Paper Number
EF6 

Session
Emulsions, Foams, and Interfacial Rheology

Title
Does interfacial asphaltene aggregation actually stabilize crude oil/water emulsions through enhanced interfacial rheology?

Presentation Date and Time
October 9, 2017 (Monday) 1:30

Track / Room
Track 1 / Crystal A

Authors (Click on name to view author profile)

1. Rahman, Minhazur (Texas Tech, Mechanical Engineering)
2. Lin, Yu-Jiun (Rice University, Chemical Engineering)
3. Biswal, Sibani Lisa (Rice University, Chemical Engineering)
4. Christopher, Gordon F. (Texas Tech, Mechanical Engineering)

Author and Affiliation Lines (in printed abstract book)
Minhazur Rahman¹, Yu-Jiun Lin², Sibani Lisa Biswal², and Gordon F. Christopher^1
1Mechanical Engineering, Texas Tech, Lubbock, TX 79409; ²Chemical Engineering, Rice University, Houston, TX 77005

Speaker / Presenter 
Rahman, Minhazur

Text of Abstract
Surface active molecules play a key role for stabilizing water/crude oil emulsions. The stabilized emulsions create a range of flow assurance problems primarily in the transport and separation. The leading theory reinforced by numerous studies in the literature is that interfacial aggregation of Asphaltenes play a key role. Thus, it is important to understand how the interfacial rheological behavior of Asphaltenes at an oil/water interfaces is affected by relevant physical parameters.

In this work, we study 2 specific questions. First, what is the role of asphaltene surface concentration on interfacial rheology, and secondly how representative are model oils of in comparison to real crude systems. To study these questions, a Double Wall Ring (DWR) geometry with a modified base to allow visualization was used to characterize the interfacial viscosity, moduli and yield stress along with associated microstructure of the interface on a model oil (composed of toluene and dissolved asphaltenes at a range of weight concentrations) and crude oil at a water/hexane interface. As asphaltene concentration on the interface increases, the resulting interfacial film becomes more elastic with pronounced yield stresses, and denser larger structures are seen as well as visible fractures at high stresses. In comparison, lower concentration films are more viscous with pronounced shear thinning. Interestingly, when comparing crude oil to model oils with the same asphaltene content, crude oils behave very differently. Asphaltene concentrations in crude based on model oil results should create elastic, yielding films. However, crude films are viscous without any pronounced elasticity or yield. This indicates that other interfacial components in the crude are impacting film formation, and the multitude of work on model oils may less applicable to actual crude emulsions.