Abstract

The Statfjord Field has produced about 635 million Sm3 (four billion bbl) of oil and exported 68 billion Sm[3] of gas since the production start in 1979. Currently, the field is in its tale production, producing at an oil rate of approximately 20,000 Sm[3]/d, which is about 17 per cent of plateau production rate. Improved recovery and thereby extended production life of the Statfjord Field is now to be obtained by changing the drainage strategy from pressure maintenance to depressurisation. About three million working hours are planned for in connection with the upgrades required to extend the lifetime of the Statfjord Field by approximately 10 years. The production will continue and be optimised during the upgrading and changed drainage strategy.

Real time data transfer from offshore to land enables support of drilling, well intervention and production operations in an efficient manner. New work processes were required in order to facilitate remote support as well as quality control of production logging, measurement while drilling, drilling parameters, geology structures, well completion, process adjustments and production optimisation. In addition, onshore engineering support results in a much better utilisation of engineering resources. Visualisation in onshore/offshore meetings (twice a day) has enhanced a common understanding and made the work process integrated. Careful planning of adjusted work processes and making an energising involved personnel were the most important issues in order to achieve results and drive the changes.

The results so far are successful and the conclusion is a continuation of the project and an expansion of the involved professional disciplines to gain increased quality and time efficiency of the offshore operations.

Introduction

The Statfjord field is a Norwegian offshore oil field with three concrete platforms (Figures 1 and 2). The old facilities produce with a high regularity of 95 per cent, mainly due to a comprehensive maintenance programme. The field has been an oil field and is now being converted to a gas field by decreasing the reservoir pressures and producing the mobilised and cumulated gas (ref. 1). About three million working hours are needed for the upgrades required to extend the lifetime of the Statfjord Field until the year 2018 (Figure 3). In connection with converting the old oil field to a gas field, reducing OPEX is a matter of necessity. Engineering personnel resources are limited. By moving engineering support from offshore to land, a much better utilisation of these personnel resources would be achieved.

A development strategy and reservoir management have been parts of established work processes and best practice. Constant focus on enhanced quality of the decision basis is partly the reason for the very high oil recovery factor of 65 per cent (ref. 2–4).

Previous work processes based on paper flow and calculations were slow. Analyses were made faster after the introduction of computers. Now the work process must handle utilisation of real time data (ref. 5). Automatic monitoring, real time surveillance control, data storage for post examinations to learn from experience and remote interpretations were all important elements in increasing quality and reducing OPEX. Statoil's strategic plan is to be among the leading operators in integrated operations (IO) within 2007. This plan is forwarded as a corporate initiative from the CEO (Figure 4). Hence, real time data management became a strategy for Statoil (ref. 6).

When it became possible to extract real time data from main servers, a new and even more beneficial opportunity was revealed. Multidisciplinary teams could remove bottlenecks and optimise the value chain from reservoir development via the process facility and transport down to the oil and gas trading. Gathering multidisciplinary teams irrespective of geography also enables working processes that in turn will lead to better, faster and safer decisions.

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