Thursday, January 20, 2011

Drilling into New Zealand's Alpine Fault

The Deep Fault Drilling Project is now happening with the first steps at our first drill site underway. We have chosen a site beside Gaunt Creek, near to Whataroa on New Zealand's West Coast. Next to us the Alpine Fault is actually visible in cross section in a cliff beside the creek

For an overview and brief introduction to this project see Julian's Blog or check out the video below.

After several days of road improvements to access our drill site, Jimmy Arnold’s efforts were put to the test yesterday with the arrival of the trucks. The first truck weighed 42 tonnes and had difficulty getting round a few corners, but the road performed well and everything got to the drill site before lunch.

Three large trucks, at least half a dozen smaller vehicles, and a digger established our site. By
the time we stopped for dinner we had already hammered down 24 m of steel casing using a
Concentrix rotary air hammer system operated by John Butt.

Despite not expecting to start sampling for a few more days, we jumped into action and logged
cuttings and drilling progress. At the base of 9 m of bouldery gravel we hit water-charged sand and then passed into cuttings of homogeneous mylonite with abundant clay. The easy penetration and high saturation of water and clay indicated that, although we had reached the target of basement rock, it was unlikely to core easily or leave a stable borehole wall. We continued to knock down casing. Conditions improved below 19 m depth, with much less water and a moderate but stable drilling rate.

This morning we added one additional 6 m casing. From 20-30 m depth we had observed a stable drilling penetration rate through relatively dry (impermeable) fractured rock and there was a consensus between myself, Virginia Toy (Otago University), and the drillers John Butt (Butt drilling), Ken Mears (Westmere Drilling) and Brent Herrick (Horizon Drilling) that we now had a stable base to start coring operations from.

Here is the video that outlines the purpose of the project

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