Forecast of Distribution and Thickness of Gas Hydrate Stability Zone at the Bottom of the Caspian Sea

Abstract

The Caspian Sea is a region of active hydrocarbon production, where apart from conventional accumulations, gas hydrates (GH) are known to exist. GH are a potential future source of energy, however, currently they pose danger for development of conventional fields. The goal of this research was to determine the area of GH distribution and thickness of their stability zone in the Caspian Sea using numerical modeling and to define how certain parameters affect the calculated thickness. As a result of the research, cartographic schemes were created for the South and Middle Caspian, where GH were predicted. For the South Caspian, conditions for methane hydrates formation exist at depths of more than 419–454 m, and for the Middle Caspian, more than 416–453 m. The maximal thicknesses of methane hydrates stability zones for the South Caspian can reach 900–956 m, and for the Middle Caspian, 226–676 m. Variations of parameters of seafloor depth, geothermal gradient and gas composition can significantly change the resulting thickness of GH stability zone.