Liquids

One common method of circulating tank bottoms involves diluting heavier petroleum residues with diesel fuel oil or other lighter liquids. This dilution helps to dissolve the residual materials and create a more uniform mixture that can be easily pumped. The process often involves the addition of air or agitation to further break down the mixture, lowering its viscosity and making it pumpable.

ASTM Testing and Results

ASTM testing of tank bottoms typically reveals higher Bottom Sediment and Water (BSW) and higher ash and sulfur contents. These tests provide important information about the condition of the petroleum liquid and help in determining the optimal method for circulating the tank bottoms.

Floating Production Storage and Offloading (FPSO) Vessels

FPSOs, such as the new-built FPSO Egina and the converted FPSO Aseng SBM, are designed to perform multiple functions including the extraction, processing, and storage of oil, gas, and water. These vessels are equipped with fixed tank-cleaning guns, known as COW (Crude Oil Washing) guns, which are used to clean the cargo tanks during the offloading process. The COW guns use the hero turbine principle to rotate and deliver a jet of crude oil onto the tank sides, corners, and bottoms, effectively rinsing away residues.

Crude Oil Washing (COW) Process

The COW process is not only used for cleaning but also in a method called Crude Oil Washing, where hot sea water is used to wash the tanks after the COW operation and before maintenance. This method ensures that the tanks are completely free of oil deposits, thus reducing the risk of explosions and other safety hazards.

Fixed Tank-Cleaning Guns and Safety Considerations

These fixed tank-cleaning guns, or COW guns, operate under inert conditions to avoid the risk of explosions. They are activated during the offloading process, when crude oil is drawn off and the tank cleaning guns are used to clean the remaining residues. The guns are driven by the crude oil itself, eliminating the need for additional energy sources, which is a practical and safe approach.

Summary of Techniques and Best Practices

The circulation of tank bottoms in the oil and gas industry involves various techniques, primarily centered around the use of diesel oil and COW guns for cleaning. These methods ensure that the tanks remain clean and operational, reducing the risk of sediment accumulation and enhancing the safety and efficiency of oil and gas operations.

Keywords

.slot1: FPSO slot2: Tank Cleaning slot3: Crude Oil Washing (COW)

Conclusion

Maintaining the cleanliness of tank bottoms is essential in the oil and gas industry. The use of diesel oil and specialized COW guns, along with rigorous testing procedures, helps in ensuring the efficient and safe operation of storage facilities. By adhering to these best practices, oil and gas operations can enhance their overall performance and safety.