METHOD OF REPAIRING CASING STRING IN NON-CEMENTED PART (EMBODIMENTS) Russian patent published in 2020 - IPC E21B29/10 E21B33/14 

FIELD: mining.

SUBSTANCE: group of inventions relates to well workover, in particular, to tightness recovery technologies. When implementing the method, the non-cemented interval of the casing string is determined, the disturbance in the non-cemented part is determined by the pressure test, the presence or absence of its movement is determined by string tension. If the string movement during tension is, and the specific intake capacity of the disturbance is g < 0.5 m³/(hMPa), the repair is performed by turning the threaded joints with the spinning moment of 4300–6000 N/m depending on the external diameter of the column. If the specific throttle response g >0.5 m³/(hMPa) and/or the hydraulic fracturing pressure of the surrounding rocks in the fault interval is less than 50 % of the pressure of the pressure test of the column, then the lap of the upper part of the column with disturbances is sealed with a lap and replaced with an additional column of similar design and length with its subsequent fixation with a threaded connection remaining in the well. For this purpose, the production string is stretched with force equal to the weight of the turned part of the column, and by turning to the left, the column is turned off, maintaining constant load upwards, after which the column is lifted by 0.5–1.0 m and lowered downwards. If there is no movement of the string during tensioning, the casing is pressure plugged through disturbance irrespective of the injectivity. If the specific intake capacity of the disturbance is g < 0.5 m³/(hMPa), the acid disturbance is pre-drained in volume of 1.5 m³ until specific permeability g > 0.5 m³/(hMPa) is achieved, if the above specific intake is not achieved, special holes in the casing string in the interval of violation. If specific rate of inhomogeneity g > 2.0 m³/(hMPa), simultaneously with plugging under pressure filler is injected, and with specific hysteresis of g > 3.0 m³/(hMPa) prior to plugging, water-swellable polymer is pre-pumped to achieve intake capacity of 0.5 m³/(hMPa) to 2 m³/(hMPa). After plugging into the casing string of the injection well the string of tubing with the packer is lowered, and in the production casing of the production well after plugging the inflow of liquid from the disturbance by the decrease in the level in the casing is determined. If liquid inflow from disturbance is not more than 10 % of well flow rate, then casing string is repaired, if more than 10 %, then repeated plugging is performed.

EFFECT: higher reliability and quality of repair of casing string in uncemented part produced without narrowing of flow section and without limitation of functional capabilities of use of technologies during subsequent operation.

2 cl, 7 dwg