A number of industry sources have identified the need to improve overall productivity of subsea wells through the application of monitoring and control systems in the wellbore and on the seabed. To achieve this goal, two elements must be mastered: information and measurements of key attributes of the well/reservoir productivity, and a means to change and command the process, preferably through remote-controlled devices rather than traditional well intervention.

With the advent of intelligent wells, the second element has been addressed through a variety of process control devices used at different points in the wellbore and on the seabed. However, the growth of this process was limited by the absence of effective information gathering and data transmission systems in subsea wells, which remained underdeveloped compared to other subsea hardware. This resulted in systematic information bottlenecking caused by poor connectivity between the wellbore and the rest of the subsea infrastructure.

The paper introduces a complementary surveillance system that works with existing subsea devices and highlights its role in gathering and transmitting well and subsea data reliably and in sufficient time needed to maintain optimal production. In particular, the system targets high data traffic areas in order to de-bottleneck the subsea transmission systems and provides wellbore monitoring and inflow quantification. A continuous data highway is now available to both wellbore and subsea-based measurements, leading to improved monitoring and control of the entire subsea system.

The applications and benefits of the system are demonstrated through a case study. The study discusses the role of the surveillance system in bringing the productivity index of subsea wells to be in par with the platform wells. It also demonstrates the need to rethink the flow assurance process as increasing number of distributed seabed measurements become available to the subsea industry and tie-back distances increase to make the best use of expensive host facilities.

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