Delineating the pour point and gelation temperature of waxy crude oils

Paraffin deposition in subsea pipelines is a multimillion-dollar problem in the oil industry. The temperature at which a waxy crude oil gels is an important property that determines the initiation of the deposition process. The "pour point," as defined by the standard ASTM test method, is not sufficient to describe the deposition of waxy crudes under flow conditions. The "gelation temperature," explained in this article, is found to be an appropriate measure of the onset of gelation under static as well as flow conditions. Rheological experiments show that the gelation temperature of a wax-oil system is depressed by the shear stress acting on the system during cooling.