Method and Apparatus for Catching Darts and Other Dropped Objects

Abstract

A dart or other dropped object having a shearable sleeve member is dropped or launched down hole, typically during cementing operations, until it lands on a seat within a dart catcher receptacle. By increasing a pressure differential across the landed dart to a predetermined amount, the shearable sleeve member shears from the dart. The dart extrudes through the still-seated stationary sleeve member and passes to a ported catcher sub. A first alternative embodiment utilizes a novel collet member as a seat in a dart catcher receptacle, while a second alternative embodiment utilizes a resilient flexible seat member.

What is claimed: 
     
         1 . A dart catcher assembly comprising:
 a) a housing having a central through bore, wherein a portion of said through bore has a reduced internal diameter defining a seat;   b) a dart; and   c) a sleeve member removably attached to said dart, wherein the outer diameter of said sleeve member is greater than the internal diameter of said seat.   
     
     
         2 . The dart catcher assembly of  claim 1 , wherein said sleeve member is attached to said dart using at least one shearable fastener. 
     
     
         3 . The dart catcher assembly of  claim 2 , wherein said shearable fastener comprises a shear screw, shear pin or shear ring.