To measure the relative motions of GAIA's telescopes, the angle between the telescopes is monitored by an all Silicon Carbide Basic Angle Monitoring subsystem (BAM OMA). TNO is developing this metrology system. The stability requirements for this metrology system go into the pico meter and pico radian range. Such accuracies require extreme measures and extreme stability. Specific topics addressed are mountings of opto-mechanical components, gravity deformation, materials and tests that were necessary to prove that the requirements are feasible. Especially mounting glass components on Silicon Carbide and mastering the Silicon Carbide material proved to be a challenge.

A North Sea gas well was drilled and completed in 2000. Soon after the well was put in production, sand was also produced and became a major problem. Since the process system on the satellite platform was not capable of handling the sand, sand screens were installed in the well to prevent any further sand production. During the following years the sand screens became completely blocked and production ceased. The well was shut in for the next 10 years until a thru-tubing recompletion program was executed: milling out the permanent packer, fishing and retrieving the existing sand-screens and installing 130 m of new screens in a live well, all with 2 3/8–in. intelligent coiled tubing (CT). Intelligent CT interventions are operations in which rea-time downhole data is used to improve operational efficiencies. The realtime downhole data that can be obtained during CT operations include accurate depth correlation, pressures, differential pressures and temperatures. In combination with a realtime downhole camera, the high quality of data proved to be very valuable during the decision-making process, since the actual downhole situation can be assessed while many uncertainties are being eliminated. The visuals obtained by the camera played an important role in the choice of fishing tools and in discovering the exact position of fish and packer elements. This paper describes the challenges, the operational execution and the lessons learned from the recompletion project. It also explains in detail the operational aspects of the intelligent CT and how it was beneficial to the successful execution of the intervention program. Following the successful operation, the well was produced through the well test package on board the support jack-up, and production figures exceeded expectations. After this initial well, interventions in several more wells followed, whereby thru-tubing sand screens were installed with use of intelligent CT.