Key Techniques of Selective Refracturing Tools

This paper presents the key techniques of selective refracturing tools used in avoiding initiating explosive devices in refracturing,and in prolonging the service life of hydraulic injection tools in single-run string.It also addressed solving the problems of large residual deformation of conventional expansion packer under pressure as well as stuck pipe,etc.The perforation channel and the fracturing channel of the refracturing tools were designed respectively,and channel conversion was realized through the joint mandrel of perforation and fracturing.According to the characteristics of channel conversion and operation,an integrated packer was designed,which could duly set and bridge over.In order to improve the bearing capacity and reduce deformation,an inserted spring structure was adopted in the design of the two ends of the element of the straddle packer.Indoor experiments and fields tests were carried out to verify the sealing performance and channel conversion capability of the packer of the selective refracturing tools.The results showed that the perforation and fracturing of the selective refracturing tools could be freely converted and selected.As a result,the new approach could reduce the volume of sand flowing through the single nozzle and extend the service life of the single-run string.In addition,the packer could duly set and unset.The residual deformation of the element is small and the element is reliable,which further facilitates the unsetting of the packer and the pulling out of the string.