METHOD OF WELL EQUIPMENT EXTRACTION Russian patent published in 2020 - IPC E21B31/00 E21B37/06 

FIELD: oil, gas and coke-chemical industries.

SUBSTANCE: invention relates to oil and gas industry, namely to methods of well cleaning from deposits, including chemical reagents, for extraction of downhole equipment. Method includes, prior to extraction of equipment, pumping into well with pumping unit of flushing liquid, which represents fresh water with density, lower density of formation water through annular space to downhole equipment and back through the pipe string to the surface. Preliminary determined minimum and maximum allowable pressure for penetrated formation to prevent its integrity violation. Prior to pumping flushing fluid through annular space by pumping gas with well pump, reducing level of well fluid is not less than minimum allowable pressure on formation. Fresh water is pumped with maximum possible pressure for formation with provision of intensive turbulent flow for cavitation effect on deposits, if necessary, treatment is repeated. In the presence of a large amount of precipitation in the well, the composition of the precipitate is pre-determined, based on which the type of reagent, its volume and reaction time for dissolving the sediment are determined. After pumping of turbulent flow, but before extracting well equipment, selected reagent is injected into annular space with density below density of formation water and left for reaction time with operating or idle equipment.

EFFECT: simplified technology, increased efficiency of reagents usage.

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