Paper Number
GG21 

Session
Arrested Systems: Gels and Glasses

Title
Modeling temperature-dependent rheological aging in bentonite suspensions

Presentation Date and Time
October 13, 2021 (Wednesday) 10:40

Track / Room
Track 6 / Ballroom 1

Authors (Click on name to view author profile)

  1. Rathinaraj, Joshua David John (Massachusetts Institute of Technology, Mechanical Engineering)
  2. Lennon, Kyle R. (Massachusetts Institute of Technology, Department of Chemical Engineering)
  3. Gonzalez, Miguel (Aramco Americas)
  4. Santra, Ashok (Aramco Americas)
  5. Swan, James W. (Massachusetts Institute of Technology, Department of Chemical Engineering)
  6. McKinley, Gareth H. (Massachusetts Institute of Technology, Mechanical Engineering)

Author and Affiliation Lines (in printed abstract book)
Joshua David John Rathinaraj1, Kyle R. Lennon2, Miguel Gonzalez3, Ashok Santra3, James W. Swan2 and Gareth H. McKinley1
1Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; 2Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142; 3Aramco Americas, Houston, TX 77084

Speaker / Presenter 
Rathinaraj, Joshua David John

Keywords
colloids; gels; glasses; rheology methods; suspensions

Text of Abstract
Clay slurries are both ubiquitous and essential in the drilling industry, most commonly as drilling fluids. Due to its natural abundance, bentonite clay is often the de facto choice for these materials. Understanding and predicting the mechanical response of these fluids is critical for safe and efficient drilling operations, to avoid undesired effects such as back-flow which may cause significant economic and environmental harm. However, the rheological modeling of bentonite clay suspensions is complicated by the fact that microscopic arrangements of particle aggregates lead to a continual evolution of the viscoelastic properties with time. Ergodic relations fundamental to linear viscoelastic theory, such as the Boltzmann superposition principle, do not hold in this scenario of ‘rheological aging’. In this work, we present an approach for modeling the linear viscoelastic response of aging bentonite suspensions across a range of temperatures, which is based on a transformation from laboratory time to an effective ‘material time’ in which the typical relations of non-aging linear viscoelastic theory hold. In particular, we model bentonite suspensions as fractional Maxwell gels which respond in material time, in parallel with a Newtonian viscous mode which responds in laboratory time. This approach is supported by experimental stress relaxation and exponential chirp data, which are used to develop fits of the model parameters.