Emulsion Formations

Water production is a major area of concern for crude oil production; this is especially true in steam assisted gravity drainage production. Produced water from the reservoir as well as condensed water from the steam causes the oil to be produced in the form of emulsions.
Emulsions are colloidal dispersions of liquid in another liquid (oil in water), that is, one liquid is microscopically dispersed in the other liquid. Despite the thermodynamic tendency for these liquid in liquid emulsions to separate naturally in order to reduce the interfacial tension between the two liquid phases, the emulsions are formed by kinetic stabilization. Three conditions must exist for kinetic stabilization and therefore, the formation of emulsions
  1. An existence of two liquid phases, from a SAGD point of view, this is primarily caused by condensed water from the steam injection
  2. Surfactants, either naturally or from chemically injected sources. Surfactants are substances which decrease the surface tension of a liquid.
  3. Shearing or mixing, in oil and gas productions, this may be the result of flow through tubes, release of solution gas causing agitation of the fluid, and for SAGD specifically, the result of injected steam agitation of the bitumen.

The most common type of oil emulsions encountered under normal oilfield production conditions is the emulsion in which water droplets is dispersed in oil. During SAGD operations, however, the extracted fluid contains oil dispersed in water; this is generally referred to as a reverse emulsion. Reverse emulsions are generally difficult to break; however, the necessity of breaking these reverse emulsions is crucial due to the limited number of disposal wells available as well as the high steam demand of SAGD operations requiring reuse of the produced water. More importantly, from the perspective of fouling, high efficiency in reverse emulsion breaking will lead to a fewer number of available fouling agents to cause unwanted depositions on the heat exchangers downstream.