The execution of survey operations is a recurrent task during both the design and operation phases of a field development. As such, developments in survey techniques and optimisation of costs vs. results are a key factor when considering the constant moving of the industry towards deeper water developments. During March to July 2000, Sonsub Ltd. developed a leading capability in this field by planning and executing one of the most challenging pre-engineering surveys of this type, involving the characterisation of the two pipeline routes for the Blue Stream Project. This project, led by Saipem as Main Contractor, involves the installation of two 24" pipelines across the Black Sea joining the coasts of Russia and Turkey. The route is characterised by long and steep slopes at both shore approaches, and by an Abyssal Plain section of 240 kilometres in a water depth of 2,150m. Sonsub Ltd. addressed the challenging survey requirements by combining their new generation ‘Innovator’ ROV technology with state of the art survey sensors and systems to provide a reliable but highly flexible solution for high specification data acquisition and seabed intervention. The Sonsub remote intervention vessel ‘Polar Prince’ provided a sophisticated operating platform, which guaranteed maximum productivity and reliability throughout the project. This paper will describe preparatory works, operating equipment spread, difficulties and problems encountered, together with the solutions and results, which contributed to the successful completion of the Blue Stream Pre-Engineering and Abyssal Plain Survey.

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