Plans unveiled to drill world’s deepest well
By PRAMOD KULKARNI
HOUSTON -- The Cutting-edge Drilling Technology session at the Offshore Technology Conference went literally off the deep end with a presentation on “Designing the World’s Deepest Offshore Well to Drill and Core the Earth’s mantle”.
Nicolas Pilisi with Blade Energy Partners provided a technology update for the Integrated Ocean Drilling Program (IODP) plans to drill the world’s deepest offshore well to core the Earth’s mantle and acquire a 1,640-ft core sample coring through the Mohorovicic seismic discontinuity into the upper mantle of the oceanic crust.
The coring of the mantle is expected to answer several fundamental questions regarding the dynamics of the Earth and its deep structures. According to Pilisi, the IODP plans to use the drillship Chikyu to drill to the mantle at one of three candidate locations in the Pacific Ocean— Cocos Plate, Baja California, and offshore Hawaii.
The main challenges as outlined by Pilisi concerned drilling with a riser in an ultra-deepwater environment with water depths in excess of 13,000 ft, drilling and coring high-temperature igneous rocks at temperatures as high as 480°F. The total cored interval is expected at 19,685 ft.
The feasibility study evaluated the current steel riser configuration aboard the Chikyu and evaluated alternative designs such as risers made of titanium, hybrid titanium-steel, as well as slim-riser and lighter buoyancy modules. The well would have a four casing sizes: 20-in., 13?-in., 11¾-in. and 9?-in., because the core drilling would be accomplished using a 8½-in. rotary core barrel.
Pilisi concluded that the offshore Hawaii location could be drilled and cored using existing technology because of reduced water depth and lower bottomhole temperature, but drilling the other locations would require the advancement of downhole high-temperature tools.