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doi:10.2204/iodp.proc.345.108.2014

Hole U1415H¹

K.M. Gillis, J.E. Snow, A. Klaus, G. Guerin, N. Abe, N. Akizawa, G. Ceuleneer, M.J. Cheadle, Á. Adrião, K. Faak, T.J. Falloon, S.A. Friedman, M.M. Godard, Y. Harigane, A.J. Horst, T. Hoshide, B. Ildefonse, M.M. Jean, B.E. John, J.H. Koepke, S. Machi, J. Maeda, N.E. Marks, A.M. McCaig, R. Meyer, A. Morris, T. Nozaka, M. Python, A. Saha, and R.P. Wintsch²

Operations

The location of Integrated Ocean Drilling Program Hole U1415H (see Fig. F8 in the “Expedition 345 summary” chapter [Expedition 345 Scientists, 2014b]) was selected to test sediment thickness and subseafloor drilling conditions, with the aim of finding a suitable site for establishing a deep hole. Hole operations are summarized in Table T1 and outlined below. All times are ship local time (UTC – 7 h).

Near-bottom 3.5 kHz pinger and camera survey

At the end of operations in Hole U1415G and while still at that location, we lowered the camera system with the 3.5 kHz pinger attached and conducted a new survey of the seafloor and near-subbottom (see Table T1 and Fig. F3 in the “Bench site survey” chapter [Expedition 345 Scientists, 2014a]) en route to Hole U1415H, located 20 m west and 15 m south of Hole U1415G.

Drilling operations

After arriving at the coordinates for Hole U1415H, we visually observed the drill bit tag the seafloor at 4857.6 meters below rig floor (mbrf). The camera system was recovered, and Hole U1415H was spudded at 1040 h on 27 December 2012. Rotation began after penetrating ~1.0 m of soft material, and rotary core barrel coring continued to 12.9 meters below seafloor (mbsf). Core 345-U1415H-1R recovered 0.44 m (3% recovery). Drilling conditions in this hole were vastly different than in previous holes. All drilling parameters were much smoother and less erratic; however, when preparing to make a connection, the driller raised the bit off bottom. When the driller attempted to lower the bit back to bottom, immediate formation resistance was encountered. Drilling torque became elevated and erratic, indicating that the hole had once again fallen in. Because it was considered unsafe to attempt making a connection under these circumstances, the decision was made to terminate the hole before possible loss or damage to another bottom-hole assembly. The bit was pulled clear of the seafloor at 0410 h on 28 December, ending Hole U1415H.

¹ Gillis, K.M., Snow, J.E., Klaus, A., Guerin, G., Abe, N., Akizawa, N., Ceuleneer, G., Cheadle, M.J., Adrião, Á., Faak, K., Falloon, T.J., Friedman, S.A., Godard, M.M., Harigane, Y., Horst, A.J., Hoshide, T., Ildefonse, B., Jean, M.M., John, B.E., Koepke, J.H., Machi, S., Maeda, J., Marks, N.E., McCaig, A.M., Meyer, R., Morris, A., Nozaka, T., Python, M., Saha, A., and Wintsch, R.P., 2014. Hole U1415H. In Gillis, K.M., Snow, J.E., Klaus, A., and the Expedition 345 Scientists, Proc. IODP, 345: College Station, TX (Integrated Ocean Drilling Program). doi:10.2204/iodp.proc.345.108.2014

² Expedition 345 Scientists’ addresses.

Publication: 12 February 2014
MS 345-108

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