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doi:10.2204/iodp.proc.345.106.2014

Holes U1415D and U1415E¹

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 locations of Integrated Ocean Drilling Program Holes U1415D and U1415E (see Fig. F8 in the “Expedition 345 summary” chapter [Gillis et al., 2014b]) were 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

Following the completion of operations in Hole U1415C and while still at that location, we assembled a new bottom-hole assembly (BHA) and lowered the bit to just above the seafloor. We lowered the camera system with the 3.5 kHz pinger attached and initiated a new survey of the seafloor and near-subbottom (see Table T1 and Fig. F3 in the “Bench site survey” chapter [Gillis et al., 2014a]). The 3.5 kHz pinger ceased transmitting ~100 m into the survey, and we shortened the survey, which was completed using only visual observations of the seafloor.

Hole U1415D drilling operations

A new location to drill was selected, and the ship moved into position for Hole U1415D. Following a routine slip and cut of the drill line, we observed the bit tag seafloor at 4850.8 meters below rig floor (mbrf). Hole U1415D was spudded at 2355 h on 24 December 2012. We conducted a jet-in test that advanced 4.2 m into the seafloor. The bit was pulled clear of the seafloor at 0026 h on 25 December, ending Hole U1415D.

Hole U1415E drilling operations

After the camera system was recovered, we installed a fresh core barrel and spudded Hole U1415E at 0330 h on 25 December 2012. This hole was rotary cored from seafloor (4850.8 mbrf) to 22.2 meters below seafloor (mbsf) (4873.0 mbrf). Cores 345-U1415E-1R and 2R were recovered (0–15.3 mbsf) with 5% recovery. Very difficult hole conditions were encountered throughout the interval, with high pump pressure, high drilling torque, and hole collapse occurring every time the bit was picked up off bottom. While cutting Core 3R (15.3–22.2 mbsf), the pump pressure dropped from 800 to 350 psi at 70 strokes/min, top drive torque dropped off significantly, and the driller noticed a string weight loss of ~10,000 lb, indicating a likely BHA failure. The drill string was recovered, and the fourth drill collar pin (first collar above the outer core barrel stand) had broken off. Besides the inner core barrel assembly, three drill collars and the entire outer core barrel assembly were lost in the hole. In addition, two other drill collars were bent. Only the uppermost stand of drill collars was in working condition.

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. Holes U1415D and U1415E. 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.345.106.2014

² Expedition 345 Scientists’ addresses.

Publication: 12 February 2014
MS 345-106

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