The New Technological Frontiers of CO2 and Hydrogen Transportation Via Pipelines

COVID-19 pandemic is accelerating the transition to decarbonized energy systems. In this context, major Operators and Contractors are bound to promote innovation and technological development. The paper describes how this is being applied to the design of offshore pipelines that are now required to transport not only Hydrocarbons but also anthropogenic CO2 and low-carbon Hydrogen. In order to evaluate all the new technical challenges presented in designing CO2 and H2 pipelines, a state of art has been carried out and is here presented focusing on all the new technical aspects associated to the main disciplines involved in the pipeline network design. Different technical aspects (such as performances evaluation of Equation of State in CCS, Design Standards application to both CO2 and hydrogen pipelines, energy capacity of hydrogen pipelines and others) have been also analytically or numerically addressed simulating credible pipeline operating scenarios. To achieve that, an intensive engineering effort is being dedicated to the development of knowledge, engineering tools, methods and procedures that will be the basis for the execution of future projects concerning H2 and CO2 transportation and storage. A particular focus has been dedicated to offshore pipeline design both for new installation and repurposing of existing ones. In parallel, the cooperation started between Operators, Contractors, Manufacturers, Institutions and Universities, as described in the present paper, acts as a "booster" for the consolidation of knowledge and for the advancing of technology to put in place to overcome those new challenges. Recommendations are made in relation to the gaps found in experimental evidence present in literature and gaps in Standards coverage for the proper pipeline design in those new scenarios.

Global Buckling Characteristics of Offshore Bundled Pipeline System

In recent years, the global buckling assessment of offshore pipelines in High Pressure-High Temperature (HPHT) condition become increasingly challenging since more complex pipeline system arrangement e.g. pipe(s) or cable(s) is strapped onto a larger pipeline, are rapidly utilized in many areas. Yet, the detailed guideline to assess the buckle of bundles remains unclear, therefore this study will focus to investigate on a methodical and reproducible approach to analyze in-service buckling behavior of bundled offshore pipeline system. The global buckling behavior of bundled offshore pipeline system in this study is investigated using commercial Finite Element (FE) software. Two carbon steel pipelines with different diameter are bundled and the buckling behavior is studied under the influence of buckle triggers. In the actual condition, the rogue buckle trigger is generated from OOS (out of straightness) or imperfection e.g. due to laying tolerance. Varying dimension parameter such as diameter ratio between the main pipeline and strapped pipeline are considered to understand the impact of this parameter on the buckle behavior. The study begins with a comparison of the results using numerical and analytical approaches on a straight pipeline in an unbuckled condition for validation purposes. The design parameters including wall thickness, process data, and pipe-soil interaction data, are varied since it influences the buckle behavior. In addition, some design parameter such as material properties and pipeline length will be adopted from a typical offshore pipeline project and the values are fixed so the exercise can focus on the most governing parameters. Following this, two numerical modelling methods, the equivalent properties method and the connector method, are presented in this study to simulate bundled systems. With a good agreement between the analytical and numerical approach, some buckle trigger is introduced on the numerical model of the bundled pipeline so the system is able to buckle and the behavior can be evaluated further. The strain level, lateral displacement, axial feed-in and pipe integrity shall be reported in the post-buckle conditions for both main pipe and strapped pipe as per current code and standard requirement. With more reliable results of buckling assessment for bundled pipeline system, it gives technical confidence and a major saving in both Capital Expenditure (CAPEX) and Operational Expenditure (OPEX). Industry has put serious effort through various Joint Industry Projects (JIP) to develop the global buckling assessment guideline in order to ensure long term integrity operation. Although the JIP guideline is predominantly for single pipeline system, similar assessment is demanded also for bundled pipeline system which described in this study. Key findings of the assessment are presented along with an overview of the design process and the typical mitigation techniques to be considered for similar subsea pipeline projects.

Assessment of the impact of ice gouging on the Arctic marine pipeline systems

Для исследования методик оценки влияния ледовой экзарации на подводные трубопроводы проанализирована отечественная и зарубежная нормативно-техническая база в области проектирования, строительства и эксплуатации морских трубопроводных систем, подробно рассмотрены общие подходы к решению данного вопроса. Систематизирован опыт строительства и эксплуатации трубопроводов в условиях замерзающих акваторий, представлены способы их защиты от повреждений в результате дрейфа ледовых образований. Дана оценка характера формирования и особенностей распределения ледово-экзарационных форм по глубине акваторий. Показано, что существующая методология оценки воздействия ледовой экзарации на морские трубопроводы не позволяет в полной мере учесть льдогрунтовое взаимодействие. Установлена целесообразность разработки критериев для определения минимальной безопасной глубины заложения подводных трубопроводов в районах с дрейфующими льдами. Обозначены направления дальнейших исследований механизмов ледового выпахивания, деформаций прилежащего к трубе грунтового массива и поведения заглубленного трубопровода. Полученные результаты позволят дополнить существующую методологию учета воздействия ледовой экзарации на морские трубопроводы, прокладываемые в замерзающих акваториях, с целью обеспечения их безопасности и надежности. To consider the methods of assessing the impact of ice gouging phenomenon on subsea oil and gas pipelines, the authors analyzed Russian and foreign codes and standards in the field of offshore pipeline systems design, construction and operation, and also considered in detail scientific approaches to investigate this issue. Within the framework of the analysis of peculiarities of offshore pipelines operation in areas with ice gouging, systematization of experience gained from pipeline systems operation in freezing waters was carried out, and methods of pipeline protection from damages caused by drifting ice formations were considered. The assessment of ice induced gouges formation and distribution features is performed. It is shown that the assessment methods presented in current codes and standards to determine the ice gouging impact on marine pipelines do not allow to directly take into account the ice-soil interaction. The feasibility of developing criteria for determining the minimum required burial depth for subsea pipelines in areas with ice gouging is determined. The directions of further research to ensure safe and failure-free operation of subsea pipeline systems in freezing water areas are presented.