11 July 2010

A stuck drill

The effect of the glycol is seen on the core break
The bottom of the core pulled free with the help of glycol.

Since Friday night drilling has been progressing well with most runs retrieving cores of 2 m or more. After several standard runs this Sunday, the drill did, however, get stuck at the bottom of the bore hole at around 19 h. A pull in the cable of up to 2400 kg did not free the drill.

This is the first time the drill got stuck at NEEM, but at the NGRIP site the drill got stuck in the deep warm ice several times (most frequently on Sundays), and a technique to free the drill without damaging the borehole or the ice core has been developed. At 21.15 h  2.3 kg of frozen ‘glycol pills’ where dropped in the hole. Those pills sink to the bottom of the hole where they melt and dissolve ice around the drill head. A high tension is kept in the cable to ease loosening. At 23.37 h the tension in the cable lowered and the drill was free. At surface, the effect of the glycol is seen on the core break. 

An exciting Sunday evening that gave us a warning of the troubles the drilling may face in the coming weeks.

Drilling: 9.04 m, drillers depth: 2420.95 m
Logging: 10.00 m, loggers depth: 2437.73 m
Processing: bag 1394-1410 (9.35 m) 775.50 m 

What we have done today:
1. Drilling and logging.
2. Processed deep ice cores.
3. CFA maintenance and calibration.
4. Maintainance on all Picarros and the surface vapour sampling equipment.
5. Inspection of skiway.
6. Preparation of food order lists.

Ad 1. At 20:00 it was not possible to break the core after drilling a core. We pulled with 2400kg without luck. The tension was slacked to 2200 kg and at 21:00 2.3 kg of frozen glycol pellets were dropped down the hole. The frozen glycol melts at -16 °C  and thus passed most of the -28 °C  cold borehole without melting. We believe the temperature at the bottom of the borehole is around -5 °C  and these warm temperatures cause the glycol pellets to melt and act. At 23:37 just when the Sunday movie ended the drill slipped and was pulled to the surface. Why does the drill always get stuck on Sundays?? (written by Dorthe – a more professional story may follow in a few days)

Ad 4. Several of the Picarro’s also decided to respect Sunday rest and the whole day was used on repairs.

Ad 5. After 10 days of clear blue sky the skiway is so hard that you barely can see foot prints on surface.

Ad 6. Rene and Lizzie worked hard on preparing the food order for the last month. The SYSCO food lists are quite a challenge the first time you order.

Weather: Clear blue sky, winds up to 8 knots from SSE and temperatures -16 °C  to -7 °C .

FL’s Dorthe Dahl-Jensen and Anders Svensson

The volley game from Saturday continues…


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