| 摘要 |
A retrievable gravel packer for placing a gravel pack in a wellbore about a gravel screen disposed therebelow across a producing formation, comprising: a mandrel assembly (12) including first and second sugstantially concentric tubular mandrels (220;110,170,200) extending from the upper end to the lower end thereof defining a mandrel annulus (1002) therebetween, and closeable crossover means (20) at the upper end of said assembly for communicating said mandrel annulus with said wellbore; a housing assembly (14) disposed about said mandrel assembly including a compressible packer element (310) and packer element compression means (294); and a circulation assembly (16) disposed at the lower end of said mandrel assembly including a circulation housing (422) having circulation ports (427) in the wall thereof and secured to said second mandrel, a circulation mandrel (428) secured to said first mandrel and disposed within said circulation housing to define a circulation annulus (1002) therebetween in communication with said mandrel annulus, said circulation mandrel having relief ports (456) extending from the interior of said circulation mandrel through the wall thereof to said circulation annulus, said circulation mandrel further including lateral circulation channels (434) through the wall thereof extending from said circulation ports of said circulation housing to the interior of said circulation mandrel, the bore thereof being in communication with the bore of said first mandrel, first valve means (460) slidably disposed in said circulation mandrel for closing circulation through said circulation channels (434), second valve means (446) slidably disposed within said circulation mandrel for opening communication through said relief ports (456), a check ball (498) at the lower end of said gravel packer, and check ball release means (448) for selectively releasing said check ball from said gravel in packer.
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