抄録
The world's first gas production attempt from a marine methane hydrate deposit is planned in the early 2013 applying depressurization method to a deepwater shallow borehole. The well plan that includes drilling of one production well and multiple monitoring boreholes along with intensive data and sample acquisitions is established to realize scientific objectives and safe operation. The wells are constructed in unconsolidated sediments below 1000m deep water, so then special care is required to assure the zonal isolation during depressurization. The drilling of the holes started in February of 2012, one year advance of the flow test, at the test location in the north slope of Daini Atsumi Knoll in the Eastern Nankai Trough using drilling vessel Chikyu.
The wells were drilled, monitoring systems were installed, and valuable information from geophysical logging and core samples were obtained during the 2012 operation. Detailed plan for the production test will be finalized using data and operational experiences obtained.
