SEALING METHOD OF PRODUCTION STRING Russian patent published in 2014 - IPC E21B33/122 

FIELD: oil and gas industry.

SUBSTANCE: sealing method of a production string involves lowering of two packers on a setting tool to a production string of the well, their setting in the production string above and below the leakage interval with further removal of the setting tool. Packers are connected to each other with a pipe. Before leakage of the production string occurs, chemical composition of the formation fluid is analysed by sampling. Then, the following arrangement is assembled on the well head in upward direction: lower packer, pipe, upper packer, left adapter and separating valve. The arrangement is lowered on the setting tool to leakage interval of the production string. Then, setting of packers is performed. After that, the separating valve is brought into action, which hydraulically separates the arrangement from the setting tool and connects inner spaces of the setting tool to the interstring space of the well above the upper packer. Then, well fluid level above the upper packer is decreased by swabbing along the setting tool, and tightness of the upper packer seating fit is determined. If the upper packer seating fit is non-tight, packers are broken up and the whole arrangement is taken for inspection; after that, the above operations are repeated till the upper packer seating fit is tight. If the upper packer seating fit is tight, the setting tool is rotated in a clockwise direction from the well head and the setting tool with the separating valve and the left-hand adapter is unscrewed. The setting tool with the separating valve and the left-hand adapter is removed from the production string to surface. The well is put into operation and repeated analysis of chemical composition of formation fluid is performed by sampling. Tightness of the lower packer seating fit is determined by comparing the analysis results of the chemical composition of formation fluid in initial and repeated samples. If the lower packer seating fit is non-tight, repeated sealing of the production string is performed as is described above from lowering of the arrangement to the leakage interval of the production string to determination of tightness of the lower packer seating fit.

EFFECT: improving effectiveness of the method's implementation owing to providing tightness of a production string and simplifying the method's implementation process per lower and lifting operation.

4 dwg