Left: RADIX drill head. Center: Remo and Jakob inspecting the drill. Right: Drill including casing material cut from near the bottom of the casing.

Producing the right chips

Talk here at EGRIP is all about chips – albeit not the ones you eat, but the small cuttings produced while drilling through the ice sheet. At the RADIX site it has now been proven that the RADIX drill can also drill polyethylene, producing black drill chips (see today’s pictures from the RADIX site). This was of course not the idea, but the drill simply cannot make it through the last cm’s of the casing and into the ice sheet itself. Hence tomorrow it is planned that the casing will be pulled up and inspected to clarify the issue. At the deep drilling here at EGRIP camp, ice chips are indeed produced, but they want to stay in the borehole instead of being nicely recovered by the deep drill. This means that we again had to interrupt the drilling and do filtering runs all Sunday to recover lost chips. This is tedious work, that is now undertaken both by 4 drillers and by 2 members of the ice core processing crew. The crews in the isotope CFA and Physical Properties labs. continues measuring samples at a steady pace. Albeit with some interruption in the isotope CFA cabin, as all power was suddenly lost to the instruments Saturday. Due to the quick reaction of the isotope crew a controlled power down procedure was followed, and when the electrical issue was fixed, all instruments came nicely back to life. Processing was done only Saturday, so Sunday the processing crew where able to do other tasks, including chips recovery, a Doppler radar test and data processing and evaluation.
Of course we also took time to have our traditional Saturday dinner – this time prepared by our Japanese colleagues (see second picture), who prepared an excellent meal for us, even including delicious plates of sushi! And on Sunday we were again treated with brunch for lunch including omelettes cooked to order by Frederik, Lasse and Lisa. We are truly getting spoiled here at EGRIP. Finally the weekend was nicely ended with celebrating Jans birthday, including the traditional Danish birthday song with imitation three instruments chosen by Jan. Quite a challenge with siren, church organ and steel drums!

What we did during the weekend:

1. 17.2 meters of main core drilled, recovery of 140 kg of chips through filtering.
2. Logging of main core from 1354.68 m to 1371.86 m.
3. Processing of EGRIP main core in the science trench, final depth: 1337.05 m.
4. Measurements in isotope laboratory, final depth: 864.05 m.
5. Measurements in physical properties laboratory to 1328.80 m.
6. Water vapour sampling and measuring.
7. Japanese snow crystal and surface monitoring.
8. Preparing for drilling at RADIX site.
9. Test of Doppler radar.

Ad 1: Drillers report for 27/6 to 8/7: After successfully running the NEEM drill electronics for 5 days due to refurbishments of the EGRIP gear section and motor, the drilling could continue with the EGRIP setup. A deadweight is installed at the top of the drill in order to improve travel speed down hole. In order to increase production rate even further, the most efficient cutting mode is to be found. This is done by changing cutting pitch, rotational speed of cutters and nature of cutters - changing one parameter at the time. During this process the electronics and motor are pushed to the limit, thus revealing the capabilities of the system. The limiting factors being the available electrical current, and the temperature of the electronic section. Traditional DML cutters are tested with pitches of 2.8 mm to 3.5 mm with cores successfully recovered. The last known working configuration of step cutters (pitch ~1.5 mm) are used in between reconfigurations. Step cutters with pitches from 2.5 mm to 3.5 mm are to be tested during the coming days. After 3 days of drilling, 14 filter runs were completed, recovering ~450 kg of slush from the hole. After several days of testing drill head configurations, another 6 filter runs were completed. Fine slush is suspected to be generated while traveling with our (compared to last year) longer drill at depths with steep changes in inclination. Drilling status: 1263.75 m to 1360.73 m for a total of 96.98m. Drill fluid used, approx. 18.6 L/m estimated. During the coming days an optimized stable production using step cutters, a steeper cutting pitch and having reduced chips loss is expected to be found. Furthermore, as production seems to be hindered due to necessary filtering runs, a filter team has been formed to filter the hole in between drilling operations.

Weather: Sunny most of the weekend. Temperature -17 °C to -8 °C. Wind turning from W to N during Saturday, and then veering back to W and finally to S during Sunday. Wind speed between 3 kt and 12 kt, strongest from N.

FL, Bo Vinther

Left: Saturday chefs Masashi, Rigen, Ikumi and Sumito. Right: Close-up of the excellent Japanese Saturday dinner.