FLUSHING METHOD OF SAND PLUG IN GAS WELL IN CONDITIONS OF ABNORMALLY LOW FORMATION PRESSURES Russian patent published in 2012 - IPC E21B37/00 

FIELD: oil and gas industry.

SUBSTANCE: during implementation of the method the low pressure gas is supplied from production well to booster compression station, compressed and supplied to gas processing facility (GPF), where gas is cleaned from mechanical impurities and water and supplied to booster station to which service water is pumped by means of pump unit. The obtained gas-liquid mixture is compressed. Mixture is separated in separator; liquid is supplied again to pump unit and gas is supplied to ejector inlet. Foam-forming liquid is supplied to ejector mixing chamber. The obtained aerated foam-forming liquid is supplied to flexible pipe (FP) of coil tubing unit and FP is lowered to tubing string till it touches sand plug head. At that, gas is directly supplied to annular space with GPF and plug destruction is started with aerated foam-forming liquid and gas supplied from annular space. Flushing is performed in stages. FP is deepened step by step into the plug body to the depth of 3-4 m; then, lowering is interrupted, FP is slightly raised to the height of 1-2 m, and supply of foam-forming liquid to ejector is stopped. The gas supplied to FP bypasses the ejector, and gas with GPF is supplied to annular space and aerated foam-forming liquid is blown with particles of destructed plug out of the well. Gas supply is continued till clean gas is obtained on the head. Then, sand plug destruction and removal operations are repeated.

EFFECT: improving plug removal reliability.

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