Operational strategy

Our drilling plan for Expedition 326 (Fig. F4) was to run a mudmat and a reentry assembly without the guide horn to the seafloor and jet in 36 inch conductor casing to 60 mbsf. After the casing angle had been confirmed by remotely operated vehicle (ROV) to be within 1.5° of vertical, the bottom-hole assembly (BHA) would be exchanged to a 26 inch drill-ahead assembly.

Using the 26 inch drill-ahead BHA, the hole was to be extended to at least 800 mbsf. Wiper trips were to be performed until no tight spots were observed, after which the ship would prepare for running 20 inch casing in the hole.

The 800 m 20 inch casing string was to be drifted to the site and have four ropes attached to it to reduce vortex-induced vibration (VIV) if current was strong. After cementing, the ROV was to dive with a corrosion cap to suspend the hole for future operations.