WELLHEAD CHECK VALVE FOR OIL, OIL-AND-GAS WELLS Russian patent published in 2009 - IPC E21B34/02 E21B33/03 

FIELD: oil-and-gas production.

SUBSTANCE: invention relates to oil and gas industry, particularly to devices which provide for uninterrupted operation of oil or oil-and-gas wells, characterised by annular gas show. The wellhead check valve comprises a hollow body, fitted with a supply pipe for the main component - formation fluid, mainly oil, and a supply pipe for the released component, mainly annular gas, as well as a supply pipe for the mixture of the main and released components. An internal unit is mounted inside the housing of the check valve, with a cup-shaped body, which has one channel in its side wall for releasing annular gas. The check valve also includes a shutting-off device inside the cup, with movable and immovable parts and dividing its cavity into an inlet part in front of the shutting-off device and a working part behind the shutting-off device in the direction of flow of the annular gas, linked to the stream of formation fluid through a channel in the side wall of the cup. The shutting-off device is mounted in the cup and its immovable part rests on the side wall of the cup of the internal unit of the check valve.

EFFECT: provision for uninterrupted operation of the well due to the check valve, which can wash the cup of the internal unit of the check valve with warm formation fluid, virtually on the entire perimeter during the entire operation period, as well as provision for an optimum thermal mode for any unfavourable external conditions.

20 cl, 11 dwg