Rare earth elements (REE) refer to the lanthanide elements, from La to Lu, which generally exhibit similar chemical properties (Henderson, 1984 and Rollison, 1993). Their chemical similarities induce systematic partitioning in a variety of systems. Therefore, REE and their concentration patterns have been widely used in studies of the origin of materials, and the physical and chemical environmental variables of various geological processes (Henderson, 1984, Murray et al., 1990 and Jiang et al., 2007). Less attention has been paid to the application of REE to petroleum systems.