Improvement to the efficiency of pre-salt well delivery was achieved by implementing detailed planning with cross discipline teams who developed a complete vibration mitigation program that became indispensable in critical wells, such as the ones in Ultra Deep Water Pre-Salt. For this study, it was analyzed a critical well that was drilled in a pre-salt field in Brazil, with 1700m of salt section.

This paper discusses the development and deployment of a successful drilling optimization methodology and the application of new technologies and solutions to improve the drilling efficiency in a critical presalt well. The ability to rapidly analyze conditions and respond effectively was based on multiple solutions such as: engineering simulators and workflows, vibration mitigation through surface and downhole measurements, optimization of specific energy, use of a bit reamer and an anti-stall tool on BHA to attenuate torsional vibrations, applied fluid optimization, salt creep control, real time monitoring and integrated services.

For vibration mitigation improvement it was used a specific tool to attenuate torsional vibration downhole and the fast Fourier transform software, that analyses surface parameters every second and identify the torsional vibration faster than the downhole sensors. The Mechanical Specific Energy (MSE) concept was extremely important to identify any excess of energy input that could cause damage to the downhole tools and drill string. This concept also helped to identify formation changes (anhydrite and halite), very important for casing point (geo-stopping at basal anhydrite). The use of bit reamer also showed to be a very helpful tool to keep the well in gauge and avoid salt creeping near the bit. The "Profibus" protocol was implemented to permit a real time monitoring of the pilot hole and riserless sections.

The successful implementation of this methodology depended on the integration of disciplines and professionals involved setting a common goal for all stakeholders. This resulted in the salt section being drilled with high penetration rates in only one run, identifying every formation change and responding appropriately and the ability to stop in the desired section at the top of reservoir. As a result of the drilling optimization, the total depth was reached 60 days ahead of the planned time establishing a new benchmark for the pre-salt field.

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