Drilling in the Company of Herrings, Lobsters, Minke Whales, Bottlenose Dolphins, Protected Birds and Fishermen
Authors: Wall R. , Rapach J. , Ellis C. 
Published: December 2007

Premier Oil, and their partner Amerada Hess Limited, drilled, completed and tested the 11/24-1 exploration well in the inner Moray Firth during September through November of 1996. This well was one of the most environmentally sensitive wells to be drilled in Great Britain to-date. The inner Moray Firth is of special scenic, environmental and historic interest; commercially sensitive due to fishing, and a spawning ground for Herring and other exploited species of fish. It is renowned for its abundance of protected birds and sea life including Minke Whales and Bottlenose Dolphins.

Under the "Well Design and Construction Regulations" applicable to the United Kingdom Continental Shelf since June 1996, and following discussions with the relevant authorities, special environmental groups and the local village community of Lybster which was 3km, and in line-of-sight of the location, the well was permitted, drilled, completed and tested without any environmental infringements.

This case study describes the extreme environmental and commercial sensitivity of the area and the methods and safeguards employed to drill, complete and test the well from a location not permitted under the original license conditions.

Introduction

Block 11/24 was awarded to Premier Oil (as operator) and Amerada Hess Limited during the 14th Licensing Round in December 1992. Due to the environmental and commercial sensitivity of the block, the license contained a number of special conditions. These ranged from the number of rigs permitted in the block at any one time, to the appointment of a Fisheries Liaison Officer. However, more importantly, there were three key elements within the license that had a significant impact on the project as a whole.

First, was the restricted time frame in which seismic and drilling operations were permitted. These activities could only take place during the months of October, November and December. All other times in the year are recognized as spawning seasons for fish, or breeding seasons for birds and sea mammals.

Second, no drilling activities would be permitted within three miles of the coastline. This restriction had been imposed to protect the large number of bird and seal colonies that inhabit the shoreline.

Finally, drilling activities would be restricted on gravel sediments since these potentially provide some of the most prolific spawning grounds for herring in the UK.

This paper describes the high level of involvement and consultation required with the relevant government authorities and other organizations, including the local fishermen, at each stage of the project. It describes the process and methods adopted to obtain the initial 2D seismic data and a comprehensive site survey. In addition, it details the innovative methods and safe-guards employed to enable the 11/24–1 well to be drilled on the chosen location, within the three mile restricted zone.

The high level consultation, policies and practices adopted for this operation did require greater financial resources. The additional cost of the well due to the increased commitment required an estimated 15% premium on a "typical" North Sea well. However, the degree of success was directly measurable; at no time were any drilling or hydrocarbon materials discharged into the sea, even during well test operations. All geological and well test objectives were achieved without compromise to the special requirements and restrictions imposed.

Environmental and Commercial Sensitivity of the Location.

Prior to making the application for block 11/24, Premier Oil felt it was important to understand the complex environmental and commercial sensitivity of the block. Therefore, a comprehensive environmental assessment of the area was commissioned.

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