Abstract

Exploratory studies have been carried out to identify the potential natural gas hydrate reserves for commercially producing gas. While extracting the gas from the hydrate-bearing sediments using various dissociation techniques, there will be a significant loss of strength in these sediments. It is well known that the behavior of gas hydrate sediments is governed by Thermo Hydro Mechanical Chemical ­ THMC coupled process during the gas extraction. Thus, in this study, in order to understand the influence of depressurization at the well-bore and the permeability of the hydrate reservoir on the sediment deformation characteristics, a 2D (plane strain condition) hydrate reservoir is simulated (using a multiphase numerical schema). From the study, it is observed that the flow response, i.e., the rate of change of gas pressure near the well-bore, decreases with the increase in the duration of the extraction. The maximum settlement occurs for reservoirs having low well-bore pressure (higher amount of depressurization) and high intrinsic permeability. Additionally, these same reservoir conditions also lead to maximum cumulative gas production. Thus, the continuous gas extraction results in a highly porous medium that is stabilized primarily due to the geomechanical changes.