Two methods used to study and compare the reactivity of different oils to oxidation are Accelerating Rate Calorimetry (ARC) and Differential Scanning Calorimetry (DSC). This information is useful for screening reservoir for air injection EOR.
One of the most important pieces of information from these thermal scanning devices is the onset temperature for exothermic activity. It is important to realize that the measured "onset" threshold value very much depends on the instrument sensitivity and the procedure by which the test is performed.
The ARC technique minimizes heat losses from the sample to its environment by matching the temperature of the apparatus to that of the sample. DSC techniques, on the other hand, measure the difference in the amount of heat required to increase the temperature of a sample and reference as a function of temperature.
Onset temperatures determined by DSC can be as much as 50 degrees Celsius higher than that reported from adiabatic (ARC-type) instruments. ARC measurements should therefore provide more realistic estimates of ignition (onset) temperature.