E.V. Perlova¹, N.A. Makhonina¹, V.S. Yakushev¹, E.M. Chuvilin^2
1Gazprom, VNIIGAZ, Russia , V_Kuzminov@gwise.vniigaz.gazprom.ru
²Dept. of Geocryology, Geological Faculty, Moscow State University, Russia, chuvilin@geol.msu.ru

　　Gas blowouts from permafrost are documented at the very beginning of development of northern gas permafrost. Many of them arise at drilling of a frozen interval and damp quickly enough. Others last for months or renew at the beginning of well operation. For a long time it was considered that gas blowouts are resulted from underlying productive horizons up to the top intervals (on faults, lithological gaps, emergency prospecting wells). Accordingly, intrapermafrost gas accumulations should have local distribution around of these centers of unloading.
　　However at drilling of Yamburgskoe and Bovanenkovo GCF the cases of gas emissions from shallow depths (down to 100-150 m) become frequent [1]. Special detailed researches of a nature and distribution of the intrapermafrost gas accumulations were conducted. That has resulted in new representations about genesis and forms of existing of natural gas in criolithozone.
　　Based on field researches and experimental modeling it can be assumed that at least a part of gas in similar intrapermafrost accumulations exists in a form of clathrate compound - gas hydrate.
　　A number of direct and indirect features point to the gas hydrate form presence. These are high gas saturation of frozen cores, significant wellheads up to 10000 m3/day at high (about 99%) pore filling degree of ice and unfrozen water. Besides a number of the laws connecting gas saturation of frozen soils with their structure and properties indicate the gas hydrate presence [2].
　　All this urges to consider permafrost in a new fashion as a practically unexplored collector of gas and hydrate accumulations.
　　Based on the long-term researches at Yamburgskoe and Bovanenkovo GCF authors offer the system approach to studying of continental hydrate-saturated soils. It includes field and laboratory researches of permafrost cores recovered during drilling, and also experimental modeling of the hydrate existence conditions in disperse soils [3].
References
　　1. Chuvilin E.M., Yakushev V.S., Perlova E.V., Kondakov V.V. Gas component in permafrost of Bovanenkovo GCF (Yamal peninsula). Doklady Akademii Nauk, 1999, v.369, № 4, p. 522 – 524 (in Russian).
　　2. Chuvilin E.M., Yakushev V.S., Perlova E.V. Natural gas and gas hydrate association in permafrost of Yamal peninsula (West Siberia). Proceedings of the 4th International conference on gas hydrates. Yakohama, Japan, 2002, pp. 216-221.
　　3. Chuvilin E.M., Perlova E.V., Dubinyak D.V. Experimental modeling of existence conditions of gas hydrates in marine sediments of Yamal peninsula. Proceedings of the 2th Russian conference of geocryology, Moscow, Russia, 2001, v. 1, pp. 169-173 (in Russian).