CASING STRING REPAIR METHOD IN WELL (VERSIONS) Russian patent published in 2020 - IPC E21B29/10 

FIELD: mining.

SUBSTANCE: group of inventions relates to well workover, in particular, to methods of sealing recovery in case of casing string integrity violations. Proposed method comprises location of casing defective interval by geophysical survey, lowering and installation of additional casing with fixation in defective section of casing string. In compliance with first version, adhesion of cement ring with casing string along the whole length of casing string is additionally determined, if lower section of defective interval in casing string is located in interval of conductor and adhesion of cement ring with casing is absent, then casing is turned from mouth to coupling below lower section of defective interval and casing is removed from well. An additional column of similar design and length is lowered into the well instead of a casing string with a defective interval removed from the well. 5 m before reaching the upper end of the remaining casing string in the well, lowering the additional casing string is terminated and lowered to it at the end of the pipe string by a pencil outer diameter D with a conical surface narrowing downwards with diameter d at the lower end of the pencil-centrator. Centrator-pencil is installed in the well so that the pencil-centrator from below with the outer diameter D is placed in the remaining casing string in the well, and on top of outer diameter D is located in additional column, then additional column is pumped into well and additional column is screwed on upper end of remaining casing string in well, after which pipe string is removed with pencil-centrator from well. According to the second version, the centrator with outer diameter D₁ is arranged in the pipe string so that after the centrator is lowered into the remaining casing string, the centrator half length is located in the remaining casing string of the well, then additional casing string of similar design and length is lowered to the well to the upper end of the remaining casing string in the well, it is installed through the centrator with outer diameter D₁, additional column is screwed onto the upper end of the remaining casing string in the well.

EFFECT: improving quality and reliability of casing string sealing with disturbances on a long length, maintaining the internal flow section of the repaired casing string without limiting the functional possibility of using the technologies during the subsequent operation of the repaired well.

2 cl, 12 dwg