Iwaki Platform was built in 1984, which is located about 40 km off the east coast of Fukushima prefecture, and natural gas has been produced from C-Structure for 15 years. There are a few Satellite fields toward the south-south-west from the platform, which is called C-Satellite North, C-Satellite Central and C-Satellite South and those approximate distances from the platform is 4km, 6km and 7.5km each.
Johban Oki-2 well was drilled to C-Satellite North structure as the first extended reach well in Japan and completed successfully in 1994. After the success of the well, some engineering study mainly regarding rig modification was done for the next ERD to C-Satellite Central structure, however the detail engineering and the execution had been temporarily given up for the various reasons.
From the end of 1998, feasibility study of the ERWs to both C-Satellite Central structure and C-Satellite South structure was conducted as the alternative development instead of subsea completion. The FS covered preliminary drilling engineering, structural analysis of drilling structures and rig modification, and the FS took almost nine months. After all, the execution was totally given up mainly due to the difficulties of the rig modification and reinforcement. This paper reports the critical issues of drilling engineering in this study, 1) well path design, 2) hole cleaning, 3) torque & drag and mud friction, and 4) borehole stability, which will match the subject “The Integration of Technology and Engineering” of the 2000 JAPT Drilling Symposium.
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