Multiplexed electrohydraulic (EH) control systems have been successfully deployed in significant numbers around the world since the 1980s. Supportability of this older standard of subsea equipment, however, has become increasingly problematic, especially where field life is now being projected well beyond the original design life of the installed system. Existing facilities are being used more and more for marginal field tiebacks and natural extensions to maximise the economic benefit of these facilities, which can only be realised in a number of cases by the introduction of modern control and instrumentation technology. By implementing effective technology insertion solutions, not only do operators gain a step reduction in supportability (obsolescence) risk, but they also gain the ability to apply current day techniques, sensors and support tools to improve efficiency and reliability and enhance oil recovery rates.

This paper analyses the opportunities that can be exploited with the implementation of technology insertion and discusses some options available to operators. Each of these older fields has developed its own characteristics since its original deployment and thus will have a unique view forward for the rest of its life. Recognising this, the paper presents some examples of standard Brownfield options and packages that can be assembled into a complete solution for any mid-life update requirement. Finally, a recent contract, which typifies the successful embodiment of this approach, is discussed to demonstrate the improvements in operator value that can be realised.

Drivers for Brownfield Upgrades

Many of the older oil fields around the world based on multiplex EH control systems have been installed and functioning since the 1980s and 1990s. Early deployments of EH multiplex controls technology - BP's Magnus field and the Shell Underwater Manifold Centre (UMC) - both came on-stream in 1983. These early systems employ technology that was then in widespread use in high reliability/low volume industries (e.g. aerospace) and had a typical field life expectancy of 15–25 years. Now 2010 has arrived, the initial 15–25 years life has expired and the original "outside possibility" for the fields to be extended by many more years has become a reality in a significant number of cases. In a recent survey, GE Oil and Gas determined that of most of its older active fields (pre-2000), not one was due to be fully decommissioned prior to 2015 and most fields were predicting at least another 10–15 years of operation.

Driving this life extension is the need to extract more oil from existing facilities due to the lack of major new fields in easy-to-access areas, and the time and cost of bringing on-line difficult fields in different areas of the world. Exploiting existing infrastructure and developing smaller pockets of proven reserves are making more economic sense in today's financial and political climate, especially with new technology that is now available. Typical subsea fields may have only recovered 35 percent of available hydrocarbons, compared to 55 percent for topsides and land-based facilities, so the opportunity to increase this rate by even a small amount

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