Total Chloride Analysis in Petroleum Crude Samples: Challenges and Opportunities

Abstract

The presence of chlorides in crude oil needs to be continuously monitored because it is necessary to control the presence of these salts before introducing crude oil to the refining units. These chlorides, if not removed, can react to form a highly corrosive hydrochloric acid in areas such as crude tower overheads, leading to severe operational issues. Additionally, the presence of high-boiling-point salts is very detrimental; small quantities could provoke severe damage in different units such as heaters and exchangers. Therefore, a portfolio of analytical techniques or industry standard methods is routinely used to quantify chloride in crude. Regardless of the analytical method selected, essential aspects, such as potential bias among technologies, compatibility of sample type with the detection technique, as well the potential impact on the detection technique of having variable heteroatom content, such as sulfur and nitrogen present in the feed, could compromise data reliability. In this chapter, our goal is to address these aspects by evaluating different detection techniques such as combustion ion chromatography, monochromatic wavelength dispersive X-ray fluorescence spectrometry, and inductively coupled plasma mass spectrometry (single quadrupole) on a standard reference material such as National Institute for Standards and Technology 1634c (Trace Elements in Fuel Oil) and on a suite of selected crude oil samples having different characteristics. Additionally, we will discuss how the nature of the sample is the key to obtaining the most accurate and reliable data. Finally, understanding the challenges associated with the homogeneity of the sample on the total chloride quantitation in petroleum crudes using monochromatic wavelength dispersive X-ray fluorescence spectrometry, a technique that is widely used in the oil and gas industry, will be addressed.