Method of Assessing the Level and Quantity of Sludge in Crude Oil Storage Tanks

When crude oil is stored in large tanks, invariably high-molecular-weight organic sediments (paraffin) are deposited but the resulting sediments contains also solid particles (sand, silt, corrosion products, etc.) and also water. After some period of in-service of tank, these deposits build up to form a sludge, which causes a reduction in the storage capacity. These high in hydrocarbons a valuable raw material could be proper recovered and recycled back to the refining process. Therefore, it is significant to know the sludge characteristics shape and volume to define the best form of treatment (maintenance of tank for control of level of sludge) and removal method (in case of out of service and opening of tank). The knowledge about volume and shape of such sludge inside tanks is important for user of tank farm due to a reasons such as e.g. maintenance of storage tanks and control of level of sludge inside them, when conventional treatments are used to remove crude oil sludge, there is a potential for high environmental impact, the choose of the method of cleaning is very essential. In this paper will be presented AE technique and thermography for assess of level, volume and shape of sludge inside storage tank. In 2017, the Office of Technical Inspection launched a project to develop a system for assessing the level and quantity of sludge in crude oil storage tanks, using the AE technique and thermography. As part of the project implementation, UDT started cooperation with companies, that are the leader in oil and fuel logistics in Poland. In the following years, a complete methodology and procedure for assessing the level, volume and shape of sediments was developed, as well as a process of verifying the results. A description of the invention was prepared and submitted to the Patent Office.