Deepwater Methane Hydrate Gravel Packing Completion Results and Challenges

Abstract

Abstract The world's first subsea gravel packing for methane hydrate was conducted and production test successfully executed in the eastern Nankai Trough area off the coast of central Japan in March 2013. Methane hydrate formations all over the world promise huge energy reserves on the earth to permafrost zones in the Polar Regions, and formations within several hundred meters from the seafloor of an ocean. The formation and shallow depths create an assortment of issues that must be addressed to successfully produce this resource. The gas production from methane hydrate formation is different from conventional oil and gas formations in terms of the mechanism and the phenomena, since low temperatures, high pressures environment, and physical properties change in the formation as methane hydrate dissociation. It is important to overcome the above issues for methane hydrate production. During the planning process, studies were completed to review the formation particle size, the low-temperature effects on tools, circulating temperature issues, the erosional considerations and potential subsidence of the formation. Various experienced processes were used and testing completed to prove the integrity of the system that utilized several nonstandard pieces of equipment and procedures. Vigorous preplanning, experienced personnel and onsite expertise enabled the people and equipment to be prepared for the procedure allowing successful variations. Post-job analysis and review of how the various products and services worked together will enable further success in the future. This paper discusses the application of vertical open hole gravel packing in a methane hydrate production well from a floating-rig environment in the eastern Nankai Trough area off the coast of central Japan. It reviews the pre-planning process, the equipment selection, procedure recommendations and the on-job decision-making that enabled the successful flow testing.