Deep drilling at Vostok station, Antarctica: history and recent events

Abstract

Deep drilling into the ice sheet at Vostok station, Antarctica, was started by specialists of the Leningrad Mining Institute (since 1991, St Petersburg State Mining Institute) in 1970. Five deep holes were cored: hole No. 1 to 952 m; hole No. 2 to 450.4 m; hole No. 3G (3G-1, 3G-2) to 2201.7 m; hole No. 4G (4G-1, 4G-2) to 2546.4 m; and hole No. 5G (5G-1) to 3650.2 m depth. Drilling of hole 5G-1 is not yet complete. The deep drilling at Vostok station has had successes and problems. All the deep holes at Vostok have undergone at least one offset drilling operation because of problems with lost drills. These deviations were made successfully using a thermal drilling technique. Several drilling records have been achieved at Vostok station. The deepest dry hole, No. 1 (952 m), was made during Soviet Antarctic Expedition (SAE) 17 in 1972. The deepest fluid-filled hole, No. 5G-1, made by a thermal drill (TBZS-132), reached 2755 m during SAE 38 in 1993. The deepest fluid-filled hole in ice, No. 5G-1, was drilled with a KEMS-132 electromechanical drill and was stopped above Vostok Subglacial Lake at 3650.2 m depth during Russian Antarctic Expedition (RAE) 51 in 2006.In the summer season of the 15th SAE, the first drilling shelter was constructed on two steel sleds (Fig. 3), providing a work area measuring 15 Â 2.9 Â 2.5 m. A 9.7 m round tower, measured from the top of the hole, was constructed in the center of the work area and wrapped in rubberized cloth for protection ( Fig. 4).

Analytical constraints on layered gas trapping and smoothing of atmospheric variability in ice under low-accumulation conditions

“…The ice core analyzed in this study is the 4G-2 core drilled at Vostok, East Antarctica in the 1980s (Vasiliev et al, 2007). Measured depths range from 895 to 931 m, with a cumulative length of 27.5 m due to several missing portions in the archived ice at Vostok station.…”

Twenty Years of Drilling the Deepest Hole in Ice

“…After an eight-year hiatus, this hole was reopened in the summer 2005-06 (Vasiliev et al, 2007). A new geometry of cutters for penetration of "warm ice" improved the drilling process.…”

“…All attempts to recover it failed, and operations did not resume before December 2008. A new deviated hole was drilled using thermal directional drilling to bypass the stuck tools (Vasiliev et al, 2007). The new deviated Hole #5G-2 was drilled without using any special whipstock because the drill bit is usually pushed into a vertical position.…”

Extension-Type Pulling-and-Running Gear for Investigations of Subglacial Lake Vostok

“…The first stage assumes drilling a 138-mm borehole down to the depth of 1 meter to the borehole-Lake Vostok boundary using a regular mechanical drilling assembly [5,6,7] (Fig. 1a).…”

“…1b). It is intended to use a mechanical reamer mounted on a mechanical drilling assembly to perform this operation [6,8].…”