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Working on top of the world: Part 1

Hydrocarbon Engineering,

Depending on the report, the Arctic region may hold one quarter of the world’s oil and gas reserves, or even more. It is inevitable that the increasing global demand for energy will lead the oil and gas industry towards the Arctic region, one of the great frontiers of our time. With diminishing reserves in many of the mature oil and gas regions worldwide, many international oil and gas companies are making the Arctic a priority, together with the national energy companies of the countries in-region.

The fact that a large proportion of the world’s reserves are in the Arctic is testament to the challenges that need to be met in order to harvest the region’s natural resources. The oil and gas industry must tackle its extreme climate. The potential reward is balanced by environmental risks to the region’s delicate and complex ecological system. The consequences of an incident could be extremely significant. Added to this there are significant human and asset risks. Safe and reliable solutions are therefore required for energy exploration, production and transportation in the Arctic.

Challenges to investment in the region include:

  • Difficult working conditions for crews.
  • Problems from assets icing up, in terms of the operating equipment and human activity including personnel movement.
  • The remoteness of the region, at least until a significant infrastructure is established in the region.
  • Providing adequate oil spill equipment and emergency response measures in icy, inaccessible areas.
  • Potential vulnerability to climate change and the uncertainties that this may pose in terms of design conditions.

Against the backdrop of the above challenges and some historical events, society expects the highest standards of health, safety and environmental performance and is carefully scrutinising the industry’s developments in the region to make sure they are achieved.

So oil and gas developments in the offshore Arctic areas involve unique challenges. Individual and novel solutions, in some cases deviating from the norms established in the more mature regions in the oil and gas world, may be required to meet these challenges that are both economical to build and safe to operate. In the following sections, this article will explore some of the issues to be faced.

Design for ice loads

Offshore petroleum exploration has been taking place for about 50 years, yet there is still a lack of convergence as to the calculation of design ice loads for Arctic offshore platforms. Impacts from ice can generate high local pressures, causing damage or failure of small but critical areas of structures and ships. The issue has significant implications to the economic feasibility of Arctic offshore production, as well as future exploration activity.

Ice loads depend on geographical location, season, ice feature type, interaction scenario and structural configuration. Structures must be designed for rare or frequent environmental events, including interactions with sea ice and icebergs. Research on ice loads over the past several decades has improved understanding of these loads, especially for level ice conditions. However, comparative studies show that predicted loads for ice regimes vary significantly. These uncertainties often lead to conservative assumptions regarding ice loads, as well as significantly higher construction and operational costs in regions where ice ridge loads are governing.

A better understanding of all types of ice features, and the factors that affect ice loads, can help reduce these uncertainties. The establishment of an internationalstandard addressing these issues will assist in the industry taking a harmonised approach

Material issues

Subsea oil and gas infrastructure in the Arctic, such as pipelines and subsea equipment, are not necessarily considered to be in extremely cold environments; the minimum temperature at the seabed is often greater than 4 °C, which is similar to many deep ocean temperatures elsewhere in the world. Material issues are, however, relevant for structures above the surface of the water, or onshore, including the landfall area for pipelines.

For subsea pipelines, it is the installation phase of a construction project which presents the most significant challenges. Historically, most pipeline installations worldwide have utilised traditional stress-based design principles. These design applications pose few challenges in terms of pipeline material properties or requirements for weld procedure qualification. However, both onshore and offshore pipelines operating in the Arctic may be exposed to high strains. In combination with very low temperatures, this must be considered when material and weld procedures are selected and qualified for stain-based design purposes.

Control of structural integrity in the installation and operation of oil and gas pipelines is critical. The risk of fractures occurring due to presence of cracks or other defects must be tightly controlled, and appropriate safety levels must be assured. The maximum permissible flaw sizes are thus often very small for Arctic pipelines exposed to high strains.

Written John Yates, Marsh, UK, and edited by Hannah Priestley-Eaton

To read the full version of the article, please download a copy of April issue of World Pipelines.

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