Structural limitations of unbonded flexible pipe technology with emphasis on high pressure applications
MetadataShow full item record
The purpose of this work is to discuss the structural limitations of the unbounded flexible pipe technology, used to support offshore production activities in high pressure fields. In addition, the thesis aims to describe and analyse state-of-art design solutions and elaborates on a development of a novel simplified methodology for early fatigue severity indicator (based on the ongoing discussions carried out by Technip). The work contributes to the internship at the FlexiFrance/Technip, Product Engineering Division, Le Trait, France. The internship took place from 19th of January to 29th of May 2015. As modern drilling seeks for deeper waters and high pressure/high temperature submarine formations, the producing companies require higher standards of the production systems, increasing the operating pressure ratings up to 20 000 psi. This provokes usage of more robust materials, increasing challenges for the flexible pipe fatigue. In order to address the whole range of the flexible pipe applications within a production circuit the following basic design drivers are considered in the project: a) rough/smooth bore structures, b) sour/sweet services, c) dynamic/static applications. The work is based on Technip’s expertise; however it broadens the referential, on the independent intiative and view of the author, base to the experiences of other companies, SPE & OTC publications, UiS courses, books e.t.c.. The following methods are incorporated in the project: - Use of data simulated with Technip software (with following analysis); - Overview of the existing studies on the subject, both public and private; - Communication with UiS faculties and Technip onsite-personnel; - Review of information available on specified libraries (internet, specific literature). The most prolific results of the study are: - Overview (learning) of the state-of-art for flexible pipes use in offshore production systems; - Problem stipulation (high pressure performance, fatigue analysis); - Research for the different operational limitations (scope of assumptions for the research); - Alternatives for the flexible pipe design/future design improvements; - Proposal of a novel simplified methodology for early fatigue severity indicator (based on the structural capacities and not on the designated local fatigue analysis/finite element analysis). Major findings and conclusions are the definitions of the operating conditions for the flexible pipe in high pressure offshore areas, fatigue assessment methodology based on the results of the internship. The student has however contributed the work with: - Optimizing a Technip solution by selecting materials and structural elements of flexible pipes; - Designing the flexible pipes with Technip in-house software; - Presenting results and structural limitations; - Synthetyzing fatigue analysis reports from Technip global units; - Performing fatigue design of the flexibles based on data collected; - Proposal of a novel indicative methodology for the fatigue performance the fatigue performance.
Master's thesis in Offshore technology