Implementation of a Fit-for-Purpose Cementing Technology for the First Gas Hydrate Production in Japan

Abstract

Abstract JOGMEC (Japan Oil, Gas and Metals National Corporation) was planning for the first offshore production test of methane hydrates in the eastern Nankai Trough off of Japan. The test needs one production well and three temperature monitoring wells to study the dissociation performance of methane hydrate formations. Cementing these types of wells needed to have a specific cementing technology fit for deepwater shallow unconsolidated formations subject to subsidence and methane hydrate-bearing formations. A project was initiated in 2011 with the objective being to design and qualify a cement slurry system fit for deepwater shallow unconsolidated formations subject to subsidence and methane hydrate-bearing formations. Based on extensive laboratory and full-scale testing, a cement technology was qualified by the service company and approved by JOGMEC to be the optimum solution for this unique project. This paper will describe the full-scale and extensive laboratory testing used to qualify the cement technology fit for this application and the different stages that create sufficient wellbore stability for the drawdown during the production test. In addition, real-time temperature data interpretation will be presented showing the cement hydration in these wells after placement. Case histories of the three wells will be presented. Introduction One of JOGMEC's corporate objectives is to overcome the constraints resulting from limited resources by investigating the next-generation energy resources, which includes research on methane hydrates. Methane hydrates (MH) available within Japan's territorial waters may well be able to supply Japan with its natural gas needs. Deposits of methane hydrates have been reported in marine sediments of the Nankai Trough off the Pacific coast of central Japan, where the water depth is more than 500 m (Fig. 1). Some estimates indicate that the methane hydrate reserves correspond to a 100-yr supply of natural gas for Japan, making it an important potential energy source. The Japan National Oil Corporation (JNOC) began research work on methane hydrates in 1995, and JOGMEC has overseen the project since the restructuring of JNOC. The 16-yr exploitation project extending from 2001 to 2016 is being led by METI (Ministry of Economy, Trade and Industry) as one of the Japan national projects. The three-phase project consists of the following steps:· Phase 1—2001–2008– Perform fundamental R&D for exploration, basic properties, and laboratory investigation– Select MH resource fields and assess the amount– Verify production methods through onshore testing· Phase 2—2009–2015– Perform fundamental R&D for production and environmental impact assessment– Verify production methods through offshore testing