Practice of Sealed Coring Technology in Shale Formation of Well H1

Well H1, which was completed at well depth of 3 001 meters, is the first shale gas exploration well in block X. Sealed coring operation has been conducted in this well for 5 times. In view of the problems of tight shale formation, big angle of bedding, poor rock drillability, a series of technical measures have been taken such as optimization of closed coring method, optimization of sealing fluid and coring bit, optimization make up of string, reasonably controlling of coring drilling parameters, taking refining operations etc. These technical measures solved successfully the problem of big angle of bedding, broken formation, and low core drilling rate, easily jammed etc. The footage of sealed coring is 32.83 meters and core recovery is 98%, which improved greatly core drilling efficiency of shale formation.