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Site 10261

Expedition 301 Scientists2

Site summary

Three Circulation Obviation Retrofit Kit (CORK) borehole observatories were installed during Expedition 301 in Holes 1026B, U1301A, and U1301B. The first of these systems replaced a CORK observatory deployed during an earlier expedition; the second and third are in newly drilled and cased holes. The new Hole 1026B CORK system was the simplest of the systems deployed during Expedition 301. It comprised a CORK-II body with 4½ inch casing extending to 201.5 meters below seafloor (mbsf) and a single packer element set in casing near the bottom of the 4½ inch casing. No 4½ inch casing was installed below the packer element sub because the hole was completely cased at depth, and there was no need to provide additional protection for the instruments hanging below the bottom plug.

The umbilical run in Hole 1026B comprised a single ½ inch packer inflation line and three ¼ inch pressure-monitoring and fluid-sampling lines. The three ¼ inch lines were run through the single packer and ended in small wire-wrapped screens that were attached just below the inflation element. All of the CORK systems deployed during Expedition 301 included nine pass-throughs within the packers and across the upper 10¾ inch casing seal so that we could use a single design for these systems and achieve sampling and monitoring goals within multi-interval CORKs. Most of the extra pass-throughs in the Hole 1026B CORK were capped, but one line through the 10¾ inch casing seal was plumbed into a two-way valve in the CORK head so that during a future submersible or remotely operated vehicle (ROV) dive expedition it will be possible to check pressure below the casing seal but above the packer element. If the pressure monitored below the packer is different from that above the packer, this will give a positive indication that the CORK system is properly sealed. As with all other valves in the CORK head, this one was left open during deployment to prevent air from being trapped in the sampling and monitoring lines.

The Hole 1026B instrument string included three OsmoSampler packages and two autonomous temperature loggers. One OsmoSampler contains copper coils for gas sampling, another has polytetrafluoroethylene (PTFE) tubing for fluid sampling and tracer injection, and the third contains microbiological growth substrate and an acid-addition OsmoSampler for metals analyses.

1Expedition 301 Scientists, 2005. Site 1026B. In Fisher, A.T., Urabe, T., Klaus, A., and the Expedition 301 Scientists, Proc. IODP, 301: College Station TX (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.301.107.2005

2Expedition 301 Scientists’ addresses.

Publication: 31 October 2005
MS 301-107

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