| 摘要 |
Method and apparatus by which a gun firing head is maintained free of debris. An upper tubing string runs downhole in a cased borehole to a packer device. A jet gun, having a firing head located at the upper end thereof, is connected to a lower tubing string. A vent assembly is connected in series relationship within the lower string, and underlies the packer device. A barrier is contained within the lower tubing in underlying relationship to the vent and isolates the tubing interior immediately above the gun from contact with well fluids. A gun firing device is run from the surface, downhole through the packer device, and penetrates the barrier to gain access to the gun firing head, whereupon the gun is detonated, thereby perforating the casing and penetrating the payzone. Production occurs back through the perforations, up through the lower annulus, into the vent, and up the lower tubing string, through the packer, and up through the upper tubing string to the surface of the earth where the production is gathered.
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