One of the major characteristics of the Chikyu is the riser-drilling system. The blow-out-preventer (BOP) plays an important functional role in the riser-drilling operation, which has functions that controls the pump pressure of circulation drilling mud, monitors/controls the borehole pressure, and prevents the potential explosion of deep natural gas or fluids. The weight of BOP is approximately 380 tons and the height is 14.5 meter (see the photo). The BOP is connected with the multiple riser pipes, which is also very large; a riser pipe is 27 meters in length and 50 cm in diameter. The riser pipe will be connected each one by one on the drill floor, landing the BOP on the well head at 1180 meters in water depth. If we set up the all BOP and riser pipes down to our target water depth, the total weight will be over 1000 tons!! Chikyu is big enough and enables to do it.

The blow-out-preventer (BOP) for the riser drilling is ready to go down from the moon pool on the Chikyu to the deep seabed.

After the departure from the port of Hachinohe, the drilling team on the Chikyu has been working very hard for the preparation of the BOP installation and running, for which all the safety and regulation tests such as pressure and control function are carried out on the ship. The preparation is crucial for all the planned operations. Because it is difficult to be done in the deep-sea, it needs to be completely done on the ship before we start drilling. Today, we have finally completed the preparations and pressure test and now I see the BOP connected to the bottom riser pipe is placed in the moon pool :-)

Due to the preparation, the current status is approximately 6 days-behind of the original operational plan. However, we will modify the drilling program by directly using 17-1/2 inch drill bit instead of 10-5/8 inch bit (see: operation sequences at http://www.jamstec.go.jp/chikyu/exp337/e/schedule.html), which will make the drilling speed much faster and recover several days.

See Exp. 337 operation sequences

Shipboard scientists are now almost ready and very much looking forward to having the samples on board. During the initial phase of drilling down to 1225 meter in depth, on-line/on-time geochemical analyses of the circulating mud-gas (natural gas) in the newly developed mud-gas geochemistry lab, as well as sedimentological, fossil-based paleontological, (bio-) geochemical and microbiological analyses of the drilling fluids and cuttings during the riser drilling, will be carried out. Most of these related to the riser drilling are in fact the first attempt in the scientific ocean drilling that has a half-century of the history.