Research on the development of the Nankai gas hydrates field

Abstract

The analysis of the development of the world’s first shelf field of methane hydrates on the east coast of Japan was carried out. To develop the marine Nankai gas hydrate deposit, a highly concentrated hydrate deposit discovered in turbidite sediments in the Nankai East Trough area, seismic exploration and exploratory drilling were performed. After intensive study of core samples and geophysical logging data obtained in previous studies, as well as additional engineering and geological studies, a development site was selected on the northern slope of Daini Atsumi Knoll. There were a number of goals: 1) to determine the production rate in a short period (from one to several weeks), 2) to achieve stability, integrity of wells drilled in loose sediments, 3) to implement monitoring technology to collect information on the state of methane hydrate during development. During the experimental work on the development of the gas hydrate deposit, the deep-water drilling vessel Chikyu was used. The water management system on the ship processed water from the reservoir, the degasser had removed dissolved methane, which was burned in the installed burner on the stern of the ship. Filters with gravel packing reduced the concentration of suspended particles associated with sand ingress when affected by a productive formation. The results of the 6-day stable development proved that the dissociation of methane hydrate is possible in marine sediments.