After disassembly of the barge started on Monday, it finished at noon today. The entire DOSECC equipment is now loaded on trucks and on the way to Greece, the refer is fully loaded with sediment cores on the way to Cologne. The SCOPSCO drilling is finished. Therefore, we will use the next couple of days to make a seismic pre-site survey at neighboring Lake Prespa...you never know...
DEEP site: - total drill depth 2088.71 m - total recovery 1526.06 m - deepest drill depth 568.92 m blf - composite field recovery 544.88 m / 568.92 m (95.77 %) Cerava site: - total drill depth 175.71 m - total recovery 172.20 m - deepest drill depth 90.48 m blf - composite field recovery 87.86 m / 90.48 m (97.10 %) Gradiste site: - total drill depth 327.35 m - total recovery 224.46 m blf - deepest drill depth 123.41 m blf - composite field recovery 114.07 m / 123.41 m (92,43 %) Pestani site: - total drill depth 194.50 m - total recovery 177.90 m blf - deepest drill depth 194.50 m blf - composite field recovery 177.90 m / 194.50 m (91.45 %) total drill meters : 2786.27 m total recovered meters 2100.62 m (75.39 %)
The anchors of the barge were lifted in the early morning hours. Calm conditions promoted towing of the barge to the shore with the HBI boat. At 3 PM, the barge reached the shore and disassembly started. The drrilling operation comes to an end.
The hole at Pestani site was drilled down to ca 194 m sediment depth and finished with the end of the nightshift. the sediments were clay and silt, but we wanted to get the borehole loggers in, before we need to disassemble the barge. Over the day, the borehole logging took place.
The drilling operations continue. We chartered one of the tourist boats on the lake to tow the barge from Gradiste site to the last site in front of the eastern shore. As we still have some technical problems with two of the anchoring winches, it took quite a while to get two of the four anchors free after the storm. In the late afternoon hours, however, the barge was positioned at the new site, and drilling started with the nightshift. Everybody is happy that drilling is ongoing again and that there is still a good chance to get at least one core from this site with a water depth of 260 m and a target depth of ca 150 m. Drilling will be finished latest on Sunday (June 2nd), when the barge will be towed to the shore again for disassembly.
A day to recover and to check a bit more in detail the damages from the day before. The HBI boat is undergoing first repairments, and also the dock in front of the hotel needs some face lifting...
After another day (25.05) of waiting for calmer weather, we experienced one of the worst day here. Engine problems at the HBI boat, high winds and waves caused that the boat smashed for 1-2 hours on the dock in front of the hotel. Everybody was helping to keep the boat from the dock as good as possible. The dock got distinctly damaged, the boat also had some damage, but at the end of the day, nobody was injured, the boat (and also the shuttle boat) was still floating. A tourist boat managed to tow the HBI boat into the hangar of the institute. A long and hard day for everybody.
After the nightshift has duplicated the sequence between ca 80 and 116 m at Gradiste and this site is finished now, we started with the preparation to tow the barge to a new site in front of Pestani. However,more wind came up during the day and there were too high waves to re-position of the barge. The next try will be made tomorrow.
The borehole loggers finished logging the hole in the early morning hours. However, strong winds at 7AM did not allow us to pick up the nightshift and the borehole loggers from the barge until around noon. In the afternoon, the weather stabilized a bit and the dayshift started with a new hole at Gradiste site and reaming down to about 80 m in order to duplicate the sequence between ca 80 and 115 m sediment depth.
After the nightshift penetrated a gravelly horizon at 82 m depth, shallow water facies, rich in carbonates and interspersed by peat layers, characterized the sediments down to ca. 112 m sediment depth. Below this depth, darker, fine grained sediments continued. Coring was stopped at a bit more than 120 m due to wireline problems and because we do not have seismic data from the horizons below, which makes the scientific interpretation of these lowermost sediments difficult. The borehole loggers started logging the Gradiste site, hole 3C, in the late afternoon.
The nightshift hit into shallow water facies and gravel at around 82 m sediment depth. Due to a technical problem, the hole had to be given up and a new hole was started at the Gradiste site. Over the day, the Gradiste site was duplicated.
Coring at Gradiste goes on. At the end of the day, the nightshift was at ca 81 m below lake floor and recovered mostly clay, but also some interspersed sand layers.
The Cerava site was finished in the early morning hours. Lifting the anchors, towing the barge to the Gradiste site and setting the anchors was supported by calm weather and took 8 hours in total. The barge is now just in front of the hotel, which makes the shuttle for the shifts very short.
In ca 87 m depth at the Cerava hole 2B, we found a conglomerate of gravel, sand and lots of snail and mussel fossils, underlain by not lithified sand a gravel. There was no further penetration below ca. 90 m, so we closed drilling at Cerava site and started with borehole logging.
Good progress at the Cerava site in the uppermost ca. 70 m. As we run out of liners, we had to order more liners from UK, and they arrived just in time. At the end of the day, massive sand below 80 m avoided however further penetration, so the nightshift started the second hole at Cerava site. The sand likely originates from paleodeltas and clinoforms visible in the seismic data.
The borehole loggers finished the logging of hole 1F at the DEEP site in the evening hours of the 13.05.13. The nightshift tripped out all the pipes and prepared the barge for towing. The dayshift on 14.05.13 started to pulling anchors. It took quite a while until all anchors became free, but finally, around midday, the weather was with us, calm conditions established, and all anchors were lifted. Towing the barge from the DEEP site in the center of the lake to the CERAVA site in the southeastern part of the lake took about 5 hours. The first anchor dropped at CERAVA site at 8:30 PM, the fourth anchor was set around 2-3 hours later. At midnight, the barge was ca. 180 m off the coring location, but pulling on the anchor winches should correct this. This was a long day, but everybody is happy that the re-positioning was successful and that there is a new landscape after having seen 5 weeks the surrounding of DEEP site.
Hole 1F was finished in the evening hours at a little bit more than 550 sediment depth. After the nightshift (11/12 May) had a very good recovery and a good progress, the dayshift had to fight again with the wireline. The last run of the dayshift and the first run of the nightshift in the evening hours revealed sand and gravel in the core catcher and poor recovery. So we decided that it is now time for borehole logging and to finish the DEEP site tomorrow. The weather these days is a bit more unstable compared to end of April, we had some more technical issues in the last days, but overall everybody is happy and a bit tired from the last weeks, so a day of recovery is very welcome.
The Macedonian harbour master inspected the platform today. Drilling progress is slow and needs many bags of bentonite. After the night shift arrived on the platform the hydraulic system of the drill rig failed but could be repaired after 5 hours. At 11 pm drilling continued.
We look back to a day full of challenges. Firstly, the starter of the HBI boat broke after the delivery of bentonite to the barge in the morning hours. While we brought the starter to a garage in the city of Ohrid, Jess punctuated his hand with a screwdriver on the barge. The medical examination in the hospital indicated that fortunately the movement of his fingers was hampered just by a hematoma. After repairing the starter we brought Jess and the starter back to the barge and the HBI boat but bad luck continued. Another break of the wireline caused the rods to get stuck. The HBI boat was repaired and left the barge at 11 PM. Eventually the rods got free at 2 AM in the morning.
Besides some thunderstorms forcing the drilling operations to be stopped for some time we are again in 450 m sediment depth. Bentonite is needed again that got delivered yesterday, just on time. The down-hole logging team arrived yesterday and is on standby.
We repositioned, took a surface sediment sequence (Hole 1E) and now started spot coring in Hole 1F in order to fill the last gaps down to 420 m. From this depth to the pebbles at the base of Hole 1D we will try to duplicate the sequence. A few thunderstorms delay the coring progress these days.
Coring was stopped at 568.92m sediment depth, after we went through coarse gravel and pebbles increasing in size and after four core bits gave up. As there was an overall increase in grain sizes between 420 and 568 mblf we do not assume that there is any chance to find fine grained lacustrine deposits below. It is more likely that we drilled into the initial fillings of the early stage of Lake Ohrid basin.
Weather conditions and drilling equipment is still on our side and we are going deeper. The Bentonite consumption increases from day to day, therefore we have to go out to the barge with the HBI boat 1-2 times a day.
The drilling progress slowed down because the stabilization of the hole gets more and more important. The core recovery is also very poor but we keep trying to get deeper.We are running out of bentonite soon which could be a problem as in Macedonia there are easter holidays.
Beside some slight changes in the personal staff of the night and day shift of the drilling crew, we can report that drilling goes on and on and we are approaching the sediment depth of Hole 1B and 1C.
A great day without any setbacks and more than 60 m filled liners. On the way back from the barge the surface temperature of Lake Ohrid was tested by natural skin thermometers, the swim season is declared open!
After fixing some smaller technical problems, operations at hole 1D are continuing. We hope to avoid a new break of the wireline by running it a little bit slower. So we made "only" 75 m of recovery during the last 24 hours, hence arrived at 240 m sediment depth in hole 1D now. Weather is still excellent and so we are confident to obtain a very good recovery for the DEEP site. As hole 1C had a total recovery of > 92%, we now have a total recovery (composite sequence) of 474 m for the 480 m long sediment sequence at the DEEP site. We hope that hole 1D will allow us to look even deeper into the sediment fill of Lake Ohrid.
Although some technical problems are still delaying the coring progress, the atmosphere on the barge and onshore is very good due to sunny days and an amazing landscape...
In the early morning hours a V-belt broke causing the drillling operations to be stopped. It took the entire day before the night shift could continue coring.
While Bernd is struggling to get the cores of Hole 1B and 1C into Hungary, drilling operations and logging of the cores in the lab at Hole 1D are going on and we are at a sediment depth of 70 m again. We are nevertheless optimistic that the first load of cores will arrive in Cologne on Monday. Today the 1000 m marker of total depth drilled was reached. Although due to ongoing problems with the wireline coring had to be slowed down. Speaking of weather conditions here at Ohrid, today was the first day where we considered to go swimming in the lake. Unfortunately only the air temperature is high enough to do so.
Drilling at Hole 1D started today. Everything back to normal the refer is filling up again. The diatom experts arrived at Ohrid in order to take a look at the smear slides.
After one day off, more than 900 m of sediments are now on the way to Cologne. This gives us more space in the refer here. The plan is now to move the barge by another 20-30 m to the north at the DEEP site and to get a third long sediment sequence, as long and complete as possible.
During the night, the borehole logging team finished logging hole 1C. Though it was a tough time, with short nights, the team was very happy that the hole was stable and logging was very successful. Tuesday is one day off for the entire team. The pipes and tools are out of the water and are checked for starting hole 1D at the DEEP site tomorrow morning.
Though the wireline was broken at the last run during the nightshift, the team managed to fish the tool and get the last core of hole 1C on deck. So hole 1C is closed now at 479.59 m sediment depth. Overall, ca 960 m (2 x 480 m) of sediment were drilled in a total of 17 days. With the dayshift, the borehole logging team went on deck of the barge and started with their preparations for logging. Now, it is time to do some maintenance on the barge and the equipment, to recover a little bit for the entire team, and to celebrate a bit the immense success obtained during the last three weeks.
After another 2 days of calm weather, there are several exiting numbers to present. At midnight, the night shift was almost 380 m below lake floor. In the last 24 hours we have drilled 123.74m with almost 100% recovery! The entire team here is doing an excellent job, and we figured out that we are running into a storage and cooling problem here. So we are now planning to send a first set of cores already to Cologne next week to get space here for the next weeks. After hole 1C will be finished, probably at a similar depth as hole 1B (ca 480 m), the borehole logging shall take place. Borehole loggers will come in to day to be on standby for a potential start during the weekend.
Another sunny day on the barge. Some minor technical problems occurred on the barge and with the shuttle boat during the last days. Most of them were solved quickly so the core progress was not really stopped and after the end of the day shift, we were down at 170 m in the second hole (1C). We started to realise that if we continue this way, we are running into serious problems with core storage and cooling capacity, but we also will solve this rather nice problem somehow...
After hole 1B was finished, the platform was moved ca 20 m to the north and we started with hole 1C in order to get the overlaps and the missing parts. After one day of drilling and some smaller technical and weather (wind) setbacks, we are now at ca 120 m again and optimistic to continue during the night shift. The borehole logger team will try to arrange to be here again on the weekend, as there is a good chance that hole 1C will be logged pretty soon, if the weather allows.
In the early morning of the day, we decided to close hole 1 B at a depth of about 480 m, since the sediments became very coarse for more than 10 m thickness and apparently are of glacio fluvial rather than lacustrine origin. In order to avoid a collapse of the hole and potential loss of coring equipment, we now will start duplicating the hole and fill the gaps to this depth, before we may try to go deeper. After moving the platform about 20 m aside, drilling started again at the sediment surface using the hydraulic piston corer.
After the rods got free again the coring progress is good again and we are at a sediment depth of about 460 m that were drilled in less than 2 weeks. We are very lucky with the weather so far. Cores are more variable in color and sediments contain coarser material. Bentonite, now, is the best friend of the drilling team right now which also keeps Captain Zoran quite busy because he is in charge for the supply to the barge.
At a sediment depth of about 420 m we had shell fragments in one core indicating shallow water conditions. A little bit unexpected in that depth already. In addition the rods got stuck and it took about 3 hours to get them free again. Meanwhile onshore, the MSCL logging team tries to catch up with the high amount on sediments in tubes. This is only possible by using more than 3 computers at once.
the hole was more than 320 m deep and the core recovery was good again. Calm weather conditions these days really support the coring progress. Measurements in the lab are also advancing and the number of wiggles decorating the walls of the lab increases distinctly.
Preparations for the down-hole logging were made although we all hope that drilling will continue to greater depth. We are looking forward to warmer temperatures at Lake Ohrid like we are used to from the seismic surveys because especially for the night shift on the barge it would make work much easier.
The first core on deck at 0.01 AM was dedicated to Ascelina Hasberg as a birthday present from Lake Ohrid. Unfortunately, due to increasing wind the drilling operation had to be stopped in the early morning hours. Over the day the conditions became even worse and the drill rig was taken down. Later in the day slightly decreasing winds allowed a setting up of the rig again in order to keep the drill string unstuck.
