Doctoral Dissertations


Vijitha Mohan

Keywords and Phrases

Concentration Dependent Diffusivities; Flory-Huggins Solution Theory; Heavy Oil Recovery; Mass Transfer; Swelling Factor; VAPEX Process


"Heavy oil, sometimes called bitumen, is known for its high viscosity (above 100 cp) and low API gravity (below 22⁰). In most cases, viscosity reduction is needed for the final product. There is a considerable amount of heavy oil in Alberta, Canada and the world's largest heavy oil deposit is in Venezuela. Yet less than 1% of it can be recovered because of its high viscosity. For shallow reservoirs, it is possible to resort to open cast mining. For deeper reservoirs, steam is used at ~ 350 ⁰C which gets the oil viscosity reduced to 1cp, which can now be drained out. This process requires large amount of water to make steam, the used water cannot be reused due to presence of high levels of bitumen in it and is currently leading to pollution. The recovered bitumen being highly viscous needs a diluent like naphtha for transportation. Therefore another method is devised which involves using gaseous or liquid solvents directly to bring down the viscosity of bitumen. One such method, vapor extraction (VAPEX) process uses gaseous solvents like hydrocarbon solvents and CO2 to reduce bitumen viscosity. Vaporized solvents is introduced laterally to bitumen to reduce its viscosity and the less viscous bitumen drains under gravity. Solubility of solvents in bitumen is analyzed first. As solvents solubilize, it diffuses into bitumen and the diffusivity is strongly concentration dependent. The concentration dependence of solvent diffusivity in bitumen is measured next. Knowing the solubility and diffusivity of solvents, a model is used next to simulate oil recovery. It predicts an optimum solvent for this oil recovery process"--Abstract, page iv.


Neogi, P. (Partho), 1951-

Committee Member(s)

Smith, Joseph D.
Park, Joontaek
Rezaei, Fateme
Bai, Baojun


Chemical and Biochemical Engineering

Degree Name

Ph. D. in Chemical Engineering


Missouri University of Science and Technology

Publication Date

Spring 2017

Journal article titles appearing in thesis/dissertation

  • Flory-Huggins solution theory for heavy oils
  • Concentration dependent diffusivities of model solvents in heavy oil
  • Revisiting Butler-Mokrys model for VAPEX process


xii, 98 pages

Note about bibliography

Includes bibliographic references.


© 2017 Vijitha Mohan, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Thesis Number

T 11105

Electronic OCLC #