Spare parts for the drilling system have not yet arrived in Potrok City. Some scientists used this extra time for a trip to Laguna Chaltén and Laguna Azul to remove monitoring devices including a mooring with thermistors, pressure sensors and sediment traps.
While another heavy storm is preventing us from work on the lake, scientists are discovering the environment surrounding the camp. They found ancient rock paintings (rock art or pinturas rupestres) at a nearby basalt cliff crafted by the extinct native Indian tribe of Patagonia, the Tehuelches.
Today we continued with another hole at site 2. First we drilled down to 50 m sediment depth without taking samples and then recovered 21 m of cores without problems before the wind picked up and gusts hit the platform. Unexpectedly, this caused a drifting of the platform and in consequence the drill pipe broke. We lost a tool and some drill pipe.
A heavy storm with Beaufort 9 and gusts up to 110 km/h also hits the PASADO field camp Potrok City. For security reasons all drilling operations on the lake had to stop for the entire weekend.
89 m of sediment were recovered without any problems at the new site 2A. After this very successful day of drilling – the nightshift alone drilled a record core length of 72 m! – the drill pipe was completely removed from the hole and casing was pulled up ca. 10 m to make sure that the upcoming storm can do no harm to the drilling platform. We really look forward to continue at this site after the storm passed by.
After having reconditioned the platform yesterday it was towed to the second drill site today. There it was securely anchored and the casing was installed down to 90 m.
Heavy wind conditions did allow working on the lake only in the morning. Drillers used this time to analyse the damage of the storm. Scientists caught up with laboratory-based activities.
Very early in the morning problems with sandy layers in the sediment occurred and the hydraulic system of the drillrig failed to work. Thus the last shot was recovered only hours later at twilight when the hydraulic problem was fixed. Hole D had to be abandoned at 98 m sediment depth. Smear slide analyses in the laboratory demonstrated that we were back to diatomaceous lake mud! It was then decided to continue with downhole logging. Everything was set up when the wind picked up with force and work had to be stopped for security reasons. The strong westerly winds with gusts over 100 km/h caused the drill pipe to break and the anchors to fail. The platform drifted towards the eastern shore line. 300 m off the shore anchors started to hold again and the drifting ended. However, one anchor line broke and we lost this anchor. While the lake water was virtually boiling, two drillers and two scientists were trapped on the platform for the entire day with water splashing over the platform. The catamaran was not able to pick them up until dawn.
The application of drill mud did allow passing the sandy sections without major difficulties. See the video -Night shift at work - coring at Laguna Potrok Aike: http://www.youtube.com/watch?v=HZXyDbJcsmM
After logistical problems were sorted out on the days before, drill mud was now available to overcome the problematic sandy sections. Before application the hole was cleaned with the Alien tool. Due to unknown reasons the drill bit was lost in the hole. Thus the C-hole had to be abandoned at a final depth of 63 m.
Drilling at the first site continued. From a depth of ca. 60 m downwards sand and rarely gravel was recovered. Very sandy parts of the record finally caused us to terminate hole A at a final depth of 81 m. The B-hole was started in the evening of the same day.
After introducing platform and drillrig to the scientists, the DOSECC crew started with drilling operations. After four weeks of delay the first shot was on deck soon and celebrated by everybody. Drilling in shifts began.
Early in the morning the platform was towed to the first drilling site, casing was set and the drill pipe was lowered close to the depth of the first shot.
