METHOD FOR EXTRACTION OF CONVENTIONAL AND HYDRATED GAS OF MULTI-FORMATION DEPOSIT AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2024 - IPC E21B43/295 E21B23/00 E21B33/122 

FIELD: mining.

SUBSTANCE: invention relates to a method for extraction of conventional and hydrated gas from a multi-formation deposit and a device for its implementation. Method includes extraction of well product of multi-formation deposit, which is carried out in stages depending on ratio of formation pressures of conventional and hydrated gas. At the initial stage of deposit development, when P_form.c > P_form.h, where P_form.c is formation pressure of underlying formation of conventional gas, P_form.h is formation pressure of overlying hydrate formation; reduction of bottomhole pressure for hydrate formation, its dissociation and extraction of hydrate gas is performed due to pressure drop of gushing conventional gas on pulse ejector introduced into production equipment. At the final stage of the deposit development, when P_form.h > P_form.c, low-pressure gas (LPG) is extracted due to pressure of hydrate gas formed as a result of natural or artificial decomposition of gas hydrate remaining in the formation. During extraction of well product through perforation channels, depressions and repressions are cyclically applied to hydrate formation and due to redistribution of stresses in its depth zones of induced fracturing are created. In cycles of depressions and repressions, a wave mode of pressure variation in perforated channels is used. Drilling of the hydrate formation with perforation channels is carried out at the distance of not closer than 2÷4 m around the main shaft by two branched groups at location of group joints with the main shaft at different levels in the roof of the hydrate formation. First group of perforation channels is drilled with a dead end in the hydrate formation without entry into the underlying formation of conventional gas. Second group – through the entire hydrated formation with entry into the formation of conventional gas. Extraction of well products is also carried out in wave mode. At the initial stage of deposit development the first group of perforation channels is connected to a pulse ejector, which is supplied with conventional gas as an active agent. Separated hydrated gas of the hydrate formation is used as a passive agent. Portion of the conventional gas is extracted through the annular space, the second group of perforation channels and the hydrate formation with the possibility of thermal action on it. At the final stage of the field development, when extracting low-pressure gas LPG, the first and second groups of perforation channels are used simultaneously for additional mechanical, chemical and (or) thermal action on hydrate formation and conventional gas formation through them in wave mode.

EFFECT: intensification of action on deposit, increase of formation coverage and increase of well product flow rate at reduction of capital, operational and energy costs and accident rate of works.

2 cl, 3 dwg