The paper considers the possibility of the formation of technogenic gas deposits under the permafrost-hydrate seal. As the most promising object, the upper part of the Mastakh gas condensate field section is justified and considered. By comparing the equilibrium conditions of hydrate formation with the pressure and temperature of the formation, the lower boundary of the permafrost-hydrate seal was determined, which forms a potential trap for the accumulation of gases due to their flows through the well space from deeper horizons of the field section. Based on the results of the conducted studies, maps of the sole of permafrost rocks and the sole of the hydrate formation zone were constructed. The potential volumes of flow gases from the Lower Jurassic deposit to the upper part of the section have been estimated. The necessity of additional study of the upper part of the Khapchagai mega-shaft section is noted both for the search for technogenic gas deposits and for preventing complications and accidents associated with technogenic deposits. Keywords: Khapchagai megashaft of the Vilyui syneclise; behind-thecasing flows; Mastakhskoye field; permafrosthydrate seal; oil and gas potential.