Matthew Guite, Director of Subsea, Pipelines and Risers with newly-formed engineering consultants – Theon Limited – underlines the level to which the offshore industry can openly confront and alter its approach to subsea pipeline and flow line design.
Pipeline engineering is commonly seen as fulfilling the role of “stitching things together”, however within this specialism there are a host of technical considerations that must be carefully thought through and will vary dramatically from project-to-project. As such there is ample opportunity to challenge the status quo when it comes to subsea pipeline design.
The topic of “silo engineering” continues to present a major hurdle in ensuring optimum operational output. This type of approach leads to a general lack of cohesion across the project with little consideration when it comes to understanding how reservoir, surface facilities and subsea pipelines interconnect and the vitally different roles they play must be understood from the outset. This presents an opportunity for re-examining and fully integrating project management.
Prevalent Industry Challenges and Opportunities
As the distance of large-scale offshore tiebacks continues to extend, this presents a range of fresh challenges in terms of pipeline design. As pipelines and flowlines are custom designed, this provides opportunities for re-thinking during the concept, front-end and pre-feed stages of a project. This early investment in overall system design will help avoid nominal design ratings and “standard” designs – which can result in over design – a problem which is all too common.
Pipelines fulfil a vital role in transportation and there are a number of ways in which smarter thinking and well thought out, simple but clever designs could benefit firms’ global operations and output.
Getting it right at these early stages will pay dividends in the long run. Firstly, productivity would benefit from a more holistic approach to and understanding of flow assurance results. Flow assurance is a vital step in the design process, but needs at all times to be grounded in reality and the information used to further the design, not be the design itself.
Equally, as much as cutting corners and over design can cause its issues – over-conservatism in pipeline design can restrict and limit the level of production within the oil and gas industry. By exploring design liberally during the concept phase, the maximum potential of pipelines can be achieved, thus also resulting in reduced expenditure associated with post-build alterations.
A key industry challenge is the greatly reduced number of engineers with 10 to 25 years of experience, due to drastic cut backs in recruitment of graduates during the 1990s. This is impacting on design work, where lack of experience is being felt and historical procedures are still in use, which maintains a certain spread of experience within a design team that is no longer there.
By fully exploring options and challenging the design data a project manager can have confidence in the design process, using the results to demonstrate that the design has been sufficiently reviewed and contested. This ensures that the pipeline and overall system design is optimal. People and knowledge are vital parts in the pipeline design process, as despite the fact that no two projects are the same, an identification of a robust pipeline design is of primary importance.
Life of field design is a major consideration in the subsea pipeline design process. Subsea engineering and surface facilities should work together due to the specific and custom nature of each project. There is no “off-the-shelf” blueprint for such projects and as such it is imperative that there is a strategic approach to the current and future needs of a pipeline. Any ill-conceived planning will have a massive cost implication further down the line, as making changes during the early design phase is significantly more cost-effective than when subsea equipment and pipelines have been fully designed and installed.
There are also a range of additional pipeline factors that will influence the pipeline design; such factors include high pressure, high temperature and fluid characteristics. With variances in flow highly likely over field life, this also has a significant subsequent bearing on the design of subsea pipelines.
Current market trends mean that as oil and gas discoveries are made in more remote areas of the world pipelines must adapt to these surroundings, whilst maintaining a constant and reliable level. Consequently, there is a fundamental requirement for firms to conceive a methodical and wellconsidered design plan that takes temperature range and changes across the life of field into account. A lack of understanding and experience in this area can lead to a severe lack of asset integrity, reduced flow assurance, corrosion, over-stressing and buckling – all costly maintenance jobs to have to correct or retrofit further down the line.
Installation Cost Benefits
Despite the fact that much subsea pipeline design is carried out during the front-end and pre-feed stages of the project, the major cost element of the project is during the installation phase. Much of this cost comes from vessel and material expenditure – with installation alone commonly absorbing as much as half of the project costs saving time here is vital.
Greater consideration of materials and utilising experience during the design phase needs to be viewed as time well spent rather than delaying the proposed project start date. There is a knock-on effect on any irregularities as suitable design has the ability to maximise vessel capacity, the reel-ability of pipelines and aid in selection of the most appropriate materials for the project.
With each offshore pipeline installation typically costing firms millions of dollars, a 10 to 20 percent saving has a substantial impact on capital expenditure (CAPEX). Such measures will ensure that firms continue to operate as cost-effectively as is feasible on global projects, anywhere from oil wells in the North Sea to as far afield as gas fields off the coast of Western Australia. Ensuring and re-considering all possible design options in the first instance can achieve an optimum level of pipeline efficiency and integrity.
Future of Pipeline Design
The future of pipeline design will continue to evolve in forthcoming years, both in terms of process, materials and planning. As composites and plastics come into more common use, the need to appraise the subsea pipeline design basis will become increasingly crucial. It has also been suggested that the topical issue of non-metallic pipelines and connection systems other than welding will also aid in the advancement of pre-emptive subsea pipeline design process.
However, firms must evaluate the current exceptional safety record of dependable materials against the reduced capital expenditure (CAPEX) associated with these upcoming composites and plastics.
With company reputation management being prime in today’s 24/7 media culture – the potential repercussions of a leak could be catastrophic to brand, people, and environment. As carbon fibre, plastic / steel composites, fibreglass, and other reinforced systems become verified and more widely accepted this material advancement remains at an embryonic stage.
Another key issue moving forward will be that of proactive design review within a project lifecycle. A shrewder approach in the early design phases will continue to allow for nominal design features to be filtered out before projects are set in stone.
Design will continue to have a vital role in the rethinking of projects and the heart of efficient project management lies with a robust design basis. As the distance of pipelines continues to extend and the demand for flow increases, there will be a continued requirement for design to encompass whole fields and the strategic requirements of these fields.
Maintaining the “Pipeline of Talent”
Moving forward, the well-documented skills shortage within the oil and gas industry will also have repercussions for the way in which firms can efficiently design subsea pipelines. Engineers with over 25 years of experience and consultancies are already seeing a significant rise in the number of specialist pipeline design projects they are being requested to assist in developing.
The involvement of more experienced engineers can also help to ensure thorough design review processes and more phased stage gate planning. In many cases this is worthwhile, due to the outcome of a robust design, increased cost savings, greater quality control, and more streamlined plans.
A constructive take on the skills gap is that it offers the global oil and gas industry an opportunity to engage in knowledge-transfer. This exchanging of key knowledge helps to ensure that core expertise, such as pipeline design, are retained by the sector. However, this is not a short-term goal and the knowledge of consultancies will continue to be vital to the advancement of subsea pipeline engineering and design in future years.
There is a considerable opportunity for current and future oil and gas production to prosper as a result of taking the correct steps at an early stage, to ensure efficient and robust subsea pipeline design. Subsea pipeline design can aid production in achieving an optimal level (and cost-effectiveness) by considering the following factors:
- High Pressure, high temperature, fluid characteristics, and highly variable flow over field life and the subsequent impact on design.
- Better understanding of what flow assurance results mean to the design.
- Requirements to challenge the design data provided and its robustness.
- Over-conservatism in design and not achieving maximum pipeline efficiency.
- Consideration of life of field design and the link between surface facilities and subsea engineering.
- Pipeline and subsea structures installation – the large cost needs to be considered early in the design process.
- Ensuring each end is optimised. Considering the whole system including the subsea, pipeline and topsides all working to the best effect.
- Project costs and impact of design from the start – on installation, capacity of vessels, reel-able pipelines and material choice.
- The future of pipeline design, in terms new materials – composites and plastics.
- The importance of maintaining a talent pipeline and increased efficiencies associated with utilising the skills of more experienced engineers, especially in early stages and at key points.
By challenging these core issues, and taking an impartial analysis by means of utilising an external consultancy, firms can expect to trim a significant sum from project expenditure. Moving forward firms will have to remain openminded to not only the imminent needs of the pipeline, but also the long term potential design requirements of the project.
Over-engineering is costing the global pipelines industry millions of dollars per project with extended costs from more long distance subsea tiebacks. Being prudent towards maximisation of flow efficiency will see continued success into future generations.
Published in Scandinavian Oil-Gas Magazine No. 1/2 2013
Matthew Guite has over 25 years’ experience in pipelines, field developments and facilities design, previously working for JP Kenny on projects throughout the world. He has experience of working in a range of engineering stages, from concept design through to the eventual commissioning of pipeline systems.