The morning sun now hits the drillsite at 08:20, significantly earlier than when we started building the drill pad here in August! In another few hours, after the drillstring has been inserted, we expect to recover our first cuttings from the deep drilling phase, drilling an 8 1/2 inch hole.
The drill site was quiet first thing this morning, but we will see action very soon. All the teams are ready to do their respective jobs, and presently feeling pretty proud of the facilities we've established.
The downhole geophysical data collected a few days ago are being analysed, and the deep drilling rig set up for the basement drilling. Everyone is really keen and super excited!
This morning we have excavated for, and installed a cellar around the wellhead. We expect to move the deep-drilling rig over the hole late today, trip in pipe early tomorrow and be drilling again by late morning. Exciting times! The team are also considering the results of the wireline run into uncased rock for about 10 m beneath the 10 inch casing.
Today we drilled a short way (less than 10m) out of the bottom of the 10 inch casing into the basement. The Washington's rig was moved off the borehole late afternoon and the Montpellier team are now running wireline tools. We are excited about the next stages, which include mobilising the deep-drilling rig, and very grateful to the team from Washington's for the excellent work they've done for us so far.
7am shift change coincided with the call of 'garnets in the cuttings', a criteria Tim Little and others had set as a final requirement to make the call that we are drilling basement rather than gravels. We are fairly certain we encountered the Quaternary-basement interface at 240m. 10 inch casing has been advanced to 264m, and we are drilling a 9 7/8 inch hole 12 m below casing this that we hope to wireline log early tomorrow morning. Then we'll have a few days' downtime as we change rigs.
A slow day onsite for the Science Team. The drillers advanced 10 inch casing to 236.6m and recommenced drilling with dual rotary just before the evening shift change. This seems to be progressing well. We are looking forward to encountering basement.
While the drillers have been running in 10 inch casing (now at just over 100m), the science team have been preparing their instruments and undertaking 'site improvements'. We're looking forward to continuing to drill around lunchtime tomorrow. Nice weather and a delicious BBQ dinner tonight has left everyone feeling positive about the next stages of the project.
This morning was pretty exciting as our borehole started to yield artesian flow at a rate of 5l/s and up to 42 deg C. We considered starting up a business as the 'Whataroa Thermal Baths' but instead decided to change the mud weight to counteract the fluid pressure. As of this evening we have advanced 12 inch casing to 236.6m and are now running 10 inch casing inside this.
We enjoyed showing our onsite facilities to more than 30 visitors from the ICDP Active Fault Zone drilling workshop yesterday, but think they didn't enjoy the wind and rain very much! The downhole geophysicists' logging container has also arrived and they have started testing their equipment, so far successfully. Tonight, in dry weather under a nearly full moon, we continue to advance 12 inch casing and generate cuttings of clasts in Quaternary sediments. Depth 224m at the end of the day.
Welding of the 12 inch casing string was completed this morning and we are now drilling with a dual-rotary system that advances casing at the same time as the hole is drilled. There was excitement late afternoon when the cuttings showed that we were drilling in schist, suggesting that we had reached bedrock. However, after several hours of slow going and at a depth of about 202m, the drillers confirmed that we had been drilling through a schist boulder and that we have not yet reached basement. Drilling will continue overnight and we hope to encounter bedrock soon. With the arrival tomorrow of the wireline logging container we will have the science facilities largely completed. The weather was fine most of the day but another strong storm is forecast overnight: it?s good to have our equipment stowed away and ready for action in the days to come.
Yesterday we reached the base of silts at a depth of 194m and encountered diamictite. The rate of penetration decreased significantly and a decision was made to run 12 inch casing to that depth. This morning, the drillers started to construct and install the casing string and this is expected to be completed by late tomorrow (7 October). We will then advance the casing to greater depth using a dual-rotary drilling method until bedrock is reached, or the casing cannot be advanced further. After crisp but cold conditions late last week, the weather deteriorated yesterday, and by 10 pm torrential rain and strong winds made conditions on site very challenging. The wind was strong enough to move one of the shipping containers but the drillers continued working through the night. Meanwhile, setup of on-site facilities is progressing steadily despite the adverse weather. On Sunday, we put up a canopy between the science containers to provide a sheltered work area, and our computer systems and the DMT Corescan3 and fixed camera photography have been installed. The canopy was strong enough to survive the storm. Today we will focus on establishing the thin sectioning facilities. Many of the science team have now arrived in Whataroa, but several people have departed temporarily for the ICDP training course being run this week in Franz Josef Glacier. While they are away, we will continue setting up equipment and preparing for open-hole drilling later in the week.
