DIAGNOSTIC METHOD OF CASING STRING-BOREHOLE ANNULUS TIGHTNESS Russian patent published in 2008 - IPC E21B47/10 G01V5/04 

FIELD: mining.

SUBSTANCE: it is made background gamma logging, pumped back from casing pipe string into planned perforation interval grouting mortar (GM) with gaseous chemically inert long-living radioisotope - crypton and made gamma logging after formation of cement brick (CB) and gamma logging after defined time periods. Then it is specified start moment of behind-the-casing flow according to comparison results of check gamma loggings with background. At that crypton is introduced into GM portion, located in planned perforation interval. After gamma logging holding casing is perforated against "marked" CB and well is developed. After it into perforation interval is pumped and broken through stratum short-lived gaseous chemically inert radioisotope - radon in amount 0.37 Bq and again is replicated gamma logging in perforation interval.

EFFECT: ability of cementation quality definition; early recognition of cement brick fracture initiation and appearance of behind-the-casing flows and point of water entry into extracted production.

3 cl