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doi:10.2204/iodp.proc.345.112.2014

Hole U1415O¹

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 only operations in Integrated Ocean Drilling Program Hole U1415O consisted of drilling a 14¾ inch hole to 17.0 mbsf. After reaching this depth, we prepared to establish reentry capability but had to abandon the hole because of poor hole conditions. The location of Hole U1415O is shown in Figure F8 in the “Expedition 345 summary” chapter (Gillis et al., 2014b), and operations in this hole are summarized in Table T1 and outlined below. All times are ship local time (UTC – 7 h).

Drilling operations

Following unsuccessful operations in Holes U1415K–U1415N on the shoulder, we decided to move back to the bench. The bottom-hole assembly (BHA) was changed to a drilling assembly with a 14.75 inch tri-cone bit and lowered to the seafloor. While the BHA was being deployed, a new free-fall funnel (FFF) cone was prepared for deployment. We deployed the camera system with the 3.5 kHz pinger attached and conducted a seafloor survey around the target drilling location (see Table T1 and Fig. F3 in the “Bench site survey” chapter [Gillis et al., 2014a]). We also observed the bit tag the seafloor at 4861.0 meters below rig floor). The survey was completed at 1536 h on 25 January 2013, and the camera system was back on board at 1815 h. Drilling in Hole U1415O started at 1900 h. The bit was washed down 1.5 meters below seafloor (mbsf) and then drilled in a massive, hard formation to 5 mbsf. At 5 mbsf, the bit penetrated 10 m (to 15 mbsf) in only 15 min. The formation firmed up from 15.0 to 17.0 mbsf by 0345 h on 26 January. We then successfully conducted a wiper trip and prepared to deploy the FFF cone. At this time, the hole began to collapse, and our attempts to drill and ream back to bottom failed; we could only get back to ~8 mbsf. We decided to abandon Hole U1415O at 0700 h on 26 January. The bit cleared the seafloor at 0710 h, ending Hole U1415O.

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 U1415O. 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.345.112.2014

² Expedition 345 Scientists’ addresses.

Publication: 12 February 2014
MS 345-112

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