Modern Casing Design Optimization
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- Studentoppgaver (TN-IEP) 
“Working Stress Design” is the most used casing design method and has been for many years, on the Norwegian continental shelf as well as all over the globe. It is a simple method which in essence comprises of calculating the differential pressure on a casing wall in given well conditions with regard to specific scenarios that can be expected to occur in the well. Every casing has its own strength with regard to burst, collapse and tension and by comparing this to the calculated load, a design factor is obtained which is required to surpass statutory safety factors imposed on the company by nations, the company itself, or by other regulatory agencies. There exist fairly advanced casing design programs on the market which require a great amount of input variables and usually at a cost which equals their advanced nature. In this thesis a casing design program has been designed in excel with the main goal of being as simple as possible with as few as possible input variables needed, and still provide the user with the required load calculations as well as other relevant information. It has only one page where the user is needed to interact with the program, and it presents all the relevant results in one page. All the calculations and lookup functions are conducted in the background to only provide the user with the information needed. The program presents results on design factors, weak point in the well, full or reduced well integrity and kick margin values for each specific casing string or liner. The program has been tested in case studies for two different wells obtained from the industry and has provided satisfactory results with regards to the mechanics of the program. Some limitations due to a different casing string setup in the second well has been identified and this provides an opportunity improve the program in order to handle non-standard or modernized casing string compositions.
Master's thesis in Petroleum engineering