Materials & Corrosion exam question
(a) (i) How would you measure the tensile properties of a material (2)
(ii) Explain what the terms elastic limit and ultimate tensile stress mean (2)
(iii) Using a sketch show how you would determine the yield stress in a material that does not show a definite yield point (3)
(b) Gas with 3 mole% CO2 and 1 mole% H2S will be produced from a well through a carbon steel (L80) tubing at 100 bar and 100°C. You are conducting a corrosion assessment.
(i) What is the dominant corrosion regime and why? (2)
(ii) Name three possible corrosion mechanisms that could occur because of the H2S (3)
(iii) How can you reduce the risk of the potential corrosion mechanisms you have identified in b(ii) (3)
(iv) What specifications should I use to assess the suitability of the tubing material for the application. (2)
(c) For the design of a seawater injection completion you have been asked to specify the well completion materials based on lowest possible cost and no workovers. The seawater will be treated to reduce the oxygen content to <10ppb but given the experience with water treatment on the platform there is an expectation that there will be regular excursions >1ppm oxygen. The maximum design temperature for the injected seawater is 35°C. For the following components give your preferred materials selection and explain why:
(i) Wellhead tree (2)
(ii) Tubing hanger (2)
(iii) Tubing (2)
(iv) Sub-surface safety valve body (2)

Question:
(a)
Sketch a tensile stress-strain curve and explain its main features. (6)
Why is the yield stress important in design? (1)
Explain the term “toughness” and name 2 practical methods for determining the toughness in steel. (3)
(b)
A carbon steel tubing will produce gas with 3 mole% CO2 and 1000ppm H2S at 100 bar. You are conducting a corrosion assessment.
(i) What is the dominant corrosion regime and why (2)
(ii) Name the possible corrosion mechanisms that could occur (3)
(iii) How can you mitigate the potential corrosion mechanisms (3)
(iv) What specifications should I use to assess the suitability of the tubing material for the application. (2)
(c)
(i) In what conditions is microbial induced corrosion (MIC) a threat? (2)
(ii) How can you mitigate MIC? (2)
(iii) In a well completion where is it most likely to occur? (1)

Materials &amp; Corrosion exam question (a) (i) How would you meas...

Materials & Corrosion exam question (a) (i) How would you meas...