Drilling started at Betasso today. We reached a depth of 48 feet. We had no recovery in top 8 ft (but have bags of material from 2 ft increments), then segments that are highly fragmented, barely held together, for about another 10 ft. The top 20 ft is therefore cased to prevent collapse, and beyond that it's been clean sailing. We're seeing fractures, some with oxidized stains, and some filled fractures (silica?), maybe some faults.
We reached 148 feet today (a fractured altered section) and ran into some trouble. The drill bit was destroyed in the last few inches. After minimal progress, we blew a gasket and an air hose. Drilling was stopped as we had to wait for new parts from Denver.
After a rough couple of days we are getting back on track. We noticed dramatic differences between the last core recovered at 148 ft, and where we picked up 3-5 ft below (see pic 100_0594 attached). The recovered core is significantly more fractured and weathered as we continue down in comparison to the mostly intact core we have recovered at shallower depths. The last 5 ft run of core down to approximately 173 ft. we recovered had significant clay content and the rock pretty much fell apart.
We drilled through rotten rock today for most of the day and were unable to recover any core for 70 feet. We finally hit competent rock and recovering core again at about 230 feet.
Today is another slow drilling day at Betasso. We recovered about ten feet of solid core today and reached a total depth of 260 feet. We have been alternating between the air hammer and the diamond drill bit due to rotten rock falling back into the borehole. We still haven't hit the water table.
Today we almost drilled down to 400 feet.
Really cool pegmatite at the bottom of the hole! We lost circulation of drilling fluid again at 406 ft, and had to call it due to amount of time it takes to remove core from this depth, and the borehole taking longer than anticipated. Kamini Singha (Colorado School of Mines) ran downhole geophysics on the coldest days of the drilling project! She ran an optical televiewer, calipers, and gamma.
Drilling completed! We reached a depth of 124m. We encountered lots of hydrothermally altered granodiorite on the way down, which meant low core recovery below 45 m depth. The static water level at the end of drilling was 83 m below the surface. Core at the bottom of the hole ended on a pegmatite. Downhole geophysics completed today. Casing is scheduled for Feb 1.