Effect of baseline selection on wax content of crude oil tested by DSC method

When the Differential Scanning Calorimetry (DSC) is used for testing wax content and latent heat of wax precipitation in crude oil, the calculation results are more affected by the selection of baseline. To deal with the inconsistency of baseline selection, the crude oil of two oil production blocks in Daqing Oilfield was measured by the DSC method, and the DSC curves of crude oil cooling were plotted. Then, the DSC curves of two oil samples were analyzed by two commonly used baseline selection methods to calculate the wax contents. The calculated wax contents were compared with the values measured by alumina adsorption method. It is shown that the relative errors of two oil samples are 4.7% and－3.1% respectively when the testing results are processed by means of interpolation baseline method. And the relative errors are 52.6% and 34.7% respectively when the reverse extension line method is adopted. To sum up, the interpolation baseline method is more suitable for baseline determination when DSC is used to measure wax content and latent heat of wax precipitation in crude oils, while the calculation results with the reverse extension line as the baseline are of great errors.