Importance

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Abstract

A differential pressure actuated vent assembly is connected into an oil well tool string. In one form of the invention, the tool string includes a packer device, a perforating gun attached to the lower end of the tubing string, with the vent assembly being interposed between the gun and the packer device. Fluid pressure within the tubing string is effected on one face of a piston associated with the vent assembly, which reciprocates the piston and communicates the interior of the tubing string with the annulus around the tubing string while carrying out the step of perforating the formation. Movement of the piston and the subsequent detonation of the gun preferably are both accomplished sequentially in response to the dropping of a bar down through the tool string. The bar opens a passageway leading to the piston, and immediately thereafter, before the pressure differential between the interior of the tubing string and the annulus is equalized, the gun is detonated, thereby obviating damage to the formation.

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First Claim