A Review of the Seepage Mechanisms of Heavy Oil Emulsions during Chemical Flooding

Abstract

Chemical flooding plays an important role in enhancing oil recovery due to many reasons, including the viscosity-increment effect of polymer, wettability alteration effect of surfactant, and the formation of emulsions, which have been known to effectively increase the swept area and oil displacement efficiency, hence increasing heavy oil recovery. Laboratory tests and pilot trials of alkali–surfactant–polymer (ASP) injection show that the oil recovery of the emulsified system is 5% more than the cases where no emulsions existed. Therefore, it is of great significance to study heavy oil emulsions and its field application for enhanced heavy oil recovery. This paper discusses a thorough overview of the most fundamental ASP flooding mechanisms, along with some examples of laboratory experiments and field trials. In addition, the formation conditions and the interfacial characteristics of heavy oil emulsions are also discussed, mainly ASP flooding, and then the seepage mechanisms of these emulsions are investigated. The relationship between the formation of heavy oil emulsions and the enhanced heavy oil recovery effect by chemical flooding is discussed through core flooding experiments at the reservoir temperature and some field pilots to reach the optimum heavy oil recovery.

Emulsification and stabilisation technologies used for the inclusion of lipophilic functional ingredients in food systems

“…There are typically three mechanisms associated with creaming, but the process is usually governed by one. These mechanisms are gravitational drainage, packing and shrinkage of the droplet layer, and flocculation during the creaming process [ [158] , [159] , [160] ]. Flocculation is a process whereby droplets come together to form loose clumps or aggregates.…”

“…These aggregates will then interact to form a more rigid, compact structure with a higher packing density than the primary droplet structure. The interaction between droplets is due to an attractive interaction potential, which is always a result of a free energy increase in the system [ [158] , [159] , [160] ]. Flocculation is driven by many mechanisms, including van der Waals forces, coalescence, bridging flocculation, and hydrophobic interaction.…”

“…This results in larger droplets growing and smaller droplets shrinking. The difference in the rate of material movement in and out of droplets is what separates this process from coalescence [ [158] , [159] , [160] ]. Coalescence is a dynamic process influenced by many factors.…”

“…It is generally agreed that, before two droplets can coalesce, they must come into close contact with one another. The force that brings droplets together is the disjoining pressure [ [158] , [159] , [160] ].…”

Relation between Conventional and Starch-Assisted ASP Injection and Impact of Crystallinity on Flood Formation

“…Chemical flooding, especially alkaline–surfactant–polymer (ASP), plays an important role in enhancing oil recovery because of the synergy of its three components: alkaline; surfactant; and polymer. It is a very promising technology that can make incremental oil recovery of up to 30% from the original oil in place (OOIP) [ 1 ]. Lowering the interfacial tension (IFT) between oil and water phases, changing the rock wettability from oil-wet to water-wet, emulsifying the oil and water, and improving the mobility ratio between the displaced solution and the displacing one are the four basic mechanisms that interpret the role of ASP flooding in improving oil recovery [ 2 , 3 , 4 , 5 ].…”