Deep Water FPSO and Subsea Facilities - Installation, Hook-up and Commissioning in Schiehallion on the UK Atlantic Margin
Authors: Dick M. , Sen P. , Metcalf P. 
Published: October 2008

The Schiehallion subsea facilities are comprised of a network of twenty nine subsca wells, five drill centres, twenty three flowlines and umbilicals tied back to an FPSO, moored with fourteen mooring legs secured by suction anchors in 400m water depths West of Shetland, UK. This paper describes the challenges faced and overcome in installing the subsea facilities, mooring the FPSO and in hook-up and commissioning of the subsea production, water injection, gas lift and gas disposal systems. The paper also reviews the status of subsea intervention activity required to manage production and injection.

Introduction

Installation of the Schiehallion field subsea facilities presented challenges in dealing with the environmental conditions, solving technical problems and meeting an accelerated work schedule. The field infrastructure comprising risers, pipelines, umbilicals, manifolds, connecting jumpers and the FPSO and it's mooring system were installed during 1997 and 1998 and First Oil was produced on 29th July 1998. Hook up of Xmas trees is ongoing as the respective wells are completed. This paper presents an overview of the installation methods used including the diverless construction techniques necessary in these water depths. Further details of the Schiehallion subsea development are presented in Ref.1.

Health, Safety and Environment

The key Project Condition of Satisfaction was to meet the challenge to perform the work without:Harm to peopleDamage to propertyDamage to the environment

All aspects of HSE Management were given the highest priority, as demonstrated by the clear set of Project priorities adopted:Safety (personnel and environment)Technical integrityCost and ScheduleThis focus has been maintained throughout the Project.

Risk Management and influencing the behaviour and attitude of the workforce were recognised as the two most critical factors in ensuring the challenge was met.

In the area of Risk Management the strategy was simple;Learn from previous experience:Keep issues as simple as possible:Focus on areas of high risk. (Vessel mobilisations, known to have been a source of problems in the past, were given close attention)Involve the worldforce (including subcontractors and other BP Amoco Contractors).Begin the assessment process as early as possible.Pay careful attention to the Management of Change.Communicate clearly and honestly.

In trying to influence behaviour and attitude the project approach was as follows.

As many organisations were involved in some cases only for brief periods, a great deal of effort went into establishing a high protilc "Safety Culture" in the offshore teams. The Project focused on expectations and responsibility for HSE and its success was clearly in the hands of line management, with all personnel very aware of their roles, responsibilities and authorities in the safety arena. The constant promotion of this culture by the team leaders, the BP Amoco representative offshore and the support received from the onshore management team contributed significantly to the Project's commendable safety record.