The Prelude gas field – located in the Browse Basin, north-western Australia, 260 nautical miles from the port of Broome, WA – was selected for the implementation of a revolutionary technology for stranded gas reserves.
The wells drilled and completed in this field are intended to feed the floating liquefied natural gas facility (Prelude FLNG) for the next 25 years, so integrity, robustness and equipment reliability were key issues in their construction. The field development plan consisted of seven high-rate, high-angle wells drilled in batch mode using a semi-submersible.
It very quickly became clear that the lessons captured during the vertical exploration and appraisal phases were insufficient for high-angle directional development wells. While the offset information was important, it did not address the intra-reservoir challenges (i.e. fractures, loss zones), wellbore instability, string vibration, stick-slip, high torque and drag, or reduced operational mud weight window.
This paper presents the measures implemented to mitigate those challenges. It also addresses the enablers that allowed the successful delivery of this project.
Prelude was the first project in the Browse Basin to drill horizontal wells.
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