Structure of waxy crude oil emulsion gels

The phase separation of paraffinic solids from crude oil constitutes a major operating issue for the petroleum industry, in view of the fact that the association of wax crystals into a disordered spanning network can lead to severe flow assurance problems. Although the presence of water in crude oil is quite common, its impact on waxy crude oil gelation and rheology has not received much more attention in the literature. In this study, we show that the presence of water above a threshold value can greatly enhance gel formation, changing both the pour point temperature and the yield strength. The rheological characteristics of crude oils are examined both above and below the gel point and a qualitative interpretation of the structure of waxy crude oil gels in the presence of water is proposed. The results suggest that the impact of emulsified water on pour point and gel rheology needs to be added to the standard tests conducted on crude oils during field development studies, particularly for those offshore developments with multiphase production. (c) 2007 Elsevier B.V. All rights reserved.