Great progress, a change of rock type

Last night and today, the drillers have really gone a long way.  We got a huge delivery of core this morning, and processed it to a depth of 335 ft.  Up at the drill site, they are at least 50 feet deeper than that at the time of this blog post.  Below is a picture of an interesting transition that we saw while processing the rocks today:

Remember in yesterday's update that all we were seeing was loose cinder?  Well we saw lots more of that...until this contact.  Note that the oxidized cinder on the left holds together in a coherent manner, which was surprising on its own.  In addition, the contact between cinder and nonvesicular rock beneath it is extremely sharp, a change so sudden that you could hardly get two more physically different rock types next to each other in such a setting.  We will have to carefully consider the meaning of this contact when logging both rock units later.  

Drilling with mud is working well

Since yesterday's update the drilling has advanced downward significantly; this afternoon we reached a depth of over 250 ft.  Part of the reason drilling has gone so quickly is because we are advancing downward exclusively through cinder.  The drilling runs have produced no consolidated cylinders of core, only small collections of cinder measuring much less than the downward advance of the drill bit.  We believe what is happening is that we are doing some cutting, but mostly pushing our way down through a cinder cone.  Although it would be nice to sample more solid rock, the cinder isn't caving into the hole and we're making good progress.

The drillers feel that making the switch to drilling mud instead of using foam has helped stabilize the hole as well.  Above, you can see the crew mixing up a batch of drilling mud (as well as another basin and a water tank for mixing even more).  Although this mud is a little more expensive to use in a place like PTA where the cost of water is high, the additional expense is worth it if it helps keep the sidewalls from caving in around the drill pipe.       

A drilling breakthrough

Apologies for the delay in posting this update, I have been waiting for some good news to share on the drilling front. 

Over the past week or so, the drillers have filled the hole with cement and then drilled through that cement in an attempt to stabilize the loose upper portion of the hole.  In addition, casing was set at a depth of very solid rock, about 90 ft below the surface.  This casing was also cemented in place and will prevent any cave-in material along its length.  More cement was poured into the hole and allowed to harden, and then Master Driller Ron Fierbach went in with an unconventional setup to try and drill alongside the material stuck in the hole.  He drilled without the stiff core barrel, instead using only a drill bit attached to regular drill pipe.  This enabled him to deviate slightly from the old hole, and once the bit started to cut some rock instead of only cement, it was drawn into the rock and away from the cement.  Below is a picture that from left to right shows progressively deeper core samples drilled by this method. 

The far left core shows a combination of rock and cement, but the amount of cement decreases in the downward direction.  The second core piece shows significantly less cement at its bottom.  The third piece shows even less cement and the curved, cut face of the sidewall of the old hole.  The last piece shows some of this curvature as well, but advances down to a complete cylinder composed entirely of newly drilled rock.  The significance of this image is that it indicates we are now out of the old hole and drilling alongside it.  Although we aren't in the clear yet, this is a big step in the right direction.  The next question is whether we can drill past 130 ft, where the collapse occurred before.  This time most of the hole is cased, so hopefully encountering a lava tube void space won't cause so many troubles.  We don't know how much more loose material we may have to drill through, but hopefully we'll be through it soon.   

Logging and more difficulties drilling

Today we had a lot of rock core to process.  It took all morning to wash, dry, mark and box the rocks to a depth of 128 feet.  The afternoon was spent photographing and logging the rocks, and trying to decipher their complex geologic relationships.  Below is a photo of most of the boxes lined up and waiting for us to interpret them.

Drilling Update: Poor drilling conditions continued today, and we encountered an open void space that was larger than any we had passed through before (probably a lava tube).  As a result, circulation of foam was lost into the opening and loose material collapsed in around the bottom section of pipe, pulling it completely off the rest of the drill string.  In order to continue drilling, we first have to clear the hole down to the broken-off piece of pipe with a rotary bit, and then fish out the lost pipe.  This will be a challenging endeavor, and will take at least a few days because of the need to ship in more rotary bits.  Please wish the drill crew luck, they have a lot of tricky work ahead of them in order to continue to advance this borehole. 

Looking for a few good lavas

Over the last 24 hours, drilling has progressed slowly because of the unconsolidated nature of most of the rock we've been drilling through.  This does not come as a complete surprise, since the PTA area of the saddle where the drill rig is located can be viewed as a basin that collects erosional products from Mauna Kea.  In addition, the post-shield stage cones of this volcano (see below for an example) have erupted and deposited loose cinder that we have to drill through as well.  The best drilling has been through solid lava rock, but so far we haven't encountered much of it.

Last night it was necessary to trip out and change the bit, because unconsolidated material eats away at drill bits much faster than hard rock does.  As of about 3:00 pm today, we have progressed to 98 feet below the surface.  The goal is to keep drilling slowly through this section until we encounter solid rock in which to set casing.  At that point, we will attempt to widen the hole with a rotary bit and set casing on the solid rock formation at the bottom.  The casing will extend to the surface and keep loose material from caving into the top of the hole as we continue to drill downward.  Stay tuned for further updates on our attempts to stabilize the hole for better drilling penetration and recovery.     

Drilling with foam

Today we began our regular drilling schedule.  In an attempt to limit our water use in the upper, dry portion of the hole, we are using foam as a lubricant.  It will take some time to determine the proper foam/water mix for the drilling conditions, but so far the foam is doing its job well.

    By the end of the day shift, drilling had progressed to a depth of 60 ft.  At 100 ft we will stop and widen the hole with a rotary bit, then set and cement casing to that depth.  This casing will help prevent the loose rock near the surface from caving into the drillhole. 

Our first core run of the project!

Drilling began today and we took it slowly so that our new drill hands could get some training in what working on a drill rig is like.  All the drillers and drill hands, as well as the Principal Investigator and Rock & Data Manager were present at the drill site for the first drilling day of the project.  Pictured below is the first recovered run of core.  Preliminary examination of this run has revealed a xenolith-rich unit from Mauna Kea's alkalic post-shield stage.   

Our 24-hour-a-day, 7-day-a-week drilling schedule begins tomorrow.  After the core is recovered from drilling at PTA, it will be transported down to UH Hilo where the core processing crew will be washing, drying, marking, photographing, and logging the rocks.  Soon in addition to these blog updates, lots of photos and data will be added to the other pages of this web site.