Abstract

Every human activity in the offshore Arctic, or anywhere offshore for that matter, emits some level of sound into the marine environment. Depending on intensity, and to some extent frequency, underwater sound can be a nuisance or even physically harmful to marine life.

The indigenous people of the Arctic Coastal Plain in Alaska depend on subsistence hunting of marine mammals for food and as an intrinsic part of their culture. Many have expressed concern that underwater sound from oil and gas industry activities may alter the behavior of these animals and make subsistence hunts more difficult or even permanently deflect the animals away from traditional hunting grounds. Understanding underwater sound and developing effective mitigation measures is important for operating in the Arctic marine environment.

This paper presents a brief discussion of underwater sound, regulations governing underwater sound from oil and gas exploration activities, practical implication of those regulations and outlines Shell's research program aimed at understanding underwater sound emitted by drilling operations offshore Alaska. Also presented are the concepts being developed to mitigate that sound. Although the research has been directed specifically at Alaska it is broadly applicable to other Arctic regions.

Introduction

Shell's objective in Alaska is to find and develop commercial hydrocarbon resources in the Chukchi and Beaufort Outer Continental Shelf. As with all Shell ventures, the company maintains high operational and social performance standards that will bring, with exploration success, economic benefits and new opportunities to communities across Alaska and the Northwest. Since returning to Alaska in 2005 Shell has embarked on an extensive field data acquisition, R&D and technology maturation effort aimed at supporting exploration and future development. This paper focuses on Shell's R&D program for mitigating underwater sound.

Every human activity in the offshore Arctic, or anywhere offshore for that matter, emits some level of sound into the marine environment. Depending on intensity, and to some extent frequency, underwater sound can be a nuisance or even physically harmful to marine life. Marine sound has been an ongoing issue for offshore oil and gas activities, primarily for seismic operations but also for construction and pipelaying activities in sensitive areas such as offshore Sakhalin Island, Russia. In seismic operations the concern is possible hearing damage to marine mammals and fish that are too close to the air gun arrays used. In Sakhalin the concern is disturbance of feeding behaviors of the endangered Western Grey Whale. In both cases industry and regulators have developed mitigating procedures to ensure minimum impact on health and behavior of marine mammal species. This paper describes efforts Shell is making to mitigate effects of marine sound from floating drilling rigs in Alaska. While the primary focus is Alaska, the results of this work is broadly applicable to other Arctic regions.

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