Method and Apparatus for Catching Darts and Other Dropped Objects
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.
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.