METHOD FOR MECHANICAL CLEANING OF WELL STRING WALLS Russian patent published in 2020 - IPC E21B37/02 

FIELD: oil, gas and coke-chemical industries.

SUBSTANCE: invention relates to oil and gas industry, namely, to methods of mechanical cleaning of column walls by scrapers. Proposed method comprises lowering and lifting of mechanical scraper with sharpened blades to the well with the help of drive on pipes or on flexible rod with cleaning of the required interval of walls of well string. Preliminary investigations are used to define types of deposits and their proportional content deposited on walls of well string. Proceeding from these researches, a scraper is made with knives made in the form of cutting teeth uniformly located along perimeter and height of scraper. Teeth are sharpened in accordance with the type of deposits, and their number is selected in proportion to the number of corresponding deposits, wherein extreme teeth are made for processing metal, from which the well string is made, with possibility of removal of column metal of not more than 1 mm for the whole cleaning operation. Running-down of the scraper into the well is carried out with control of the lowered weight and at a rate excluding occurrence of landings. Clearing of required interval of walls of well string is performed with maintenance of liquid level in well above processing interval. Raising of the scraper is performed at a rate excluding occurrence of puffs and/or facilitating free flow of well fluid between scraper and walls of the well without piston effect. Load controlled by run-down weight is selected depending on allowable load on scraper, transportation pipes or flexible tie-rod.

EFFECT: enlarging functional capabilities due to use of special scraper edges for cleaning of well walls from deposits of any composition with protection against jamming due to use of required modes of lowering and lifting.

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