Construction of 3 dimensional methane hydrate reservoir model in Eastern Nankai Trough and prediction of production test performance

MH 21 Research Consortium in Japan is planning to implement a gas production test targeting a methane hydrate (MH) reservoir located in MH concentrated zone in the Eastern Nankai Trough (ENT). Two areas surrounding the exploration wells drilled in different MH concentrated zones in ENT were selected as candidates of the production test area because of the availability of well log analysis and seismic interpretation results. The evaluation studies for these areas have been conducted from the various points of view to implement the test successfully. As one of these studies we constructed the 3D reservoir models for the areas consulting the well log analysis and the seismic interpretation results, and predicted the production test performances through numerical simulation. This paper shows how we constructed the 3D models and what results we obtained thorough numerical simulation.First, the frames of the 3D reservoir models for the vicinity of the candidate wells were constructed by consulting seismic interpretation results. The flames were then divided into multiple layers to reproduce the alternating beds structure of sand and mud reflecting the well log interpretation results. The distributions of reservoir properties of each grid layer were estimated by geostatistical techniques using well log interpretation results as hard data and seismic attributes as soft data. Finally the reservoir models were completed by specifying initial pressure and temperature.The well production test performances were predicted through numerical simulation assuming the application of depressurization method. In addition, case studies were conducted to investigate the effect of various scale heterogeneities on the production test performances. The followings were reveled through these studies :(1) Average gas production rate during 30 day test would be over 50,000 m3/d.(2) Large scale heterogeneities such as faults and reservoir dip would affect production test performances significantly.