Drilling is making steady progress, pulling up good rock core broken only by a small number of fractures in general. Our science crew loves that, because we can clearly see features in the core like the xenoliths shown below. These xenoliths contain mostly plagioclase feldspar and olivine, common minerals in Hawai‘i rocks, but these are larger mineral grains clustered together into a small rock of their own and found in a dike. This means that the olivine and plagioclase crystallized in a magma chamber and were carried upward in the dike as it fed a surface eruption. The xenolith never reached the surface, but instead cooled within the dike magma within the volcano. Our drilling has allowed us to see interesting features in the rocks like this. By the end of the day today, we processed rock down to a depth of 2707 ft.
Mahalo to Pūlama Lāna‘i for coming out to the drill site and digging us a sump yesterday (pictured below), this will allow our drill cuttings to settle out so we can re-circulate clean mud back down the hole. Drilling has been productive the last couple days, at the end of the day today we had processed core down to 2597 feet below the surface. We’re seeing a mix of lava flows and intrusions (dikes), with occasional olivine-rich flows being the most altered and friable rock type.
Last night the night crew (see photo below) used a rotary bit to drill through an interval of ~30 feet or so that was difficult for our coring bit. Then they cleaned the hole the rest of the night, in order to remove rock cuttings that had accumulated at the bottom of the hole. It appears our cement injection worked as intended, sealing off the sidewalls of the hole, and we were back to coring this morning. We’ve realized our mud isn’t viscous enough to carry all these cuttings all the way to the surface, because its pH is too acidic. We’ll be getting some soda ash to mix into our mud on Wednesday, and the right mixture of that with our drilling mud should eliminate the problem of cuttings accumulating at the bottom of the hole.
Yesterday the drill crew tried to stabilize the lower reaches of our borehole. A large amount of loose, sand-sized rock particles (probably a mix of drill cuttings and bits of rock falling in from weak formation units) have collected at the bottom of the hole and we need to circulate them out and block more from coming in. This sand grabs at the drill bit and pipe, and won’t let us progress downward with our drilling until we block it off. Our current strategy is to push cement down into the hole and into crevices on the side, so that when the cement hardens it will block the influx of the rock particles. Then we can simply drill out the center of the cemented region, and the hole should be much more stable. Our first addition of cement yesterday didn’t have much effect, but we’re going to try to put in another batch or two over the next few days. If that strategy doesn’t work, we may have to ship in more of the casing that we put in the upper portion of the well and try to seal off the ~800 feet we’ve drilled with that. I’ll post another update when we’ve made some progress on this issue; below is a photo of one small step of the cement job.
Last night the night crew had to trip out all the pipe to remove a stuck core barrel, and then trip it all back in before they could continue drilling. After that, the day crew got a few runs of beautiful core before a highly fractured one started causing the same problem they had last night, accumulation of cuttings in our drilling mud. We’re working on a solution to this problem, and hope to rectify it tomorrow. As of the end of the day today, we’ve processed rock core to a depth of 2294 ft.
Today we finally saw our first clear intrusion in the rock core, in fact we saw multiple intrusions. These intrusions are dikes that fed magma to surface eruptions in the distant past, and the magma that cooled into solid rock at depth and never reached the surface is what we’re able to sample by drilling now. Encountering dikes by drilling at the rim of the Lāna‘i caldera was expected, the surprise was that we drilled about 600 feet before finding some! In the picture below, you can see a high-angle dike that intruded into the overlying rock in the far left column of the core box, and some of the features of the dike rock itself like vesicle banding and a slight coarsening of the groundmass (indicated by the gradation to lighter gray color) in the rest of the box. As of this evening, we’ve processed rock core to a depth of 2147 ft below the surface.
Drilling is proceeding steadily and producing some beautifully intact rock core. While I’ll give our drillers a lot of credit for that, the altered nature of the rock is also helping to cement what was once loose and fractured material back together into solid rock. Processing the core is going smoothly as well, today we processed to a depth of 2036 ft.
Drilling is progressing steadily, today we processed core to a depth of 1916 ft. We’ve been drilling in another breccia unit for a full day now, and it’s much thicker than the shallow one I posted about before. This unit probably was the result of a much larger landslide event. Everyone is curious how thick it will end up being, and what the rock will look like underneath.
Drilling progress remains steady, despite the condition of some of the rock we’re recovering. Oxidation, clay, zeolites, and the process of early serpentinization were all observed in the core today by the science team. Below is a photo of a new secondary mineral I don’t recall seeing before, with acicular habit growing inward from the walls of a large vesicle. We have currently processed core to a depth of 1800 ft.
After replacing the transmission on the rig and other servicing over the past couple days, we were back to drilling yesterday afternoon. We’ve made good progress since, and today the science crew processed core down to a depth of 1667 ft. below the surface (from a starting depth of 1480 ft. where we started deepening Well 10). Below is one of the more interesting units we saw today; a breccia that is probably a landslide deposit. Such deposits are common around the rim of the active Kīlauea volcano caldera today, and Well 10 is located at the southern rim of the Pālāwai basin on Lāna‘i – the modern region thought to represent the caldera of the long dormant Lāna‘i volcano.
Aloha, we’re all excited around here as the night shift produced the first ~35′ of rock core for the project. They had a rough time with some of the rig equipment though, so the day shift is currently doing maintenance on the drill rig. The core processing team examined and boxed up the core shown below, the rock looks like it all comes from a single thick pāhoehoe flow. There are few fractures, and the core is chemically altered with secondary minerals (probably zeolites) filling most of the small vesicles and lining the larger ones. The olivine is quite altered and seems to be larger and more abundant with depth in the unit, indicating it settled downward as the hot flow cooled.
The casing insertion and cementation is still a work in progress, so today I’ll talk a little bit about the science side of the project. My crew and I have our area set up and ready to go, off site and down the hill toward Manele Bay where we have shade, water, electricity, and storage space. Our latest creation is shown below, a 64 square foot drying table that can hold up to 24 core boxes. The sunny weather of Lāna‘i will be a great asset in drying out the core in the boxes before we stack them into storage.
Over the past couple weeks, the local crew members from Hawai‘i have been setting up the drill site with much-appreciated assistance from Pūlama Lāna‘i. All our shipping containers, vehicles, mixing and storage tanks, and other equipment including the drill rig itself are set up on site and ready to go. Two days ago, the rest of our drilling crew from our partner IDEA Drilling arrived, so everyone is here and ready to get to work. To start the project on the right foot, we had a blessing at the site led by Lāna‘i City’s own Pastor Saul Kahihikolo.
Today at the drill site, the crew inserted PWT (5″ inner diameter) casing into the existing ~1400′ Well 10 and cemented it in place at the bottom. The cement will be checked tomorrow, and if it’s cured solid then they will insert smaller PQ (3.375″ inner diameter) pipe as another layer of casing in the hole and also cement it in place. Finally, once all the casing is in place we can start coring with a HQ bit that produces 2.5″ diameter rock core samples.
Updates will be frequent from now on, stay tuned for more pictures and information!
Last week, Principal Investigator Dr. Nicole Lautze and a small team of graduate students and collaborators visited Lāna‘i in preparation for the upcoming drilling. They met with representatives of Pūlama Lāna‘i (the island’s land and resource management company) and worked out some of the preliminary details concerning housing and other facilities that will be made available to the project.
University of Hawaiʻi at Mānoa President David Lassner was on Lāna‘i and took the time to come and visit the Well 10 site that we hope to begin deepening within the next few weeks, showing his support for the project.
Mahalo to Pūlama Lāna‘i and President Lassner for your help and support! All of our gear is expected to be on the island sometime next week, and then we’ll begin preparing the site and hole for drilling. Check back here for more updates soon, which will become daily updates once drilling begins.
Last week, our European collaborators came back to finish the downhole geophysical surveys that could not be completed in February. Although only the first hole on the grounds of the PTA cantonment could be surveyed, the data acquired last week from these surveys is excellent and there were no major problems in getting it. After some processing of the data this summer, a paper using this data and corresponding rock sample petrophysical measurements in the lab will eventually be published. Additional papers are also in the works, including a general overview of the stratigraphy of both holes and a study of secondary minerals in the lower portion of the first hole where we found elevated temperatures. We hope to submit these papers for publication by the end of the year, and that they will spur further interest in researching the geology and hydrology of the two saddle boreholes.
The visit by a couple of our collaborators is complete, with mixed results. Above, Dr. John Millet and I are pleased with having completed sampling of the rock core from both of the saddle boreholes. John will return to Aberdeen, Scotland and conduct a variety of petrophysical measurements on these samples on behalf of VBPR.
As for the downhole geophysical logging, that didn’t go as smoothly. A multitude of drilling-related problems plagued us the entire time that the ICDP–GFZ group was here from Germany, and they were only able to conduct two surveys out of a planned dozen or more. Although this was disappointing, we finally overcome those problems yesterday and are hoping to schedule a return trip for this group in May.
Logging of the rocks was on hold while collaborators were in town, but now we’re back at it and we only have ~500′ left before we’re finished with our logging reports for both holes. At that time, I’ll be reviewing and finalizing everything for a while. In another month or so, all the box photos from both holes will be available online, as well as lithologic unit logs for both holes and the logging reports themselves.
Last week, we had a preliminary visit from some of the team that will be conducting downhole geophysical surveys in each of the two wells we’ve drilled in the saddle. We discussed some of the logistics of carrying out the surveys, as well as future sampling and research plans. Everyone is excited to conduct the surveys and collect samples for petrophysical analysis early next year. We’d like to thank everyone who visited for their commitment and enthusiasm! Check back soon for a group photo from this visit.
I also want to mention that we’ve been working steadily on the petrographic core logging reports, and we’ve now described the rock down to ~4000′ depth in great detail. Logging has been difficult due to alteration by hydrothermal circulation around this depth in the hole, but we’re definitely in the home stretch now. We expect to have the logging reports finished or nearly so by the time the downhole geophysical surveys take place (tentatively scheduled for February).
Yesterday was the last day of drilling for Hole 2 of the project. The end came upon us a little sooner than expected, but drilling conditions just became too treacherous to continue. Although sea level (~5400′) was our target depth, it was an arbitrary goal since this hole has been saturated with groundwater since ~1800′ anyway. The numerous confined aquifers we encountered during drilling more than proved that there are abundant high-elevation water resources beneath the western part of the Humu‘ula saddle. Stay tuned to this site for more updates as we log the Hole 2 rocks into early next year, and host collaborators who will conduct downhole geophysical surveys tentatively scheduled for February 2016.
Yesterday they had another solid day and night of drilling, recovering ~80′ for us to process today. Almost all of the rock recovered was pahoehoe, which is rare because this hole has been dominated by ‘a‘a flows. Still, there have been a few days like this where we drill through some extremely thick compound pahoehoe units made up of many individual flows. If drilling continues to go smoothly, we’ll process below the 5000′-mark tomorrow.
Apologies for no picture today, but I have good news instead: we had the best day of drilling since the project started back up again! The new drilling strategy of pumping much less mud into the hole because there’s already a large amount of hydrostatic pressure due to groundwater is working out really well. The drillers made ~105′ of downward progress over the past 24 hours. As a result, the core processing team was quite busy today and we processed 97′ to a current depth of 4874′ below the surface. The final goal for this hole is ~5400′, at this rate we’ll reach it soon.
After spending the last day and a half overcoming some drilling obstacles, we’re coring again and making good progress. In fact, we just received a delivery of rocks totaling ~40′ – and most of it was drilled this morning. We expect a busy day of core processing tomorrow, the drillers have modified their approach and this alternate technique looks like it may boost our penetration rate.
Today the drillers had to trip all the pipe out of the hole. The reason for this was to dislodge some rock that had fallen out of the bottom of the core barrel, which was blocking the next barrel from reaching the bottom. Since the entire drill string had to be brought to the surface, the drillers examined the bit and determined it was time to replace it. Even though it still had a good cutting face, there was significant damage behind the teeth of the bit. In fact, it was probably the poor condition of the bit that led to the problem of some of the core falling out of the barrel in the first place. At the time of this post, the crew is tripping the drill string back into the hole.
As for the core processing side of things, we’ve now processed rock to a depth of 4737′. Today’s 46′ of rock was all pahoehoe and ‘a‘a lava flows, the photo above is another view of the olivine-rich intrusion I posted yesterday.
Drilling continues to proceed pretty smoothly, we processed another ~70′ today. Among that rock was the first intrusion we’ve seen since drilling started up again. If you examine the photo above, you’ll notice a brown shape with a black outline that sort of looks like a large wave about to break. You’ll also notice a lot of light-colored spots inside the wave shape. This is the top contact of an intrusion: the black outline is its glassy margin and the light spots are olivine phenocrysts (as you can see, it’s extremely olivine-rich). The intrusion closely resembles a shallower one that I posted a picture of on this site back on July 18th, I wouldn’t be surprised if they were both from the same olivine-rich magma source. This particular intrusion is about eight feet thick, and toward its base it completely captured some clinker pieces from the ‘a‘a flow it invaded. I’ll try and get a picture of some of that captured clinker to post another day.
Just a quick text update today, drilling is proceeding steadily and we’ve processed core to a depth of 4623′ below the surface. Overall we’ve seen a good mix of pahoehoe, transitional, and ‘a‘a flows. The mineralogy of these units ranges widely, from flows that contain lots of olivine, plagioclase, or both as well as flows without any phenocrysts at all. The most constant feature of the rock we’ve processed over the last two days is most of the fractures are strongly oxidized from water flowing through them. However, despite extensive alteration along fractures, flow interiors are still pretty fresh and suitable for geochemical analysis.
After a lot of obstacles and hard work to overcome them, yesterday the drillers were able to do some core drilling at the depth we left off at back in July. The hole is finally pretty clean of most debris and about as stable as we can hope for. We processed ~70′ of core today (see photo above), to a depth of 4563′ below the surface. Later tonight, we’ll receive what the day shift was able to drill. Our goal for hole completion is to reach ~5400′ depth (sea level), and if everything goes well that will only take a couple more weeks or so. Stay tuned for tomorrow’s update, I’ll be posting updates every day as long as we continue to get rock deliveries from the drillers.