Report Numbers: SAND-78-0443C; CONF-780708-1; OSTI ID: 6700728The scientific feasibility of extracting energy directly from buried circulating magma resources is being assessed. One of the tasks of the project is the study of geophysical measuring systems to locate and define buried molten rock bodies. To verify the results of a molten rock sensing experiment performed at Kilauea Iki lava lake, it is necessary to drill a series of holes through the solid upper crust and through the molten zone at that location. Thirteen holes have been drilled in Kilauea Iki. The results achieved during the drilling of the last two holes indicated that the molten zone in Kilauea Iki is not a simple, relatively homogeneous fluid body as expected. The encountering of an unexpected, unknown rigid obstruction 2.5 ft below the crust/melt interface has led to the conceptual development of a drilling system intended to have the capability to drill through a hot, rigid obstruction while the drill stem is immersed in molten rock. The concept will be field tested at Kilauea Iki in the summer of 1978.U.S. Department of EnergyDOE Contract Number: EY-76-C-04-078

Colp, John L.

Okamura, R.T.

ScholarSpace at University of Hawai'i at Manoa

Drilling into molten rock at Kilauea Iki

eVols at University of Hawaii at Manoa

S AAJtr-7 p-{)¥~C­c..o~ p~ 7i>070 f -~ 'fDRILLING INTO MOLTEN ROCK AT KILAUEA IKI.. -- y;:.I-IIII'Vf .':'. i' ' .........~...John L. Colp. Sandia Laboratories t Albuquerque, Mot 87115Reginald T. OkamuraU.S. Geological SurveyHawaii Volcano Observatory_----NOTICE:----....,lbiI IIPOrt _ prepmd ... _, of workIJIClIUO"d by tile United State. \iooemmenL Neither tileUnited State. nor the United Slltel Department or1!ne'IY' DOl any of their employees, DOl any of dleirCOOl_OIl, ",bcontractoll. or their employ.... -any warrantyI. exprell or Implied, or aaumn lIlY leplUobUity or nsponsibDity for die _<Y. compIe-or Ulefulneu of lilY iIIfonration. appantul. product orprocell diIclOled. Of .pmentl that ItI _ would IlOlIofrinp pri..,ely .....d ri......ABSTRACTThe Sandia Magma Energy Research Project isassessing the scientific feasibility of extract..ingenergy directly from buried circulatingmagma resources. One of the tasks of the projectis the study of geophysical measuring systems tolocate and ·defineburied molten rock bodies. ToverifY the results of a molten rock sensingexperiment performed at Kilauea Iki lava. lake, itis necessary to drill a series of holes throughthe solid upper crust and through the molten zoneat that location. Thirteen holes have beendrilled in KilaueaIki; eleven by other groupsand two by Sandia. The results achieved duringthe drilling of the two Sandia holes have indica-ted that the molten zone in Kilauea Iki is not asimple, relatively homogeneous fluid body asexpected. The encountering of an unexpected t un-known rigid obstruction 2.5 ft below the crust/meltlnterface has led to the conceptual develop-ment of a drilling system intended to have thecapability to drill through a hot t rigid obstruc-tion While the drill stem is immersed in moltenrock. The concept will be field tested at KilaueaIki in the su:nmer of 1978.The lava lake 1n Kilauea Iki crater located inthe Hawaii Volcanoes National Park on the islandof Hawaiit still molten since the 1959 eruption,was chosen as the site fora Lava. Lake SensingExperiment sponsored by Sandia in early 1976.The eva.luationof. the abilities of the va.riousgeophysical sensing systems used in that exper-iment to correctly detect and define the buriedbody of molten rock requires the dri~3tng oraseries of holes into and through it. Permis-sion was granted by the National Park Service forSandia a.nd the USGS Hawaiian Volcano Observatory(HVO) to drill a series of 15 confirmation holes.Two holes of this series were drilled through150 feet of the upper crust and into the moltenrock in 1976. The drilling of these holes andthe problems encountered are described in thispaper.PREVIOUS KILAUFA IKI DRILLIOO EXPERIENCEThirteen holes have been drilled through thecrust of·Kilauea Iki lava. lake since its fillingin 1959. Table I lists the sequence, number andsize t a.ndthe depth at which melt was reached.16.019.029~735.041.643.685.085.087.0145.0149,3Depth toMelt (ft.)*Number &Dia. ( in.)1-1 3/161-21-1 3/161-1 3/161-1 3/161-31-3 .1-33-32-3Date4-8/601/604/6110/615-6/6212/623/675-7/67·10/672-3/758/76TABLE IHoles Drilled Into Kilauea Ild«·Deepened h~le drilled i~ 4/61INTRODUCTIONWork performed under the auspices of theU.S. Department of Energy, Contract No.AT{29-l )-789· .Sandia Laboratories interest in drillinginto molten rock(i~ems trom the Magma EnergyResearch Project presently being conductedunder the Department of Energy/Division of EasicEnergy Sciences sponsorship. The objective ofthis project is to assess the scientific feasibil-i ty of extracting energy directly from buried .circulating magma resources. One of the tasks of'that project is the developmentt demonstrationtand verification of exploratory techniques forlocating and defining buried molten rock resources.In March 1975, a workshop cosponsored by Sandiaand the U.S. Geological Survey. of about thirtyscientists was convened to assess the presentstate of knowledge on magma 't~' to recommendcritical needs for research. A major recom-mendation of this group was to evaluate geophysi-cal techniques over a "known" molten rock body.J .~. Corp, ~ !!.:t'- ."- -...-,:. "( -..... In. JU1Y..,t960, the Lawrence Radiation Labor-~ atory (LR1;, now Lawrence Livermore Laboratory,drilled one hole into Kilauea Iki to establish• the thickness of the crust, obtain volcanological~ data, and to test drilling techniques into moltenrock. Standard core drilling techniques wereUSed. Compressed air was used as a drillingfluid at rock temperatures up to 850oC. Waterand air/water ~tures were used for rock temper-atures t~ l050C. The crust-melt boundary wasencountered at 19 feet and the drill bit waspushed down an additionH)foot into the melt.Core recovery was poor.In the three-year period immediately afterthe filling of Kilauea lid, the u.s. GeologicalSurvey eore drilled four holes through the crust.The objective of these boreholes was to conductpetrologic and thermometric studies of a semi-enclosed body of slowly cooling basalt.The first HVO hole penetrated the crust inAugust 1960. A 1 3/16-inch diameter portablecore drill powered by a ~-hp gasoline enginewas used. The specially fabricated drill bitsconsisted of tungsten carbide cutters set in ahigh temperature matrix. Core was collected ina conventional thin-wall, 2-foot double-tube corebarrel. (~Ually pumped water was used as acoolant.The second (4/61 and 10/61) hole drilled byINO used the same portable drilling equipment.previOusly described. Immediately after theOctober penetration a stainless steel-ceramicprobe containing athermocouplt4~s forced 4 feetinto the melt below the crust.The third INO hole (May-June 1962) wasdrilled using the same drilling equipment. An .unsuccessful attempt to push a 10-foot probe intothe melt resulted in the freezing and abandonmentof the probe and 15 feet of drill rod. Thefourth INO hole (12/62) used more powerful drill-ing equipment, a 9rlijportable drill and a3-: hp water pump. The melt interface wasencountered at 43.6 feet.Three holes were· drilled by INO in 1967.The objectives were to measure the crust thick-'. ness and obtain cores for petrologic studies.The equipment used was· a commercial diamonddrilling rig using A-size drill rod and a .5-footlong NX-size (approximately3-inch diameter)corebarrel~Hole67-1 was drilled in March andthe upper crust-melt interface was reached at adepth of 85 feet. Core recovery was 9~. Hole67-2, drilled in May to July, reached melt again.at 85 feet and core recovery was 83~•. Hole 67-3was drilled in October,reached me~6)at 87 teet,and 9~ of the core lr.'&srecovered.The next series of holes were drilled by.HVO in February and March of 1975 using the sameequipment. Hole 75-1 drilled adjacent to 67-3reached the upper crust/melt interface at adepth of'144.5 feet. Hole 75-2, adjacent to67-1, reached the melt interface at 139.5 (*1)ILfeet. Hole 75-3 was drilled near the outer edgeof the crater at a location expected to be out-side of the molten lens. It turned out thatthe hole location was still over the molten lensand the melt interfafg)was en~ountered at adepth of 144.7 feet.CURRENT KIUUEA IKIDRILLING PROGRAMThe first series of geophysical measurementsof the Sandia Lava Lake Sensing Experiment wereperformed in the Spring of 1976. Preliminaryanalysis of the data indicated that eitherseveral of the physical properties of the moltenrock were different from those expected or thethickness of the molten lens was about one-third of that obtained from thermal coolingcalculations. This result instigated an imme-diate attempt to drill a diagnostic hole toextend completely through the molten lens'~earthe center of the lake; presumably the thickestpart of the melt. Two methods of penetratingthrough the melt based on the extensiveexperi-ence on lava lake drilling gained by the USGS/INO were proposed. They were: (1) drill throughthe upper crust to the solid/melt interfaceusing adequate cooling water, then shut off thewater flow and let the drill string fall or pushit to the bottom crust of the molten zone: and(2) drill through the upper crust to the solidImelt .interface and then with maximum flow ofcooling water chill a solid zone below the bit,drill to the melt, chill a solid zone below,and repeat that sequence until the bottom crustwas' reached.Type 316 stainless steel pipe (3! inchesoutside diameter, 2 7/8 inches inside diameter,110 feet long) was obtained and threaded with'standard pin and box threads to match NW casing.Two special carbide insert core bits to matchthe stainless steel pipe were fabricated. Thesebits used the standard carbide insert matrixsince it was planned to water cool this bitwhile drilling 1n the upper crust. A Sandiacontract was negotiated with a commercial drillerto turnishadriU rig, equipment,and drillingcrew. R. Helz, USGS Reston, logged the hole asdrilled, evaluated the cores obtained, and isperforming core analyses at their laboratory.The drilling of hole KI 76-1 was started onAugust 18, 1976. It was located 15 feet south oflocation l7N2 on the lava lake surface. Thesolid/melt interface was reached on August 24 ata depth Qf 149.3 feet. Core recovery was 991,of rock drilled. The core barrel dropped 0.7feet into the melt before it was retrieved. Onthe following day the stainless steel drillstring with the special core bit was assembledand placed down the hole. "Drilling was startedat 145 feet depth with the volume of coolingwater controlled to an amount previously calcu-latedtojust boil when it reached the drillingle~l. Molten rock was encountered at about149 feet, the cooling water flow was stopped.at the sUrface, and the drill string was pushedby the drill rig feed cylinders a distance of. The drIlling of hole KI 76-2 was started onAugust 30, i976 , using the same sequence andequipment down to the solid/melt interface thatwas used on the first hole. Core recovery was98% on thIs hole. The solid/melt interface wasreached at 149.9 feet on September 2. At thatpoint the drill bit was raised ten feet andcooling ~~ter was pumped downhole for 20-30minutes before pulling the drill string.The following morning the drill string wasreplaced in the hole using a 10 foot NX rigidcore barrel with a standard carbide insertNXbit. Bottom hoie temperature was measured,befose drill string insertion, to be l7l8°F(944 C). Drilling started at 141 feet depth.The water pump was running at its maximum nowrate at - 100 pd•. The. drilling crew and obser-vers were alerted to observe the first change indrilling or water now conditions so that thedrill string could be lifted immediately toallow cooling water to chill the molten rockahead of the bit.The first observed indication of a changein drilling conditions was a surging and pressurebuild-up of the cooling water system indicatingnow blockage. This occurred at 147.1 feet depth.The drill string was raised a few feet but thenow blockage continued. After a short whilethe drill string was removed and the drill bitwas found to be totally blocked with quenchedglass from the molten rock. This material wasremoved from the bit and core barrel, andthe bit was still in good, usable condition. Thedrill string was replaced downhole and encounteredsolidified ooze at 143 feet depth. Again, thedrilling crew and observers were cautioned to bealert to any surface indications of changes indrilling conditions that would mean molten rockwas being encountered. As in the earlier attempt,the first surface indication was· a surging andpressure build-up of the cooling water systemindicating flow blockage. This occurred at147.8 feet depth. The drill string was removedand the core bit waS found to be blocked withchilled glass from the molten zone. This timethe bit was d8Jllaged such that it was not reusable.The depth to the top of. the solidified oozewas measured at 136.3 feet. At this time, the·decision was made to stop further drilling. Therationale behind this decision was: (1) thecarbide bit waS damaged and unusable; (2) maxi-mum now and pressure from the cooling watersystem available had been demonstrated twice tobe i!18.dequatetoprevent the molten lava underits geostatic pressure frem nowing into andblocking the core bit; (3) an alerted, exper-ienced drilling crew and observers had beenunable on two occasions to discern on surfacewhen the .molten rock was being encountered; and(4) the planned expenditure of time and moneyfor that .year •s drilling program .had been· expended.The following morning the solid materialthat had oozed up the hole overnight was measuredat 1~5feet6 The downhole temperature was1760 F (968 c). The drill rig was started todrill out the ooze to a depth of 148 feet, afterwhich the stainless drill string with the steelpenetrator point in place would be inserted tohammer into the melt and the underlying obstruc-tion•. However, the diamond drill bit encounteredan obstruction downhole at 138 feet. Afterunsuccess:f'ullyattempting to grind.out theobstruction at the expense of one diamond core. bit, it was assumed that the obstruction must bethe missing part of the core bit. Apparentlythe lower end of the bit had beennaredoutconsiderably during the previous day's hammeringbut had remained together as it was retrieveduntil it reached a portion of the borehole thatwas cool enough (non-plastic) to wedge it andcause the observedfallure at the thread root.After deciding it was not practical to continue.drilling,hole KI 76-1 was abandoned and thedrill rig was moved a.bout Ii feet south tostart anew hole.The drill· stri~ was removed. ..It was obser-ved that the lower 1'2 inches of the drill bit hadbroken off at the root of one of the box threadsthat attached it to the stainless steel pipe.If the broken part of the bit was left at thebottom of the hole, it might prove little or noobstruction to the penetration point.On the following morning the depth to thesolid that had oozed up inside the drill stringwas 1~4feet and the temperature was l8450 F(1015 C). The drill rig was connected back tothe drill string and could rotate and raise itbut could not pUsh it deeper. It was assUmedthat the matrix holding the carbide insertsin the core bit had melted so that no cuttingsurfaees were available. However, it was thoughtthat the remaining part of the bit might be ableto be. forced through the obstruction on Which it. was resting. Accordingly: a 300 pound hammer witha fall-distance of 30 inches was installed on topof the drill· string. After 30 minutes of hammer-ing, no progress of the drill string through theobstruction below was observed. It was decidedto remove the drill string, replace the bit witha hard steel point and attempt to penetrate theobstruction.Real1zingthat there was an unexpectedobstruction lying about.2.5 feet below the crust/melt interface that was less plastic (more rigid)than the steel drill stem at the same temperature,it was decided to use the second proposed methodfor piercing the molten region, namely, chillingthe melt ahead of the bit and then drilling.. -through it.....;1- .... -.~. t.5 feet ilU<> the Illelt where progress was st¢pped. - . ~ .by an unCl:XPected obstruction. At the same time,the drill string was frozen in the melt so thatno movement, rotational or vertical, was possible.Everything was left· as it was until the nextmorning to determine if the drill pipe wouldw.rm up enough to thaw the lava frozen around it.;• .r' CONCW~IONS~ .... "-'; - {The early (1960-1975) experiences in drillinginto Kilauea lki had been considered successful~ since they had achieved their objectives, i.e.,• determining crustal thickness and obtaining coresamples for laboratory study•. However, none ofthese drillings had penetrated an appreciabledepth into the molten rock.The ~andia/HVO experience in 1976 had notachieved its objective of drilling through themolten zone. Although the drill did penetrate2.5 feet of the melt, an unexpected and unknownobstruction prevented a complete transit to thebottan of the molten zone. However, the crustalthickness was determined, very complete core·sections of the upper crust were obtained for~trologic studies,· and the fact that the moltenlens as it existed at the location drilled wasnot a simple, relatively homogeneous liquid asexpected was established.Future plans include the following: First,the· need to verify the geophysical measurementsof the Lava Lake Sensing Experiment still remains.Also, it is apparent that much infonnation needsto be gotten to understand the present verticalstructure of the molten zone of the lava lake.Finally, a drilling system to achieve the abovemust ha~e the ablUty to drill through very hot(-1050 C) rock while the drill stem is immersedin molten(- 10750 C) rock.Immediately after the completion of the1976 drilling series, the Lava Lake DrillingProgram was initiated at Sandia to develop andbuild a drilling system that would accomplishthe above. The in!tial concept·selected fromthis program for development employs a double-tube, insulated drill stem and a Mar-M 509 dragbit. High pressure air will be used to cool theinner drill stem and c1.ear the cuttings from thebit when drilling in the molten zone. This con-cept will be field tested at Kilauea lki in thesummer of 1978.Geological Survey Professional Paper 537-B,1966, p. 26.5. D. E. Rawson and W. P. Bennett, Results andPower Generation Irnnlicati~ns from Drillinginto Kilauea Iki Lava Lake, Hawaii, UCRL-6374, Lawrence Radiation Laboratory,Livermore, CA, 1961, p. 31.6. Unpublished drilling logs, U.S.G.S. HawaiianVolcano Observatory.1.2.3.J. L. CoIl', and G.E. Brandvold, "1be SandiaMagma !:nergy Research Project ," Proceedings,Second United Nations Symnosium on the Develop-ment and Use of Geothermal Energy, SanFrancisco,l976, ;pp. 1599-1607.J. L. CoIl', et al., Ma$;lllA Workshop Assess-ment and RecOIl::lendations, SAIID 75-0306,Sandia LaboratorIes, Al.buquerque, Moi, 1975,p. 44.J. F. Hermance, D. W. Forsyth, and J. L.·Colp,A Critical Assessment of GeonhysicalSensingExperiments on Kilauea lki Lava Lake,SAND 77-0828, sandia Laboratorles,Albuquerque,EM, 1978.D. H. Richter and J. G. Moore, "Petrology ofthe Kilauea lkiLe.va Lake, HaWaii," U.S.

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Drilling into molten rock at Kilauea Iki

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