Effect of Added Surfactant on Interfacial Tension and Spontaneous Emulsification in Alkali/Acidic Oil Systems

• Published in: Industrial & engineering chemistry research Vol. 33; no. 5; pp. 1150 - 1158
• Main Authors: Rudin, Jeff, Bernard, Camille, Wasan, Darsh T
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.05.1994
• Subjects: 02 PETROLEUM; 020300 - Petroleum- Drilling & Production; ADDITIVES; Applied sciences; CAUSTIC FLOODING; COLLOIDS; Constitution and properties of crude oils, shale oils, natural gas and bitumens. Analysis and characteristics; Crude oil, natural gas and petroleum products; DISPERSIONS; EMULSIONS; Energy; Exact sciences and technology; FLUID INJECTION; Fuels; MICELLAR SYSTEMS; OIL WELLS; PHASE STUDIES; SURFACE PROPERTIES; SURFACE TENSION; WATERFLOODING; WELLS; Alkali; Interface tension; Ionic strength; Crude oil; pH; Extraction; Concentration; Surfactant; Experimental study
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie00029a012

An experimental investigation of the buffered surfactant-enhanced alkaline flooding system chemistry was undertaken to determine the influence of various species present on interfacial tension as a function of pH and ionic strength. Phase behavior tests that monitor the extent of emulsification are sufficient to determine the region of low interfacial tension. Optimization of interfacial tension by adjustment of the ionic strength alone may not necessarily provide the lowest interfacial tension under the best conditions. The pH should be simultaneously optimized along with ionic strength to allow better control over attainment of low interfacial tension. The dominant mechanism by which added surfactant aids in the reduction of interfacial tension is the formation of mixed micelles with the ionized acid. Although added surfactant partitioning from the influence of the un-ionized acid and ionic strength will affect interfacial behavior, the formation of mixed micelles plays a dominant role. Middle-phase formation is possible with a low acid oil using a petroleum sulfonate at a proper pH and ionic strength.