Regresar

Filtration effect on water in oil emulsions stabilization in slop crude treatment

Abstract:

The emulsion (water, crude and solids) remaining in W/O interface after dehydration (water removal) constitutes Slop crude. Its recovery requires more complex processes than conventional treatment of crude because it has a very stable emulsion and vast amounts of fines. In the oil industry filtration is commonly used to treat crudes with such characteristics. Shear effect, resulting from filtration of a Slop crude from west Venezuela, on emulsion stability and thereby on its dehydration was studied. Static stability tests, at laboratory scate, were conducted. They were carried out on diluted Slop crude, unfiltered and filtered with different meshes size, at different temperatures, injection of moisturizing and demulsifying products, and settling time. After treatment, water and sediment content (%W&S) was lower in unfiltered crude than in the filtered one. All unfiltered samples reached commercial specifications (<1 %W&S). The parameter studied to explain how the filtration process affects emulsion stabilization was the determination of droplet size on the Slop crude, before and after filtration. The microphotographs show that filtered samples have smaller droplet size than the unfiltered ones. Thus, evidencing that shear resulting from pressure drops and partial pluggings of meshes lead to decrease in emulsion droplet size and on increase stabilization. This decrease explains why thermochemical dehydration of unfiltered samples is more effective than that of filtered samples. Based on these results, it was concluded that solid separation through filtration, prior to thermochemical treatment, is negative to dehydrate the studied Slop crude because a decrease of droplet size on the dispersed phase is produced, there by stabilizing emulsion even more. Copyright 2007, Society of Petroleum Engineers.