You are currently viewing July 7: Reaching 71m in the casing and first Basler shuttle to SFJ.
Julien mounting one section of Kovacs augers after another, to a total length of 15m. As these are too long for our tower, the full length has to be assembled down hole, with all of the drill team supporting from above by lowering the individual pieces on climbing ropes.
Julien mounting one section of Kovacs augers after another, to a total length of 15m. As these are too long for our tower, the full length has to be assembled down hole, with all of the drill team supporting from above by lowering the individual pieces on climbing ropes.

July 7: Reaching 71m in the casing and first Basler shuttle to SFJ.

Driller’s report: ‘Today was an epic day! We made more progress down hole than any other day before. In a final attempt to gather information from beyond the 56m blockage, we grinded down the housing of the borehole camera to fit it into the Kovacs augers, instead of a cutter. This was a perfect fit. The camera was now in line with the augers and we could attempt to enter the hole we drilled earlier in the day. We added 15m of augers to the drill, giving it a total length of almost 20m.

With this setup we managed to get the camera beyond the 56m blockage, beyond the 80cm blockage in 59m depth, beyond two more sets of broken casing connections, and into an at least 75cm thick blockage of fiberglass and snow, at a final depth of 71.35m. The blockages at around 59m and 71m consist of larger fiberglass pieces and loose snow, which can be penetrated by gently smashing the camera into it.

As the motor section of our drill has a larger diameter than the camera and augers, it cannot pass the blockage at 56m depth. Thus, using all the 15m of extension rods for the auger, we will most likely not be able to penetrate further down the hole this season. Tomorrow we plan to deploy the logger, to further investigate the borehole casing kink at around 15m depth.’

 

While the ICELINK people have been drilling ice cores in various places, Nora has been busy logging borehole temperatures. The ice stores a record of past temperatures and by comparing todays borehole temperature with similar measurements made back in the 1980’ties Nora can determine if the ice sheet has warmed up since then. And guess what, it has! There are caveats, however, because when the drill is cutting the ice core free, it actually heats up the surrounding ice a little, and so the temperature profile should better be obtained some time after the drilling. And then there is the seasonal temperature variation that enters the snow from the surface, but that is damped to the average annual temperature at around 10 m depth.

 

Today, the Basler left for Kanger with drill equipment and all of the ice cores that were drilled over the last week. The shallow drill was left behind so that a few more cores can be drilled in the coming days before the drill and ICELINK group will go south and drill another core close to the cold-war Dye-3 radar station in the southern part of the ice sheet.

 

What we did this Tuesday:

 

  1. Using innovative solutions, the borehole camera made it to 71m depth
  2. The Polar 6 Basler left for SFJ with ice and cargo
  3. Anton collected all geophones placed in the surroundings
  4. The mechanics garage was documented
  5. The Mega trench was deepened to 6+ m and the sampling mania goes on
  6. More stuff was moved in the main storage trench
  7. A nice floor was made in carpenter’s garage

 

Weather: Not much sun and no contrast today. Wind 6-15 kt from N. Temp -14C to -5C, the warmest temperature at GRIP this year, so far.

FL, Anders Svensson

Things are getting desperate! In a final attempt to get more footage from down hole, Chantal and Steff are grinding down the casing of our borehole camera, to fit it into the cutter slot of the Kovacs auger.
The perfect fit of our camera at the front of the auger. The setup made it impossible to rotate the drill, but gentle tickles convinced the camera to its final depth of 71.35m.
The entire drill team missing out on dinner to get the camera further down into the bore hole. While this may look like a construction site, where only one person is working, each of us had our tasks in the operation to make this camera descend a success.
Sune and Shari serving Flæskesteg med meget sprød svær.
Nora about the borehole temperature profiles: Clausen et al. (1988) drilled ice cores and measured borehole temperatures 40 years ago at several locations close by to identify the optimal drilling site for the deep ice core. We returned to Site E, thereby extending the ice core record and again measuring the borehole temperatures. This temperature profile shows how the annual temperature cycle is slowly diffusing and advecting into the ice sheet. The overall temperatures are higher than those measured 40 years ago, which is expected due to the recent anthropogenic warming of the Greenland Ice Sheet. How much warmer the ice is today remains uncertain, however, as the borehole temperatures appear warmer right after drilling (blue dashed line) compared to 1.5 days later (orange line) - except at the lowest depth, where the drill motor probably didn't touch the ice. It is possible that our new borehole, as well as the one from 1985, were not in thermal equilibrium when the final measurements were taken. We will begin continuous temperature measurements in a new borehole close to the camp in the coming days, to better quantify when thermal equilibrium is reached in a borehole after drilling and to learn more about the ongoing warming of the Greenland Ice Sheet.