Depressurization in a pioneering test flow of methane from hydrates offshore Japan earlier this year involved a specially designed electric submersible pump system able to separate methane from water and move them to the drillship through separate production strings (OGJ Online, Mar. 12, 2013).
Baker Hughes Inc. designed the completion system under contract to Japan Drilling Co. Ltd., which is working for Research Consortium for Methane Hydrate Resources in Japan.
Japan Oil, Gas & Metals National Corp., the well operator, reported the noncommercial flow of methane from hydrates from a well drilled to 300 m below the mud line in 1,000 m of water in the Nankai Trough about 60 km off southeastern Japan.
Baker Hughes conducted an engineering study to design a completion system that would lower pressure in the reservoir enough to break down the hydrate to methane and water, control sand during production, and acquire large amounts of downhole data for use in reservoir modeling.
The company provided a system that included 0º C. qualification testing of standard products, a gravel-packed lower completion, the ESP system, a custom-designed dual-string production packer, real-time electronic pressure-temperature and memory gauges, and a distributed temperature-sensing fiber-optic monitoring system.
Baker Hughes said the research consortium estimates methane hydrate formations in the eastern Nankai Trough hold as much as 40 tcf of methane in place.