Abstract: Depositions in pipes are encountered in many industrial applications. These include, but are not limited to, fouling in pipelines and heat exchangers, deposits in the form of hydrate, asphaltene or wax in oil and gas pipelines, wellbores and processing facilities. These processes usually take place in the presence of multiphase flow environment. For example, asphaltene deposition in multiphase (oil-water-gas-sand), hydrate deposition in (gas-water-sand) flows and foulings in heat exchangers. 

Comprehensive understanding of the deposition processes is important to control or prevent such processes. Numerical models capable of incorporating physics important to these processes are crucial to understanding and with time possibly accurately predict some of these processes. The complications in the modeling of these processes include, but are not limited to, large length-to-diameter ratio of the flow passages, the presences of moving (fluid-fluid, fluid-gas, fluid-solid and gas-solid) interfaces and the associated equations of state. 

In this talk, we present our work on the modeling of asphaltene deposition in very long wellbores. Due to the large length-to-diameter ratio full computational fluid dynamics (CFD) simulations are impractical and most of the time impossible. We present our simplified approach to model this very challenging multiscale problem. Multiscale spanning asphaltene precipitation of nanometers, asphaltene aggregation to micrometers, deposition thickness of millimeters, pipe diameter of centimeters and the pipe length of kilometers. Though the span of the physical dimension is large, the physical processes still occurs in the continuum regime. Over the course of the presentation, we shall bring the audience from ground zero to the current state of the art.

We will present validation of our approach using simple test cases with known analytical solutions, with available experimental data and also with available field data showing the upscaling of our approach to pipe length of 15,000 ft with a pipe diameter of 2.75 in.

Bio: John Chai is currently a Professor at the University of Huddersfield, UK. He is an Editorial Board member of Computational Thermal Sciences, Associate Editor of the ASME Journal of Thermal Science and Engineering and Heat Transfer Engineering. He is an elected Fellow of ASME (American Society of Mechanical Engineers). Prior to UK, he held faculty positions in United Arab Emirates (UAE), Singapore and Tennessee, USA. 

He received his B.S. (with First-Class Honors) in Mechanical Engineering from the University of Windsor, Canada and his M.S. in Mechanical Engineering from the University of Wisconsin-Milwaukee. In 1994 he graduated from the University of Minnesota with a Ph.D. in Mechanical Engineering where he worked under the supervision of Prof. Suhas V. Patankar.

He has published over 90 journal articles, over 100 conference articles and contributed a chapter to the second edition of the Handbook of Numerical Heat Transfer. According to Google Scholar, his works have been cited almost 4000 times and his H-index is 27. He has worked on over US$5M in funded research projects in USA, Singapore and UAE.

His research interests are in the development of numerical techniques for complex multiphysics transport phenomena encountered in multi-phase flows and fluid-structure interactions. Applications include, but are not limited to, digital (droplet-based) microfluidics, wet chemical etching, renewable energy, asphaltene (cholesterol) depositions and numerical methods for oil and gas industry.​