Feyzullayev, Akper A.¹, Chingiz S. Muradov¹
(1) Geology Institute of Academy of Sciences, Baku, Azerbaijan

ABSTRACT: Gas Hydrates in Submarine Mud Volcanoes, the Southern Caspian Sea

Gas hydrate accumulation, associated with active submarine mud volcano (MV), was discovered first time in the Southern Caspian Sea (SCS). Gas is thermogenic, coming along volcanic channel towards seabed from deep-sited reservoir. There are over 160 MV in SCS, about 60 of which are located in deep waters; all of them may be hydrate bearing. In contrast to land MV they escape the gas into the sea water. Under marine conditions the part of this hydrocarbon gases is converted into hydrate and is retained. Content of gas in hydrate on one MV is about 3x108m3. The abundance of biogenic hydrates should be also significant in SCS, but such type of gas hydrate is not discovered yet here. The water depths in SCS increase sharply from 50 to 1000m. Deep-water temperature is about 5-60C. Therefore, large of sea area has necessary thermobaric conditions for gas hydrate formation in sediments. Depend upon temperature-pressure conditions and gas composition hydrate could be formed in SCS in water depths more than 100-400m. Gas hydrate is stupendous object not only as future energy recourses, but also as potential hazards for offshore exploration activities. Presence of gas hydrates in crater of submarine mud volcanoes enhances the chances of offshore explosive eruptions, because gas hydrate cover plays a role of seal, which hampers the discharge of volcanic gas and hastens accumulation of explosive energy. Average value of gas flux from one onshore MV is up to 1,7x104m3/year.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.