Scaling Modelling for annulus environments

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Location/Division: Cambridge

NSIRC243: PhD Studentship (Sponsored by TWI Ltd) - Scaling Modelling for annulus environments 

Institution: National Structural Integrity Research Centre (NSIRC)

PhD Supervisor: Maria Eleni Mitzithra, Shiladitya Paul, John Rothwell

Application Deadline: Open throughout the year

Funding Availability: Funded PhD {roject (Students Worldwide)



Flexible pipes, are structures composed of several concentric layers of steel wires and polymeric materials. The steel provides resistance to the operational loads, while the presence of an inner and an outer polymeric sheath are chemical barriers to the production fluids and seawater respectively.  When these were introduced, their design was based on the assumption that the annulus environment, i.e. the space comprised between the two polymeric sheaths, would remain dry and non-corrosive under normal operation. However, water and CO2 can permeate into the annulus over time, creating a corrosive environment. 

Production fields with high partial pressures of CO2 and H2S, could compromise the integrity of the asset. In order to determine corrosion mechanisms, including when changes occur in the annulus, the evolution of corrosion and scale formation could serve as important indicators of the environment and the help to improve prediction of long term performance. The development of an initial model would help to predict scale formation in the annulus. An understanding of the primary environmental factors and the formation mechanisms, of the polymorphous products in annulus environmental conditions will be key to understanding the corrosion behaviour in occluded annular environments.


Project Outline

The key deliverables of the project are:

Model the precipitation/formation rate of the different phases of the corrosion scales and effect on dissolution rate of iron in CO2 -containing annulus environments

Validate the model output by comparing with existing experimental data


The project will investigate:

Effect of temperature and partial pressure of CO2

Effect of pH/solution chemistry on the scales formation rate vs. iron dissolution rate

Effect of degree of confinement on the scales formation rate vs. iron dissolution rate

Effect of gas flow rate


Some additional experimental work, using advanced surface characterisation techniques, may be required for suggesting possible improvements for overcoming the initial model’s limitations (e.g. pits’ formation, scales transformation)

In long term, this would suggest that a fully developed scales’ formation model, taking into account all affecting parameters, along with obtained experimental data, could be integrated/implemented in corrosion prediction models at the design stage, where all possible scenarios, i.e. changes, should be taken into consideration.

About Industrial Sponsor

TWI is a world leading research and technology organisation. Over 800 staff give impartial technical support in welding, joining, materials science, structural integrity, NDT, surfacing and packaging. Services include generic research, confidential R&D, technical information, technology transfer, training and qualification.


NSIRC is a state-of-the-art postgraduate engineering facility established and managed by structural integrity specialist TWI, working closely with lead academic partner Brunel University, top UK and International Universities and a number of leading industrial partners. NSIRC aims to deliver cutting edge research and highly qualified personnel to its key industrial partners.

About University

The University of Leicester is one of the UK's leading universities, committed to international excellence through the creation of world changing research and high quality, inspirational teaching. Leicester is ranked in the top 2% of universities in the world by the QS World University Rankings and THE World University Rankings. Leicester is a leading UK university, currently ranked 34th in the Complete University Guide.

Candidate Requirements

Candidates should have a relevant degree at 2.1 minimum, or an equivalent overseas degree in Physics/Chemistry, Chemical Engineering or Materials Science. Candidates with suitable work experience and strong capacity in numerical modelling and experimental skills are particularly welcome to apply. Overseas applicants should also submit IELTS results (minimum 6.5) if applicable.

Funding Notes

This project is funded by TWI and academic partners. The studentship will provide successful Home/EU students with a minimum stipend of £16k/year and will cover the cost of tuition fees. Overseas applicants are welcome to apply, with total funding capped at £24k/year. 




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