Abstract
AbstractA new, modified version of the cable-suspended Ice and Bedrock Electromechanical Drill (IBED) was designed for drilling in firn, ice, debris-rich ice and rock. The upper part of the drill is almost the same for all drill variants and comprises four sections: cable termination, a slip-ring section, an antitorque system and an electronic pressure chamber. The lower part of the IBED comprises an auger core barrel, reamers, a core barrel for ice/debris-ice drilling and a conventional geological single-tube core barrel or custom-made double-tube core barrel. First, the short and full-scale field versions of the IBED were tested at an outdoor testing stand and a testing facility with a 12.5 m-deep ice well. Then, in the 2018–2019 summer season, the IBED was tested in the field at a site ~12 km south of Zhongshan Station, East Antarctica, and a ~6 cm bedrock core was recovered from a 198 m-deep borehole. A total of 18 d was required to penetrate the ice sheet. The retrieved core samples of blue ice, basal ice and bedrock provided valuable information regarding the Earth's paleo-environment.
Highlights
To resolve various drilling limitations and problems, such as logistical difficulties presented by heavy, power-hungry conventional drilling rigs, an advanced drilling system, i.e. the electromechanical cable-suspended drill, was developed in the 1940s
The modules of the Ice and Bedrock Electromechanical Drill (IBED) can be changed for drilling in firn, ice, debris-containing ice and bedrock, which allows three different tasks to be accomplished: (1) auger drilling in the upper snow– firn layers with sequential reaming for casing installation, (2) coring in solid and debris-containing ice with near-bottom fluid circulation and (3) bedrock-core drilling (Fig. 2)
In modules for drilling with liquid, the shaft from the motor connects to the gear reducer for rotation of the core barrel and connects directly to the input shaft of the pump. This allows the installation of two different types of centrifugal pumps, depending on the drilling conditions: an SPK2-23/23 type with a nominal flow rate of 33.3 L min−1 and an outlet pressure of 0.65 MPa or an SPK4-11/11 type with a nominal flow rate of 66.7 L min−1 and an outlet pressure of 0.33 MPa. Both of these are vertical multistage immersible Grundfos SPK pumps with outer diameter (OD) of 100 mm, which are designed for pumping cooling lubricants for machine tools, condensate transfer and similar applications
Summary
To resolve various drilling limitations and problems, such as logistical difficulties presented by heavy, power-hungry conventional drilling rigs, an advanced drilling system, i.e. the electromechanical cable-suspended drill, was developed in the 1940s. Since the first CRREL drill was implemented, at least six different electromechanical drills for fluidfilled boreholes have been designed in the USA, Denmark, Russia, France, Germany, Switzerland and Japan for deep-ice drilling, e.g. ISTUK (Gundestrup and others, 1984), KEMS (Kudryashov and others, 1994), PICO-5.2′′ (Stanford, 1994), JARE (Takahashi and others, 2002), Hans Tausen (Johnsen and others, 2007) and DISC (Shturmakov and others, 2007). Three related papers describe the general concept of the drilling rig (Talalay and others, 2021), auxiliaries (Fan and others, 2021) and control system (Zhang and others, 2021)
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