WELL SWABBING METHOD Russian patent published in 2011 - IPC E21B43/18 

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil industry and can be used during well swabbing. Essence of invention: during well swabbing the separation of tube space is performed above production horizon at the level of 5-20 m and back-and-forth movement of swab is performed in tubing string with extraction of well fluid to the well head. Swab is lowered along tubing string and arranged below the fluid level to the value determined with value of critical pressure drop during swabbing to cement column in the section of impermeable rock separating productive formation and water-bearing formation. Value of maximum allowable depression per formation is determined as per analytical equation considering the value of maximum allowable depression per formation, height of cement attachment between water-bearing or watered formation developed and non-opened with perforation, which is determined as sum of intervals only with satisfactory adhesion to rock and string, pressure in productive formation and in water-bearing or watered formation non-opened with perforation, which is the closest to the developed productive formation.

EFFECT: providing elimination of water inflow at swabbing owing to preventing critical drop of pressure on cement column in annular space of the well and limitation of value of maximum depression at swabbing depending on height of cement column and pressure in water-bearing or watered formation.

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