Crude Oil

Crude Oil
Crude oil is the primary input to the refinery. Depending on its quality, it is commonly classified as sour or sweet crude oil. The crude oil type is a decisive factor in the refinery design & operating conditions as well as the product yields. Crude oil characterization is therefore critical in the refinery industry.

Refineries are obligated to monitor several different parameters in crude oil production: TAN value, water content, salt content, and organically bound chlorine. On this page, you will find more information on all of these parameters and have the option to download relevant application notes. 

Total Acid Number in Crude Oil by Thermometric Titration

Sulfur species and naphthenic acids are the main contributors to efficiency-decreasing corrosion in the refining process. By monitoring the acidity of crude oil and the associated process oils, billions of dollars are saved annually by avoiding unexpected shutdowns and preserving expensive treatment chemicals. Thermometric titration improves upon the traditional D664 analysis technique by using a sensor that is insensitive to difficult matrices, requires lower solvent volumes, and completes sample analysis in often less than two minutes. In addition to electrode fouling, traditional potentiometric TAN titrations can require up to 120 mL of solvent and may create a need for the analyst to titrate to an alternate buffer endpoint when a true inflection is not apparent.


Total Acid Number in Crude Oil as per ASTM D664

Titration has long been the preferred method for analysis for total acid number (TAN) in petroleum products as per ASTM D664. Even though a new analysis method involving thermometric titration seems to improve greatly upon TAN determination by potentiometric titration, the traditional method is still widely used today. 

Water Content in Crude Oil According to ASTM D4347 and ASTM D4928

Water occurs as a contaminant in virtually all petroleum products. It reduces lubricant properties, promotes microbial oil degradation, leads to sludge formation in the tank and promotes corrosion. While water boils and contributes to a partial degreasing at higher temperatures, temperatures below the freezing point cause formation of ice crystals and a rapid decrease in lubricity. Therefore, it is critical to know the water content of petroleum products.

Karl Fischer titration is one of the best methods for determining water content in petroleum products due to its excellent reproducibility and accuracy as well as its ease of use. Measurements can be performed using volumetric or coulometric Karl Fischer titration. Because of the low water content in petroleum products, KF coulometry is usually applied.


Link to AW: Water Content in Crude Oil as per ASTM D4928

The Metrohm 874 Oven Sample Processor helps simplify water content determination in crude oil. 

> See how


Determination of Salt in Crude Oil as per ASTM D6470 & ASTM 3230

Crude oil contains salt, dissolved or suspended. The salt can lead to fouling and corrosion of heat exchangers and distillation overhead systems. Further salts are detrimental for catalysts in the downstream conversion processes.


> Application Note: Determination of Salt in Crude Oil

Our mobile pH meters are the perfect choice for salt determination in the lab or on the go. > Check them out!


Organically Bound Chlorine as per ASTM D4929

Organically bound chlorine present in petroleum products decomposes at high temperatures and forms hydrochloric acid which is highly corrosive and can cause damage to the distillation columns. Before measurement, sulfur compounds and inorganic chlorides can be removed by distillation and subsequent washing as described in ASTM D4929.


Our Titrando Titrator allows fast and accurate determination of organically bound halides accodring to ASTM D4929

> Go to Titrando Page


Organically Bound Chlorine in Crude Oil by Combustion IC

The burning of sulfur-containing fuels leads to the emission of air-polluting sulfur oxides into the atmosphere. Furthermore, high sulfur concentrations have an adverse effect on the ease of ignition of fuels and their stability during storage. Halogen concentrations in the refinery process must also be analyzed due to the corrosion risk. As a result, a fast and reliable method for determining the halogen and sulfur contents is required.

Combustion IC enables the sulfur and halogen content in combustible solids, liquids, and gases to be determined by combining combustion digestion (pyrolysis) with subsequent ion chromatography. 


> Download 2 Application Notes for Chlorine Determination in the Refining Industry

Combustion IC can be fully automated and excels in its high sample throughput, large measuring range, and excellent precision and accuracy. > See how it works