METHOD OF ELIMINATION OF BEHIND-CASING FLOW IN WELLS OF SMALL DIAMETRE Russian patent published in 2009 - IPC E21B33/14 

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil industry, particularly to methods of elimination of behind-the-casing flows at repair of wells of small diametre. The method of eliminating behind-the-casing flows in the wells of small diametre consists in forming a cavity in a wall of the well and in plugging behind-the-casing space with cement grout. The cavity is formed by means of solving rock with an acid composition and in pumping it via a flow string into space between a producing well and the wall of the well in an interval of behind-the-casing flows, in pumping for the purpose of driving mineralised water with density equal to density of acid composition, in well shut-down for reacting and in following driving of products of acid composition reaction and rock of neutral buffer fluid into a reservoir, and in the said plugging. Volume of acid composition is not less, than volume of space between the well wall and the producing column with length equal to length of the interval of behind-the-casing overflows.

EFFECT: increased duration of effect from operations of eliminating behind-the-casing overflows due to increased mechanical strength of cement ring.

2 cl, 1 ex