IODP Expedition 301: The Hydrogeologic Architecture of Basaltic Oceanic Crust: Compartmentalization, Anisotropy, Microbiology, and Crustal-scale Properties on the Eastern Flank of Juan de Fuca Ridge IODP Town Hall Meeting 2004 Fall AGU Meeting San Francisco, CA 14 December 2004 T. Fisher1 and Tetsuro Urabe2 and the IODP Expedition 301 Scientific Party 1 University of California, Santa Cruz 2 University of Tokyo
Expedition 301 Science Party: A. Fisher, T. Urabe, A. Klaus, A. Bartetzko, K. Becker, R. Coggon, M. Dumont, B. Engelen, S. Goto, V. Heuer, S. Hulme, M. Hutnak, F. Inagaki, G. Iturrino, S. Kiyokawa, M. Lever, S. Nakagawa, M. Nielsen, T. Noguchi, W. Sager, M. Sakaguchi, B. Steinsbu, T. Tsuji, C. G. Wheat Additional proponents and collaborators: J. Alt, W. Bach, J. Baross, J. Cowen, S. D’Hondt, E. E. Davis, D. Kadko, M. McCarthy, J. S. McClain, M. J. Mottl, M. Sinha, G. Spinelli, V. Spiess, R. Stephen, D. Teagle, H. Villinger, L. Zühlsdorff
Fundamental questions addressed by IODP Expedition 301 and related experiments • What are the magnitude and nature (distribution, extent of channeling) of permeability in crustal fluid-rock systems, variations, scaling (temporal, spatial)? • What are the magnitudes and directions of driving forces, fluid fluxes, and associated solute and heat transport? • What are the magnitude and nature of storage properties, variations with fluid pressure, scaling (temporal, spatial)? • What are relations between fluid flow, vertical and horizontal compartmentalization, microbiological communities, seismic properties, alteration, structure, and primary crustal lithology? • How large are distinct fluid reservoirs, what are fluid residence times and fluid velocities, and how do these respond to transient processes (tides, seismic events)?
Permeability is at the center of many of these questions… Things we want to understand Things we measure Permeability links observation and process
…and so is the subseafloor biosphere! • What is the diversity, distribution, and size of ecosystems? • What happens when we move from oceanic sediments to basement? • How does microbiology relate to other aspects of water/rock? modified from Parkes et al. (1994), D’Hondt et al. (2003)
Why work on the eastern flank of Juan de Fuca Ridge? • The geology is typical in many ways. • Young crust, thick sediments, create extreme conditions we can measure and sample. • Existing boreholes/CORKs help us understand the system, save time in creating a network of observatories. • Link with future cabled observatory system: NEPTUNE. Eventually, we will need to test several areas, but this is the best place to start.
Expedition 301 and follow-up expeditions will provide many new opportunities and results… • First controlled, cross-hole seafloor experiment; • First multi-directional hydrogeologic experiment (both vertical and multi-azimuth); • First active large-scale assessment of storage properties and effective porosity; • First combined (simultaneous, co-located) hydrogeologic, microbiological, tracer, seismic experiment; • First long-term active experiment (hours to multi-year); • First attempt to measure multiple scales (temporal, spatial) with the same techniques, link to primary lithology, alteration, etc.
Summary of IODP 301 Operational Plans • Create/modify a network of boreholes (two existing, two new), penetrating up to ~300-400 m of permeable basement; • Conduct wireline logging, VSP, short-term packer tests; • Install long-term observatories (CORKs) to monitor pressure, temperature, collect fluid samples, colonize microbes; and • Collect sediment and rock samples and evaluate lithology, alteration, microbiology, fluid chemistry. • Prepare for installation of additional holes to conduct cross-hole hydrogeologic, microbiological, geochemical, and seismic experiments at a range of spatial and temporal scales (meters to kilometers, minutes to years) in the same holes.
IODP 301 site locations… Second Ridge area Second Ridge (SR): Primary Sites First Ridge (FR), Deep Ridge (DR): Secondary Sites
Planned SR operations • Replace CORKs at 1026B (higher priority), 1027C (lower priority) • Drill holes at Site 1301, ≤400 m into basement, core, log, BHTV, VSP, packer, CORK multiple intervals, additional sediment coring • Drill Hole SR-2A, ≤200 m into basement, core, sample, log, BHTV, VSP (offset), packer, CORK multiple intervals • Long-term testing (1-3 years) within and between holes
Simultaneous and Co-located Hydrogeologic, Microbiological, Seismic, Tracer Experiments (1) Hydrogeologic Experiments: • Single-hole tests • Use CORK’ed wells as observation points, pump across wells • Pump for 24 hours, let equilibrate for 6-12 months, open valve(s) to overpressured interval(s), allow to flow for 12-24 months = "artesian well" test • Test multiple scales, directional properties, differences in properties and relations
Simultaneous and Co-located Hydrogeologic, Microbiological, Seismic, Tracer Experiments (2) Microbiological Experiments: • Which microbes live where, how? • Three main stages of analysis: (a) Sediment coring, sampling (b) Basement coring, sampling (c) Long-term fluid sampling, incubation • Long-term samplers and colonization substrate deployed within sealed boreholes • Vent overpressured system at seafloor, time-series sampling, additional seafloor experiments
Simultaneous and Co-located Hydrogeologic, Microbiological, Seismic, Tracer Experiments (3) Seismic Experiments: • Collect wireline logs in deep basement holes • Single-hole VSP in Holes 1301B and SR-2A • Offset VSP, shoot from another ship to the hole • Determine directional basement seismic properties, relations to hydrogeologic and other properties
Simultaneous and Co-located Hydrogeologic, Microbiological, Seismic, Tracer Experiments (4) Tracer Experiments: • Thermal, modeling, and geochemical studies suggest fluid velocities on the order of kilometers per year • Pump multiple tracers in multiple holes and depths during hydrogeologic tests • Monitor individual holes and depths for tracer return patterns (single-hole tests) • Monitor for across-hole tracer appearance, also monitor natural discharge on Baby Bare outcrop
Expedition 301 CORK system features • In new holes: four nested casing strings (three to hold open hole, one for CORK) • Multiple sealing systems: cement, packer(s), CORK body, CORK casing (top and bottom) • Tubing extends to depth for fluid and microbio sampling, pressure monitoring, several kinds of umbilicals used • Autonomous temperature loggers, OsmoSamplers, microbio cells within/below CORK, hung on Spectra cable • Pressure logger attached to CORK head by ROV/sub after CORK deployment • System allows monitoring of formation and cased intervals, to evaluate CORK performance
Hoisting CORK onto rig floor Sampling/ monitoring bay Top seal
Raising CORK in the rig in preparation for deployment through the moon pool
Attaching umbilicals to pass-throughs on main CORK seal Hero Hero Hero Hero
Autonomous temperature loggers, attached to downhole instrumentation and cables
Three bays on CORK head for uphole instrumentation and access to samples
Extensive microbiological sampling and analysis (9% of basement rock, much of the sediment)
Post-IODP 301 operations • E. Davis (PGC) and R. Dixon (US-IO) returned to Exp. 301 CORKs on R/V Thomas G. Thompson in September 2004 • Installed pressure loggers, closed valves • Recovered some OsmoSamplers from CORK heads • Inspected CORK installations
Expedition 301 achieved critical objectives • Successes are remarkable considering limited time available to prepare… • Now poised to finish drilling and related work, conduct long-term, active tests in the crust… • Appropriate for the first expedition of IODP - a new kind of experiment