Sea Floor Impact

Drill fluids and cuttings and grout (cement) reached the sea floor during the riser installation to 6.25 m bsf, coring ahead with HQ to 57.5 m bsf and a second riser installation to 13 m bsf. After the second riser installation no drill fluid or cuttings were observed with the submarine video that exited the annulus around the riser at the sea floor. A flat cone of cuttings and cement was created on the sea floor that was less than 5 m in diameter and 0.6 m high with an approximate volume of 1.25 cubic metres.

During this phase of riser installation and HQ coring ahead a volume of 300 cubic metres of drill fluid was used comprising 17.5 tonnes of biodegradable dry mud products that was dispersed into the sea water at the sea floor. Cementing the riser used 2.2 tonnes of dry cement to mix 1.1 cubic metres of grout that was distributed in the annulus around the riser to a depth of 13 m bsf and in the sea floor cuttings. Drill fluids used after installation of the riser and sealing at the sea floor annulus were not observed exiting the sea floor in the video system field of view and were presumed to be lost to the formation.