Comparison of the Vertical Gas-Hydrate Production Profile with the Simulation Results Obtained Using Geophysical Log-Based Reservoir Characteristics and Reasons for Their Discrepancies in the Nankai Trough

In this study, we analyzed the temperature and pressure measurement data obtained from the production test of methane hydrates in the second offshore production wells of Nankai Trough (2017). Based on the analysis, we derived time-series information on the vertical profile and the gas and water influxes in the wells via an optimization process. The time-series information revealed variations in the vertical production profiles and behavior between two production wells. Some discrepancies were observed in the petrophysical characteristics, particularly in the permeability between the wells, while comparing the measurement-based profile and simulation results based on geophysical log-based reservoir models. The discrepancies are attributed to the water-producing layers and some near-wellbore phenomena, which also inhibit stable and increasing gas production in the well. Current studies on gas hydrate by the Japanese national gas-hydrate resource development project focus on identifying the causes of these problems and possible countermeasures.

Automated summary

The study analyzed temperature and pressure data from the production test of methane hydrates in the Nankai Trough, revealing variations in vertical profiles and behavior between two production wells. Discrepancies in petrophysical characteristics, especially permeability, were observed between the wells, likely due to water-producing layers and near-wellbore phenomena. Research is focused on identifying the causes of these issues and potential solutions.