An Investigative Study of Potential Emulsion Problems Before Field Development

Abstract

Before the development of a field, it is worthwhile to determine the characteristics of crude-oil emulsions. This may be even more important if the wells are to be equipped with electricalsubmersible pumps (ESPs) which can create a shearing environment resulting in tight emulsions. One such study was conducted to determine the characteristics of emulsions from a cluster of oil fields planned for development. The proposed development is to produce from three fields and several different reservoirs. The central processing facility (CPF) will process ≈500,000 B/D oil and 50,000 B/D of water. Previous studies determine the impact of ESP on emulsions and on the ESP design (horsepower) and the possibility of demulsifier injection downhole. The emulsion properties are also necessary for the design of central wet crude handling facilities. A series of emulsion tests was conducted with crudes from different reservoirs at bottomhole and surface temperatures, range of water cuts, and shearing conditions. The results are provided in terms of "relative" tightness of emulsions from different reservoirs. The viscosities of various emulsions were also determined. The results indicate that demulsifier injection facilities will be needed at the wet crude handling facilities and possibly in wells from one reservoir that has a high asphaltenic and viscous crude. This paper provides a framework of laboratory emulsions studies that can provide valuable information for the design of CPFs before they are built. This paper also discusses some practical aspects of demulsifier treatment programs, including demulsifier selection and optimization and methods to prevent emulsion problems.

The influence of asphaltenes subfractions on the stability of crude oil model emulsions

“…W/O emulsions must be treated to remove the associated water and inorganic salts, to obtain oil with proper specifications for transport, storage and exportation and to reduce the corrosion and contamination of catalyzers at processing plants. 1,2 W/O emulsions are stabilized by emulsifiers (surfactants), which tend to migrate and concentrate at the W/O interface, forming a film that reduces the interfacial tension between the phases, promoting the dispersion of water droplets in the continuous phase and inhibiting their coalescence. Some natural emulsifiers are present in crude oil, such as asphaltenes, resins and organic acids and bases.…”

Emulsion Inhibiting Components in Crude Oils

“…To overcome the problems associated with emulsions, various techniques have been developed such as the application of heat and the injection of demulsification chemicals, for example, at the well head or the processing facility. 5 Invariably these remedies are costly; however, given the consequences of emulsion formation, they are often employed as a pre-emptive measure. This is despite the fact that it is extremely difficult to predict reliably whether an emulsion will actually form in a given production system.…”

“…Once at the processing site the emulsion must be broken to recover the oil for further processing. To overcome the problems associated with emulsions, various techniques have been developed such as the application of heat and the injection of demulsification chemicals, for example, at the well head or the processing facility . Invariably these remedies are costly; however, given the consequences of emulsion formation, they are often employed as a pre-emptive measure.…”