PROCEDURE FOR PREVENTION OF WELLHEAD FREEZING IN PRESSURE WELL Russian patent published in 2011 - IPC E21B36/00 

FIELD: oil and gas production.

SUBSTANCE: here is disclosed procedure for prevention of wellhead freezing in pressure well. The pressure well is equipped with a production string (PS). The PS is communicated with an above-ground water conduit to pump fluid via shut-off accessories and to drain fluid from the water conduit into the well when pumping is terminated. The procedure consists in pumping fluid through shut-off accessories corresponding to a spring-loaded valve under pressure exceeding force, opening the spring-loaded valve through an above-ground part of the water conduit. From the side of the well this part is equipped with a pipeline at the spring-loaded valve, and it is equipped with a float valve on the other side from the valve in an upper point. Also, fluid is drained in the PS from the under-ground part of the water conduit below the level of seasonal frost penetration into ground via the pipeline on above-ground part of the water conduit after float valve opens at excess of pressure drop between the water conduit and environment. This pressure drop is created with fluid flowing into a reservoir, when well stops, and it holds the float valve.

EFFECT: reliable prevention of wellhead freezing at durable stops of well operation; reduced material and labour expenditures at implementation of this procedure.

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