Conflicting views co2 corrosion models, corrosion inhibitor availability philosophies and the effect on subsea systems and pipeline design.pdf

SPE 109209 Conflicting Views: CO2 Corrosion Models, Corrosion Inhibitor Availability Philosophies, and the Effect on Subsea Systems and Pipeline Design
J. Marsh and T. Teh; Ionik Consulting/JPKenny Caledonia

Copyright 2007, Society of Petroleum Engineers This paper was prepared for presentation at Offshore Europe 2007 held in Aberdeen, Scotland, U.K., 4–7 September 2007. This paper wasselected for presentation by an SPE Program Committee following review of information contained in an abstract submitted by the author(s). Contents of the paper, as presented, have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material, as presented, does not necessarily reflect any position of the Society of Petroleum Engineers, itsofficers, or members. Papers presented at SPE meetings are subject to publication review by Editorial Committees of the Society of Petroleum Engineers. Electronic reproduction, distribution, or storage of any part of this paper for commercial purposes without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not morethan 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of where and by whom the paper was presented. Write Librarian, SPE, P.O. Box 833836, Richardson, Texas 75083-3836 U.S.A., fax 01-972-952-9435.

Different national authorities also have varying approaches to these issues. This results in designs that would be deemed as entirely acceptable foroperation in one area of the world, but which would be considered as unsafe for operation in another. One comparison that can be made is the effect on developments within the UK and Norwegian sectors of the North Sea, and will be discussed later. This publication discusses the nature of these influences, and the effect on subsea system materials selection and corrosion allowance. It also discusses theconceptual conflict between what can be designed for in theory, and what experience tells us has actually been achieved in practice. Finally, it discusses the approach that Ionik Consulting would take in formulating solutions to these issues.

Abstract This publication examines the influence of different corrosion models, corrosion availability philosophies, corrosion control philosophies andstandards on materials selection and corrosion allowance design criteria for subsea systems and pipelines. These differ enormously from operator to operator and national authority to national authority. The result is that for the same nominal environmental conditions, pipeline and subsea systems designs can vary enormously, depending on who is the client and where the facility will be situated.Also, it results in designs that would be deemed as entirely acceptable for operation in one area of the world, but which would be considered as unsafe for operation in another. This publication discusses the nature of these influences, and the effect on subsea system materials selection and corrosion allowance. It also discusses the conceptual conflict between what can be designed for in theory, andwhat experience tells us has actually been achieved in practice. Finally, it discusses the approach that Ionik Consulting would take in formulating solutions to these issues.

Corrosion Modelling Many corrosion modelling packages now exist. These range from in house operator developed models such as Hydrocorr (Shell) and Cassandra (BP, with other non BP variants), to industrial commercialpackages such as the Honeywell/Intercorr Predict 4.0 software, university developed models such as Multicorp (University of Ohio), and corrosion models presented in the form of national standards such as NORSOK standard M-506. A number of these models are conceptually based around the semi-empirical work of DeWaard, Milliams and others (1-3), with modifications to a lesser or greater extent. This...