Agile Sub-Ice Geological (ASIG) Drill development and Pirrit Hills field project

Abstract

A new drilling system was developed by the US Ice Drilling Program (IDP) to rapidly drill through overlying ice to collect subglacial rock cores. The Agile Sub-Ice Geological (ASIG) Drill system is capable of drilling up to 700 m of ice in a continuous manner. Intermittent ice core samples can be taken as needed. Ten-plus meters of subglacial bedrock and unconsolidated, frozen sediment cores can be drilled with wireline core retrieval. The functionality of the drill system was demonstrated in 2016–17 at the Pirrit Hills, Antarctica where 8 m of high-quality, continuous granite core was retrieved beneath 150 m of ice. The particulars of the drill system development, features and performance are discussed.

Deep ice drilling, bedrock coring and dust logging with the Rapid Access Ice Drill (RAID) at Minna Bluff, Antarctica

“…As noted above, hydrofracture is a known problem, based on RAID's experience during AFT2 and AFT3, and from the experience of other polar drilling systems (e.g. ASIG drill operated by the IDP at Pirrit Hills; Kuhl and others, 2020). Fracturing of ice can occur by multiple causes, including fluid overpressure, pulses of fluid passing through the system after blockages are cleared and percussive shock from loading ice with the drill string.…”

“…Rapid penetration of the Antarctic ice sheets will allow scientists to take multiple short cores in deep ice, from the glacial bed, and from bedrock below, and to create long-term borehole observatories. As a complete system, RAID is unlike other ice-penetrating tools, although a similar drilling system optimized for transport by a light aircraft utilizes the RAID concept (Kuhl and others, 2020). It is a sled-mounted mobile drilling system capable of making multiple long (up to 3300 m), narrow (8.9 cm, or 3.5 in diameter) boreholes in a single-field season on the ice sheets of Antarctica.…”

Perspectives for development of ice drilling technology: continuation of the discussion

“…Recently, several rapid ice drilling systems have been developed and tested: the US-made system known as Rapid Access Ice Drill (RAID) (Goodge and Severinghaus, 2016); the in-situ probing of glacier ice for a better understanding of the orbital response of climate (SUBGLACIOR) probe developed at the National Centre for Scientific Research in France (Alemany and others, 2014); the Swiss Rapid Access Drilling and Ice eXtraction (RADIX) system (Schwander and others, 2014); the BAS Rapid Access Isotope Drill system (Rix and others, 2019); Agile Sub-Ice Geological (ASIG) drill (Kuhl and others, 2021), and modified Winkie Drill (Boeckmann and others, 2021). Although significant steps have been taken to achieve rapid ice drilling, the problems have not yet been fully resolved.…”

“…Field tests outside the McMurdo Station, Antarctica showed that hydraulic fracturing could occur with as little as 0.69 MPa of borehole pressure (Kuhl and others, 2021). However, this was a site with warm, stressed ice chosen only due to logistical constraints with ice properties very different from where most drilling operations would occur.…”

“…Recently, problems with drilling in the frozen subglacial environments in Antarctica have generally been solved using conventional and cable-suspended drills, even though some issues remain unaddressed. During the past several years, three bedrock cores with final depths >50 m have been successfully recovered: an ~8 m long bedrock core near the Pirrit Hills (Kuhl and others, 2021); a short, 6 cm long bedrock core at the flank of the Dålk Glacier near the Chinese Zhongshan Station in the Larsemann Hills (Talalay and others, 2021); and a bedrock core slightly longer than 2 m, at Minna Bluff. However, because of basal melting, the frozen bed probably constitutes <25% of the Antarctic (Bockheim and Hall, 2002) and Greenland (MacGregor and others, 2016) ice sheets.…”