USE OF PULSED NMR-SPECTROSCOPY TO MEASURE THE AMOUNT OF SOLID IN WAXYCRUDES

Paraffin crystallization in crude oils and in gas condensates is a maj or problem for petroleum exploitation. Thermodynamic models are used t o evaluate the risk. With them, one calculates the Wax Appearance Temp erature (WAT) as well as the crystallized fraction as a function of te mperature, for temperatures below the WAT. During development, these m odels are tested against experimental data. Although different methods for measuring the WAT are available in the literature and at petroleu m companies, such methods unfortunately do not exist for measuring the crystallized fraction as a function of temperature. In this work, we have developed a low resolution NMR method for measuring the crystalli zed fraction as a function of temperature. The method was first evalua ted using pure samples and was then applied to crude oils. The results were compared to those obtained both from differential calorimetry an d from the model.