ABSTRACT:

Methane Hydrate (MH) is considered to be one of the new-generation energy resources. For the development of production method to extract the methane gas from MH sediment, it is important to estimate the sediment deformation. In order to understand the geo-mechanical behavior of MH sediment, laboratory experiment (consolidation test) has been performed in the National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba in Japan. Gas and water production, temperature and displacement of artificial MH sediments were measured in this test. Also, Geo-mechanical simulation code ‘Coupled thermo-hydro-mechanical analysis with dissociation and formation of methane hydrate in deformation of multiphase porous media (COTHMA)’ were developed to predict the sediment deformation during the methane gas production from MH sediment. In this code, multi-phase flow consisting of methane gas and water and deformation of MH sediments during MH dissociation are calculated by finite element method. We simulated the laboratory experiment by using ‘COTHMA’. We obtained the good history matching results between the measured and calculated data. In addition, we carried out the field scale simulation for the methane gas production from MH sediment. In this presentation, we will talk about the outline of ‘COTHMA’.

INTRODUCTION

Research Consortium for Methane Hydrate Resources in Japan (MH21) have developed the efficient and economical production method of methane gas from methane hydrate sediments. For development of production method, ‘evaluation technology for sediment characteristics’ is very important to evaluate the long-term safety for the sediment deformation and consolidation behavior of sediment during gas production from an MH reservoir. Development of the evaluation technology for sediment characteristics consists of 1) Development of a geo-mechanical simulation code, 2) Well integrity, 3) Evaluation method for wide area sediment deformation. We have developed the geo-mechanical simulation code for the evaluation technology for sediment characteristics.

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