Thermodynamic State of Gas Hydrate in the Krishna-Godavari Basin Inferred From Well Log Analysis

摘要

We examined the in-situ hydrate saturations and salinities of gas hydrate-bearing sediments at NationalGas Hydrates Project (NGHP) Site 01-10A in the Krishna-Godavari Basin, offshore India, to determinethe thermodynamic state of the hydrate system. We determined hydrate saturations using logging-whiledrilling(LWD) data in an iterative application of Archie’s Law. The in-situ salinities were calculated fromcore-derived salinities by assuming that salts remained in the pore space, that the hydrate dissociatedcompletely, and that pore volume remained constant with hydrate formation and dissociation. The in- situsalinity was compared to that required for three-phase equilibrium. We interpret two regions between 45- 90 and 123 - 160 meters below seafloor (mbsf) where the system is at three-phase equilibrium at Site01-10A.