Effect of Emulsion Breakers on Interfacial Tension Behavior of Heavy Oil–Water Systems

Abstract

Bottle testing for emulsion breakers (EBs) in steam-assisted gravity drainage (SAGD) operations is a standard practice; however, it has been observed that, in some cases, EBs recommended via bottle tests can fail during field trials as a result of conditions being disparate, such as higher temperatures and pressures in the field that cannot be safely or easily replicated in the lab. To make better EB recommendations, an optimized methodology based on interfacial rheology measurements was developed. Compressibility tests performed at different temperatures (80–120 °C) were used to compare effect of EBs on parameters such as initial compressibility, initial interfacial tension, phase transition ratio, and drop crumpling or detachment ratio (ratio of the compressed surface area to the original surface area at which the interface starts to collapse or at which the drop detaches). Furthermore, the addition of the EB to the oil phase versus aqueous phase was investigated. The effects of EBs at the oil/brine interface can be quantified using compressibility tests at temperatures and pressures similar to those encountered in the field. This approach shows a good correlation with field results and demonstrates that these techniques can be used to supplement the standard bottle test for more effective screening of EBs.

Experimental Evaluation of a Surfactant/Compound Organic Alkalis Flooding System for Enhanced Oil Recovery

“…It is acknowledged that the ultralow IFT and favorable emulsification are essential to a chemical flooding system for enhanced oil recovery, and a period of contact time between flooding solution and crude oil is necessary for chemicals to reduce the IFT and emulsify the oil in the process of chemical flooding . Data in Figure b also verify that about 5 min is spent for the selected SMM system in reducing the water/oil IFT to an ultralow value under laboratory experimental conditions.…”

Experimental Study of Produced Fluid Emulsification during Water/Steam Flooding for Heavy Oil Recovery

“…If the active substances of heavy oil are adsorbed on the interface, a W/O emulsion would form. Oil-in-water (O/W) emulsion would form if the active substance of water solution (such as chemical flooding would add some active substances into the water phase) is adsorbed on the interfacial film. − Active substances in heavy oil gradually adsorb on the oil–water interface under the shear action of porous media, forming a stable interface film with certain strength because there are no active substances adding into the water phase during water/steam flooding. − Most of the natural emulsifiers (active substances) in heavy oil have lipophilic and hydrophobic properties, so they generally form a stable W/O emulsion. , Natural emulsifiers in heavy oil are adsorbed on the oil–water interface to form a viscoelastic film with a certain strength, which creates kinetic obstacles to the coalescence of water droplets and stabilizes the W/O emulsion. − …”