Characterization of asphaltenes and resins
- Rice Univ., Houston, TX (United States)
The colloidal nature of asphaltenes in naturally occurring petroleum reservoir fluids is well-recognized. Problems involving liquid-liquid and fluid-solid phase separation in petroleum systems have typically been addressed using models based on classical solution theory, e.g., as modified for use in macromolecular solutions. Phase behavior of asphaltenes in petroleum fluids is notably different from phase behavior of most macromolecular solutions, in that phenomena associated with amphiphilic materials and colloidal phenomena are also involved. In order to better understand such phenomena, it is important to determine the physicochemical and interfacial characteristics of the amphiphilic substances and of the related materials. Such characteristics include the critical micelle concentration and the hydrophilic-lipophilic balance indices (or equivalent) for the amphiphilic substances, and for their subtractions, in cases where the amphiphilic substance is polydisperse. For a variety of well-defined systems, experimental phase behavior data and their theoretical interpretation enhance our understanding of complex phase behavior of asphaltenes in natural fluid systems. Effectiveness of surface-active molecules in water-and-oil systems is related to the relative contributions of their polar hydrophilic {open_quotes}head{close_quotes} and nonpolar lipophilic {open_quotes}tails.{close_quotes} The balance between hydrophilic and lipophilic interactions of a surface active agent is one indicator of its relative effectiveness as an emulsifier in oil-water systems. The empirical concept of hydrophilic-lipophilic balance (HLB) as a characterizing parameter for surfactants was introduced by Griffin. Characterization of surfactant substances, in terms of their HLB index, is an established method used in the cosmetic, pharmaceutical. detergent, and petroleum industries.
- OSTI ID:
- 269536
- Report Number(s):
- CONF-9502114--Vol.1
- Country of Publication:
- United States
- Language:
- English
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