This morning, we were lucky enough to recover some of the material we drilled yesterday, even without having drilled with the inner core barrel. We retrieved a metal piece of the casing shoe and a fist-sized piece of olivine-rich rock. After tripping back into the hole, we injected a slug of cement into the bottom and tried to pump it into the formation. The goal of this is to get the cement to anchor the loose material, which will make it easier to drill through. We may need to inject more cement tomorrow, but soon the hole should be stable enough for core retrieval.
Today we made some progress, we drilled through the casing shoe. We continued to drill most of the day, but made little headway because of the loose, unconsolidated nature of the rock formation at this depth. We circulated mud to try and remove some of this material, but the bit could not advance very much. Near the end of the day, we decided to inject cement into this unconsolidated region to anchor the loose rock in place and make it easier to drill through. We are currently tripping out the drill string, and will inject cement tomorrow morning.
Today we conducted an inclination survey on the lowermost 50 feet of the hole. This survey revealed that the hole in general is inclined six to nine degrees near the bottom, and varies its inclination due to S-shaped bends. These bends could be what exerted so much stress on both the core barrel and stiff rod joints over the past two weeks. Tomorrow we will try coring through the rest of the casing with a five foot long core barrel. We hope that this shorter barrel will be small enough to travel through the bends in the casing unimpeded.
We have become good fishermen here at the drill site, today we retrieved the second mill bit and attached stiff pipe. The bit is still in good shape, but the stiff pipe has been heavily stressed at its joints. Additionally, the stiff pipe has been scraped thin in places by rotating against the newly cut casing walls. We hope that milling the past few days has produced a straighter hole and opened a pathway into the side wall of the bent casing. Tomorrow morning, we will be conducting detailed inclination surveys at the bottom of the hole, and our next course of action will be determined by the findings of these surveys.
We were disappointed today, as we discovered that a stiff rod joint separated again during milling. This is the same joint that broke before, and it was welded back together, but some of the strengh of this connection was lost when its threads were initially stripped. In an attempt to minimize stress on this joint, it was repositioned in the drill string to be 10 feet higher than last time. However, it was the weakest portion of the stiff pipe, and after about 15 hours of drilling, it gave way. The drillers are now tripping back into the hole to fish for the pipe and mill bit. Hopefully we will retrieve them sometime tomorrow.
We proceeded slowly but surely down the hole with our second mill bit today. All the parameters indicate that we are cutting through the casing, but by the end of the day at a depth of 9865 feet, we still hadn't cut all the way through it yet.
As expected, we retrieved our stiff drill pipe and used mill bit today. We immediately replaced it with a new mill bit, one shaped differently and better suited to cut through the side of the casing. By the end of the day, we had drilled to a depth of ~9800 feet. Hopefully we will make it all the way through the casing tomorrow morning.
We hit another snag today, as we discovered that the mill bit and the 10-foot length of stiff pipe it is attached to separated from the rest of the drill string yesterday. It appears that the bit cut much of the casing, but expired before it could get through the bend and into the rock below. When the bit would no longer cut but continued to rotate, it stressed the stiff rod threads until they stripped, and the lengths of pipe separated. We are confident that we have grabbed onto this fish, but will have to wait until tomorrow to recover it at the surface. Then we will attach a new mill bit, weld the stripped rods together, and trip down again to finish drilling through the casing.
We drilled through casing most of the day with the mill bit and stiff rods, until the bit wouldn't cut any more. We won't know for sure if we were successful in our attempt to drill through the side of the casing until tomorrow, when we finish tripping out and retrieving the bit. If necessary, we can continue drilling with another mill bit that will arrive tomorrow morning.
We had a productive Thanksgiving today at the site. Engineer Bruce Howell arrived in the morning with a brand new mill bit and 30 feet of super stiff pipe. The drillers attached these tools to the existing drill pipe and tripped to the bottom of the hole. Tomorrow morning we hope to drill through the side wall of the bent casing, and establish a straighter hole for coring operations.
Examination of last night's downhole data revealed what we expected; the bottom of the casing strays from vertical quite sharply. This has been the cause of our core barrel snags this past week. A mill bit and 30 feet of stiff rods are due to arrive in a couple days, and with these tools we will drill straight down through the casing. In the meantime, drillers will perform maintenance on the drill rig and other site equipment, and the science team will finish preparations for when we receive core.
Our plan today was to survey and cement the bottom of the hole. However, the hot afternoon sun warmed the water used to mix cement just enough to harden it early, before it could be released from the syringe. We will recement tomorrow, and use the downhole surveying tool data collected this evening to determine the best course of action.
Good news, we successfully fished out the core barrel today! Tomorrow we will run surveying tools to the bottom of the hole and try to determine the source of our drilling problems.
We spent all of today day tripping pipe in, out, and back into the hole in search of the core barrel. Our first try at fishing it out was unsuccessful, but indicated that the barrel may have slipped out. After welding grip beads and cementing sand to the inside of our fishing tool, we sent it back down the hole. Hopefully these modifications will allow us to hook our fish tomorrow.
It was a rainy day with little activity around the drill rig. Bruce Howell drove to the other side of the island and worked with a machining shop in Kailua-Kona for most of the day to make a fishing tool to retrieve our broken core barrel. When he returned, the drillers immediately started tripping in the tool and pipe, but will not reach the bottom until tomorrow.
It was another beautiful sunny day in Hilo, but spirits were low at the drill site. On our second attempt to pull up the core barrel, we retrieved only part of it. The barrel was broken by shear forces during drilling of the casing shoe. We will be working with a local machining shop to fabricate a tool to fish it out.
At the end of the day today, we finally caught our fish! The outer core barrel was retrieved after three days of attempts to get it from the bottom of the hole. Tomorrow we will trip pipe back into the hole and resume coring the casing shoe.
Today was a long day of tripping pipe into the hole (7 hours), fishing for the outer core barrel, and then pulling all the pipe back out again (5 more hours). We will know tomorrow morning if the core barrel was recovered or not.
Today, drillers had to pull all the pipe to the surface and fashion implements to fish for the core barrel and associated downhole tools. The inner core barrel was retrieved first, and the outer core barrel by the end of the day. We hope to continue drilling out the concrete casing shoe tomorrow, but may have to repair some of the downhole tools first.
Today, we began to drill into the cement above the casing shoe. At the end of the day, the first run was still at the bottom of the hole due to mechanical issues with the core barrel. It will probably be necessary to pull all the pipe out of the hole, but tomorrow we will retrieve the core barrel and continue drilling.
Today drillers injected 75 gallons of cement out the casing perforations into the surrounding annulus. The cement will harden overnight, and tomorrow it will be assessed whether another batch of cement is necessary. Once the cement is hardened above the perforations, we will begin drilling out the cement inside the casing and down through the casing shoe.
Today drillers struggled to inject sodium silicate into the bottom of the casing in preparation for cementation. Using the new injection syringe has proved more difficult than anticipated, and multiple attempts were made to inject at the correct depth. Cementation cannot begin until this issue is resolved, hopefully by tomorrow.
Today drillers placed a custom-made syringe for injecting cement into the hole. They also had to fix a problem with the wireline winch, so cementation did not begin. We hope to cement the bottom of the casing tomorrow.
Today, water was pumped into the drill hole at a variety of depths in order to flush out old drilling mud deposits that had settled to the bottom. Circulation out of the perforations was achieved, and we hope to cement the bottom of the casing tomorrow or Monday.
Today pipe was tripped in all the way to the bottom of the casing, ~9,800 feet. The hole was then flushed of old mud, and new drilling mud was pumped in for drilling lubrication. However, fluid pressures in the hole are very high (600-700 psi), and chief engineer Bruce Howell will apply a variety of techniques to reduce this pressure before drilling through the casing shoe.
Today drillers flushed the hole of mud and then tripped in 30-foot lengths of drill pipe to a depth of ~7,000 feet. Also, a large bulldozer was used to empty out the mud sump next to the rig. The science team is working on setting up additional rock processing and storage space for when coring begins.
Today drillers spent all day tripping in about 4000 feet of pipe. Yesterday's perforation of the casing failed to establish circulation for cementation, so we are planning to cement after drilling through the casing shoe.
Today the casing was perforated with specialized explosives at a depth of 9770-9780 feet. We are testing the downhole circulation after perforation to determine if additional perforations are necessary before we attempt to cement the casing in place.
This morning there was a blessing ceremony for the drill rig and project. Hopefully with Pele's support, all drilling obstacles can be overcome, beginning with tomorrow's perforation of the casing.
Today a camera crew, making earth and planetary science educational videos, visited the site. Co-Principal Investigator Don Thomas explained the background, scientific objectives, drilling techniques, and other details of the project.
Today the top drive, the main component of core drilling, was moved into place on the drill rig. Also, the geophysical logging trailer with its wireline winch was set up behind the rig for future downhole investigations.
Today the project sign was placed at the entrance to the project and drilling setup continued. The drillers have assembled lights on the rig so they can work into the early evening, and in preparation for around-the-clock drilling once coring begins. Heavy rains here at sea level in Hilo meant the first snow of the season atop Mauna Kea, visible from the drill site (see additional photos).
There was a lot of activity at the drill site today. With a crane on site, the mast of the drill rig was raised and the heaviest equipment was moved into place. Setup is proceeding smoothly as the drillers have begun to arrive.
We're done. We spent a good part of today in the broken and unstable zone at around 9800' - 9900'. This was the rattiest zone we've had to drill through for the entire hole opening effort and it seemed to want to grab the bit at every opportunity. We spent about four hours just rotating on bottom trying to grind rubble and flush cuttings out of the hole. Although we generated a small mountain of cuttings, whenever we put weight on bit, the drill string would bind. After a half dozen of these sticking episodes, Bruce and I decided that we had had about as many warnings as anyone deserves. We talked over the options, and it was pretty clear that the deeper we drilled into - or even past - this unstable zone, the greater was our risk of permanently "planting" the drillstring in the hole. Under the circumstances, we decided that the prudent course of action was to declare hole opening complete and get out of the hole while we still could. Although we were not able to get down to the solid interval of pillows below the bad zone, we believe that, when we do the casing job, we can go in with a cutting shoe on the bottom of the 5" casing and wash and drill down to the solid formation. Even if we can't, that is preferable to getting the drill string stuck and having to spend a lot of time and money trying to retrieve it or work around it. So, this will be the last update for a while - at least until we get back underway to set casing after the logging program is complete.
I guess I owe everyone an apology for not posting an update for two weeks - and it's been a tough two weeks. The cementing that we did in the shallower intervals of the hole seems to have held pretty well but, as we continued opening hole toward 9000', we encountered several more formations that were determined to flow on us. We were seeing pressures - when we shut everything in - of more than 10 bar even with heavy mud in the hole. We proceeded to do additional cementing jobs in three zones - two at depth and a shallower one that we had missed earlier - and had the flow under control as we drilled out the plugs. ...
We have made reasonable progress after getting back to bottom and starting to open new hole. However, the pillow interval below ~8600' proved to be some very tough rock. We don't know why this should be so because it appears to be no different from the pillows above, but the drilling rates dropped to as low as two to three feet per hour in parts of this interval. Nonetheless, we made it to about 9100' (2774 m) as of mid-day yesterday but then we hit a lost circulation zone in the rubbly pillows. Then, just below that, we encountered another pressurized zone that came after us. Because the bit was pretty worn, we elected to pull out and do another cement/re-drill routine - that process is currently underway right now. There was some hint in the wear pattern of the last bit that we might have jumped out of the core hole - as soon as the current bit comes out, we will evaluate it to see whether it looks the same. In any event, we are planning to run a single-shot deviation tool with each bit change so we can monitor the hole angle.
During the last several days we placed several cement plugs in the upper interval of pillows (1990 - 2130 mbsl) and drilled them out again. It appears that our efforts were successful in reducing flow from those formations. We then drilled out several other cement plugs that were placed deeper in the hole and made it to the bottom of the opened section yesterday without major incident. We drilled on bottom for the balance of the day and through last night with a much lighter mud - with no downhole pressure problems and not much mud loss into the formation. Barring any major pressure zones below us, we should be able to make reasonable progress to our projected casing depth. At the present moment, the hole is at a drillers depth of 8594' (2619 m) and we are tripping out of the hole to replace the bit.
The downhole pressure problems have persisted. Although I'm looking forward to the opportunity to study these aquifers and their completely uncharted behavior - for the moment we've decided to take the kid gloves off and go after them to shut them down. After a good deal of discussion, it looks like the most effective way to combat the pressure is to cement back the hole that we've opened - and do our best to push cement back into the formations producing the water flow - and then re-drill. There may be more frustrating exercises than drilling a hole and filling it up again so we can re-drill the same hole - but I can't think of what they might be at the moment... More seriously, we've tried "treading water" with control of formation pressure with mud weight, but we are in danger of drowning if we can't get a handle on it. Although I didn't see the flow the other night, from it's description by Bruce and the crew, we could have had 4000 - 5000 gpm coming out of the hole - but, of course, no one was standing around with a bucket trying to measure it. As of right now, we've cemented back to near the bottom of the casing and will probably do one more cement placement before we are ready to begin the drill out process. Stay tuned
On their return invitation on Friday, our friends from Halliburton were able to get a good cement seal on the shallow casing break. We spent Friday night waiting for the cement to cure and Saturday was spent drilling the residual cement out of the casing. We tagged the deeper cemented zone at the top of the 7" casing and, after we drilled through, we had major water flow from downhole. The crew spent most of Saturday night getting it under control with heavy mud and today, Sunday, we are now on bottom back to drilling. We're hoping that we can maintain control on the flow from here on out and maybe get some more hole drilled in the next few days. I should also add that we just got the invoice for the Halliburton work - and I now have a new appreciation for the expression "shock and awe".
It's been a tough couple of days. We've continued to have problems with the deeper water zones that seem determined to spit mud and water at us at every opportunity (see night photos of mud geysers on the rig floor). Part of our problem is that a leak in the shallow casing prevents us from controlling our mud pressure in the wellbore. We decided to try to correct this with a cement "squeeze" and called in our expert (expensive) friends from Halliburton to do the job (see photos). After an impressive performance of slicing and dicing and mixing and pumping yesterday evening, we came back to the site this morning to find our leak alive and well. We're going to give them one more shot at it - and if that doesn't work, I'll be pleased to offer them one-way tickets to another, somewhat more challenging Halliburton job I recall hearing about. We are presently at 8500' and holding. -Don Thomas-
Drilling continues reasonably well. We are now at a depth of ~8260' and pulling the drill string to replace the worn bit. We are still having problems with formation pressures (see photos). Pretty much every time we pull the string we are getting water flow of 1000 gpm or better if we don't take measures to control the flow with heavy mud. We are using cottonseed hulls now for LCM and mixing a heavy "pill" of mud every time we pull the drill string. Although we are still losing some mud, it seems to be a workable arrangement. We are now at a depth of 8260' (2517 m).
We are back to making good progress with hole opening and it looks like we may have the water flow problem (at least partially) under control. On Thursday, we were able to run two sweeps of lost circulation material (a paper based product) through the system and that seems to have slowed down the loss of drilling fluids through the permeable pillow intervals that were giving us problems. Drilling through the hyaloclastite interval from 2130 m to 2230 m went fairly fast. The pillow intervals seem to be more difficult to drill and the massive unit at 2312 m has proven to be tougher yet. We tripped yesterday afternoon to change the bit. We are now at a depth of 7612' (2320 m).
The interval of pillow lavas at ~2000 m has continued to challenge us. We are having difficulty finding a balance point for the formation pressures - at too light a mud weight, the hole will begin to flow; at a slightly heavier weight, we begin to lose mud into the formation at a very rapid rate. Either way, we are burning through our mud supply much faster than we would like. We are going to try to send some lost circulation material (paper or possibly cotton seed hulls) into the hole to see if we can't plug off some of the zones that are taking fluids. If we can pack off the lost circulation zones, it will let us maintain the mud weight on the higher side to keep from having to fight the formation pressures as we go deeper. We are currently at about 2100 m.
We are gradually moving into a routine. Last night we began tripping out of the hole to change the bit - apparently it was a good decision, the bit had about had it (see photo). The buttons are about gone on the drilling faces and the bearings are also very loose. The hole was at a depth of 6600' when the bit was pulled. After spending this morning tripping back into the hole, we are now on bottom and drilling.
We are beginning to make some progress on opening the hole - we are now below 6300' and continuing to make good progress. We've had a few of the expected hang-ups with shaking down the equipment. Most have been fairly trivial that have cost us an hour here and there, and a few others that can be deferred until we have some down-time to deal with. We even got some sun, finally (see attached). However, it looks like la Nina (the aftermath of el Nino) is going to be a wet one for Hilo - we've probably had a foot of rain since the rig arrived. I may not have mentioned earlier that, when the mast went up, we were able to re-install the microwave link to the UH-Hilo campus so that we can now send and receive e-mail at the site. And, for future reference, we have a Post Office box to which snail mail can be sent: HSDP P.O. Box 5073 Hilo, HI 96720
The big day has arrived - we have completed the detail work of getting the rig set to go and we are now going into the hole to begin the hole opening exercise. Although the remedial work on the casing will still have to be done, it turned out that Halliburton wasn't scheduled to be on the island for another couple of weeks and, rather than pay a very high premium to mobilize them out here just for a one-day job, we decided to defer the corrective work until after they get here next month. We should be able to take a break from drilling some time in May and have Halliburton come in to do the work, and get back to hole opening with minimal wasted time and resources. By the end of the day today we should be at 6000' and making progress on the hole opening work.
