To execute an excavation work continuously, by drilling the bottom of the sea by an excavating assembly while hanging a coiled tubing and laying it in the drilled well.
An excavating assembly 5 is arranged at the front end of a flexible coiled tubing 2. A downhole motor and a bit are attached to the excavating assembly through a separation device. The coiled tubing 2 is separably set to the excavating assembly 5 with the separation device. The coiled tubing 2 is paid out into the sea in the state the excavating assembly is suspended to excavate the bottom 9 of the sea by the excavating assembly and form a hole 10 in which the coiled tubing 2 is laid, in the bottom of the sea. In this way, the drilling machine is not influenced by the variation of position of the boat and the vertical movement of the boat resulting from waves, by use of the flexible coiled tubing 2.
OBARA SHOZO
SEKINO HIROYUKI
BOSAI KAGAKU GIJUTSU KENKYUSHO