Methods for Identifying Naphthenates-Causing Deposits in Liquid Hydrocarbons during Refining
The present invention describes a method and apparatus to test whole oil to determine if deposits are expected to occur in oil production. The invention specifically address both calcium and sodium naphthenate deposits but may have applications in scale and asphaltene deposition as well. Because hydrocarbon comprising liquids, e.g., crude oil, include a variety of hydrocarbon and heteroatom containing hydrocarbon components, it is often difficult or impossible to identify specific compounds, such as naphthenic acids, present therein. The method includes contacting a hydrocarbon-comprising liquid with gaseous ammonia in order to produce a reaction product, and then isolating the reaction product. The reaction product is then analyzed for the presence of naphthenates by use of an atmospheric pressure ionization mass spectrometry technique, including, but not limited to, electrospray ionization and photoionization techniques, e.g. atmospheric pressure photoionization and laser desorption ionization. The hydrocarbon-comprising liquid can be any liquid including hydrocarbons, such as crude oil, bitumen, a crude oil fraction, a crude oil concentrate, a crude oil extract, a diluted crude oil, or any other product of crude oil or other similar raw materials.
In another embodiment, the invention is drawn to a method for determining whether a crude oil composition will produce commercial naphthenate deposits during crude oil processing. In this case, the analysis step can include comparing mass spectrometry results of the reaction product to standards for naphthenic acids known to form commercial naphthenate deposits. If no reaction product is formed, it can be concluded that the crude oil composition is not likely to form commercial naphthenate deposits. However if the comparing step indicates that the reaction product comprises a naphthenic acid ion present in commercial naphthenate deposits, the composition of the crude oil mixture can be adjusted to reduce the formation of commercial naphthenate deposits.
- Easy to implement
- The deposit produced from the test is easily isolated for mass spectral or other analytical testing