• The candidate must have a PhD in fluid mechanics and have experience in the numerical simulation of multiphase flows with interface tracking.  

• Knowledge of oil-water flows is appreciated.  

• The candidate must be skilled in programming.  

• The candidate must be a team-worker and be proficient in English.  

We offer a post-doc position on the topic of “core-annular flows” which is a flow regime that can occur in pipes transporting a viscous oil and water. The postdoctoral work will take place at the Institute of Fluid Mechanics in Toulouse (IMFT) under the supervision of Dominique Legendre (IMFT) and Roel Belt (TotalEnergies). The post-doc will be employed by TotalEnergies with a work contract of 18 months, which can be extended up to 24 months.  

For oil fields producing a viscous crude oil, like the Tilenga field that we are currently developing, we need to transport the viscous oil in a pipe over a long distance. If the viscous crude oil is transported alone, the pressure drop would be so large that the capital expenses and the energy consumption would be prohibitive for the development of the field. In the case of Tilenga, this issue will be solved by injecting large quantities of water in the flowline (from 1.5 to 4 times the volume of produced oil) so that water is the continuous phase in contact with the wall, which reduces significantly the pressure drop. In the export line, the viscous crude oil will be blended with a light crude oil to obtain a reasonable mixture viscosity allowing its export over a long distance.  

There is potentially another method, which consists of injecting a small quantity of water (about 1/10 of the volume of produced oil) to transport the viscous crude oil in a “core-annular flow” mode. In this oil-water flow regime, a film of water flows around a core made of viscous oil. The advantage is that water lubricates the viscous oil core, and the pressure drop becomes equivalent to the case where a single-phase oil is transported with the viscosity of water. Also, a much smaller quantity of water is required compared with the concept retained for the Tilenga field. It makes this method attractive, because the reduction of the injected water flow rate reduces the pipe diameter of the flowlines and the size of the water injection pumps. However, it was not retained for the Tilenga project, because the physical mechanisms involved are not sufficiently understood. For instance, we do not know what oil and water flow rates are required to form a stable film of water around the viscous oil core, since in pipes with a small inclination, gravity tends to drain the water film from the top to the bottom of the cross-section.  

In this 18-months post-doc, we want to study core-annular flow by numerical simulation to understand the physical mechanisms at play in maintaining the water film around the circumference of the viscous oil core. Preliminary simulations were performed by a former postdoctoral researcher supervised by Dominique Legendre. We even have found a possible new explanation for the stability of the water film.