View metadata, citation and similar papers at core.ac.ukbrought to you byCOREprovided by UNT Digital LibraryIndependent Technical Investigationof the Puna Geothermal Venture UnplannedSteam Release, June 12 and 13, 1991Puna, HawaiiFor:.The Honorable Lorraine R. Inouye, MayorCounty of HawaiiandThe Honorable William W. Paty, ChairpersonBoard of Land and Natural ResourcesPrepared by:Richard Thomas, Dick Whiting, James Moore and Duey MilnerJULY 1991
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RTABLE OF CONTENTSExecutive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Introduction .Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Investigation Team Members .Persons Interviewed by investigation Team .Geology .Drilling Permits and Inspections .General Drilling Program at PGV Location .Well KS-7 Blowout Incident .Drilling Activities on Well KS-8 Prior To, During. and After the Blowout . . .Well KS-8 Drilling History .Current Status of Well KS-8 .Analysis of Shallow Subsurface Geologic System(Surface to 2000') .Analysis of the Deep Kick in KS-8 .Analysis of Blowout Equipment .Supervisory Personnel.Recommendations .Recommendations for Upper Portion of.Well(Surface to 2000') .Recommendations for Equipment Modifications and Additional Equipment . .Recommendations for State Regulatory Agencies . . . . . . . . . . . . . . . . . . .Recommendations for Supervisory Personnel .General Comments on the PerxniVFtegulatory Process . . . . . . . . . . . . . . . .Conclusion .G1oss;uvofDrillingTerms.Appendix A .Figures 1 to 10Appendix B .Drilling History Between May 1. 1991 and June 6. 19911333455666610111112131313141516161617f.
. .On June 24, 1991,a third-party investigation team consisting of Richard P.Thomas, Duey E. Milner, James L. Moore, and Dick Whiting began an investigation intothe blowout of well KS-8, which occurred at the Puna Geothermal Venture (PGV) site onJune 12, 1991,and caused the unabated release of steam for a period of 31 hours beforePGV succeeded in closing in the well.The scope of the investigation was to: (a) determine the cause(s) of the incident;(b) evaluate the adequacy of PGVs drilling and blowout prevention equipment andprocedures; and (c) make recommendations for any appropriate changes in equipmentand/or procedures.This repon finds that the blowout occurred because of inadequacies in PGVsdrilling plan and procedures and not as a result of unusual or unmanageable subsurfacegeologic or hydrologic conditions. While the geothermal resource in the area being drilledis relatively hot, the temperatures are not excessive for modem technology and methods tocontrol. Fluid pressures encountered are also manageable if proper procedures arefollowed and the appropriate equipment is utilized.A previous blowout of short duration occurred on February 21, 1991,at the KS-7injection well being drilled by PGV at a depthpfsrpproximately 1600'. This unexpectedincident alerted PGV to the possibility of encountering a high temperature, fractured zoneat a relatively shallow depth. The experience at KS-7 prompted PGV to refine itshydrological model; however, the drilling plan utilized for KS-8 was not changed.Not only did PGV fail to modify its drilling program following the KS-7blowout,but they also failed to heed numerous "red flags" (warning signals) in the five dayspreceding the KS-8 blowout, which included a continuous I-inch flow of drilling mud outof the wellbore, gains in mud volume while pulling stands, and gas entries whilecirculating muds bottoms up, in addition to lost circulation that had occurred earlier belowthe shoe of the 13-3/8-hch casing.While there was nothing unusual about encountering a large fracture at a depth of3476', especially in light of the drilling experience at KS-7,it was clearly unusual andinappropriate under the circumstances for PGV to be drilling KS-8 at that depth with amud weight in excess of 10.6 lbs/gal. When the bit encountered the fracture, the heavydrilling mud probably entered the fracture, leaving the well bore partially void of confiningfluid, thus allowing steam, gases, etc. from the fractures to enter the well bore, producingthe "kick" that led to the blowout.The decision made by PGV personnel on June 12th to continue to drill to 4000'before setting 9-5/8" casing should not have been made. The casing string should havebeen set at 3177' and cemented to surface in order to seal off the fluids attempting toflow into the well and to sene as a good anchor for additional blowout preventionequipment prior to drilling ahead.
While not the cause of the blowout, PGVs drilling supervision prior to the kick wasinadequate in light of the indications that KS-8 could become a problem well.PGV personnel took appropriate steps to control the well following the kick.However, there were certain inadequacies in PGVs drilling operations and blowoutprevention equipment. The mud cooler being used was inefficient. Monitoring equipmentwas not strategically placed. A sufficient supply of cold water was not available to pumpinto the wellbore to properly kill the well in the event of a blowout. The choke line wasnot of sufficient diameter to handle the volume of fluid that had to be vented, and therewas no silencer on the end of the choke manifold line to reduce noise.The investigation team recommends: (1) substantial changes in PGVs drillingprocedures and supervision; (2) several equipment modifications; and (3) significantimprovements in regulatory oversight. The investigation team concludes that if therecommendations presented in this report .are implemented, drilling geothermal wells inthe Kilauea East Rift Zone may proceed safely. This conclusion is limited to the scope ofthis investigation which pertains only to the technical aspects of geothermal drillingprocedures and equipment.2
INTRODUCI'IONOn February 21, 1991, a blowout of short duration occurred on the KS-7 injectionwell being drilled by Puna Geothermal Venture. On June 12, 1991, another more seriousblowout occurred on KS-8.Subsequent to the events, the State of Hawaii and the County of Hawaii requesteda special investigation team named below to: (a) determine to the best of the team'sability the cause(s) of the incident; (b) evaluate the adequacy of PGV's drilling andblowout prevention equipment and procedures; and (c) make recommendations forappropriate changes in equipment and/or procedures.Note: To help the non-technical reader, this report includes a simplified holecirculating system diagram showing monitoring device locations (Fig. l), a simplifiedBOPE configuration diagram (Fig. 2), and a glossary.APPROACHThe investigation team anived on the Big Island on the afternoon of June 24,1991. The team decided to: (1) request and review documents from Puna GeothermalVenture, including but not limited to summary reports, mud logs, tour reports, directionaldrilling information, and mud reports; (2)interview key personnel and other people withinformation considered "key"; and (3) visit the site both on the ground and in the air.Because of the short time frame for carrying out the investigation and preparing thereport, it was decided not to expand on the team's specific obligations.I.In general, Richard Thomas and James Moore took the lead in investigatinggeologic, hydrologic and permitting aspects, while Duey Milner and Dick Whiting took thelead in investigating drillingprocedures, and equipment aspects. All of the team membersagree on the contents of the report, which indudes infomation from the many sources.INVESTIGATION TEAM MEMBERS:Richard P. Thomas, Team Leader, Geothermal Officer, State of California Department ofConservation, Division of Oil and GasDuey E. Milner, Geothermal D d h g Supemisor, Independent ContractorJames L. Moore, Senior Vice President, Natural Resources, California Energy CompanyDick whiting, Resource Engineer, State of Nevada, Department of Minerals3
. TbPERSONS INTERVIEWED BY INVESnGATION TEAMMaurice A. Richard, Regional Development Manager, PunaGeothermal VentureNorman J. Clark, Project Manager, Puna GeothermalVentureWilliam J. Teplow, Field Manager, Puna GeothermalVentureTeny L. Crowson, Drilling Superintendent, PunaGeothermal VentureRoger Hankon, Reservoir Engineer, Consultant for Puna Geothermal VentureTom Jones, Operations Manager, Parker-Drilling CompanyMark Andrews, Tool Pusher, Parker DriUing CompanyBill Earles, Driller, Parker Drilling CompanyJohn Bishop, Demckman, Parker Drilling CompanyDale Henewing, Motorman, Parker Drilling CompanyClement Kalung, Floorman, Parker Drilling CompanyJ.D. White, Mud Engineer, BaroidB.J. Livesay, Consultant, Livesay IncorporatedMike McLaughlin, Mudlogger, Tecton Incorporated (ExLog-Smith)Eric Tanaka, Geothermal Technician, Department of Land and Natural ResourcesChauncey Hew, Geologist, Department of HealthJim Kauahikaua, Geophysicist, U.S.G.S.Richard Moore, Geologist, U.S.G.S.Frank Truesdell, Geologist, U.S.G.S.4
GEOLOGYHigh temperature geothermal resources are known to be contained within the EastRift system of Kilauea volcano in the Puna area of the Island of Hawaii. Although hightemperature geothermal resources may be present within other rift zones on the Big Islandand the specific geology of such other rifts zones strongly suggest this,the presence ofsuch resources has not been confirmed by drilling.The East Rift system of Kilauea is defined as a relatively straight feature extendingin a NE by SW direction along the lower seaward flanks of the volcano and extending atleast 20 kilometers out to sea.At the surface, the rift is characterized by a linear expression whose width mayvary from one-half to one and one-half miles. Abundant evidence in the form of recentvent deposits, flow rocks, and altered rock within and along the rift, indicates that the riftis plumbed into the Kilauea volcanic system. Eruptive events along its mace tend to cycleevery 10 to 15 years and can range from simple, quiet flow events to somewhat explosivevent displays.Hydrologically, the rift most probably intercepts a large portion of the sub-surface,down-slope water flow. Some water is effectively dammed in its southeasterly flow to theocean and carried in a northeasterly direction, still down along the hydraulic gradient butparallel to the rift zone. Some of this groundwater undoubtedly finds itself within theplumbing of the rift zone, where it becomes part of the geothermal system.Within the rift zone, the rocks are generally characterized as volcanic products withdivergent modes of on&. ‘ I t appears that the greatest majority of the rocks are simplyextrusive rocks. These rocks have subsequently been intruded by a number of nearvertical, sub-pardel dikes which tend to control the internal movement of fluids, especiallyin a direction at right angles to the edge of the rift. Given the lateral partitioning, aquiferand reservoir discontinuities are expected within and between the margins of the rift.DRILLING PERMITS AND INSPECIlONSGeothermal Well Drilling Permits for production wells in Haw& are issued by theDepartment of Land and Natural Resources (DLNR). The Department of Health (DOH)issues an Authority to Construct P d t for both production and injection web, inaddition to a letter of approval to construct dedicated injection wells. In all cases, theoperator submits a proposed drilling program to the respective agencies, which includesinformation the agencies need to show that regulations are and will be met. Included inthe DLNR regulations are a description of casing strings and setting depths, and requiredBlowout Prevention Equipment (BOPE) for various drilling scenarios.5
In w e b KS-7 and KS-8, which were originally proposed as injection wells, the DOHissued the permits to drill, had authority to allow casing changes, but did not have atrained inspector in the field to make drilling observations.On the other hand, an inspector for DLNR typically visited the PGV site daily andrecorded drilling observations, but had no authority to approve changes in operations.At the t h e of the KS-8 incident, DLNR was reviewing a proposal submitted by PGVto complete the well as a production well.GENEWU. DRILLING PROGRAM AT PGV IDCATIONIn the general drilling program, a 26-inch hole is drilled without BOPE from about60' to approximately '1200' and cased. A 17-1/2-hch hole is drilled to (2000