Patent ID: 8534360
Filing Date: 2013-09-17
Classification: E21B

Abstract:
1. A wellbore ball valve, comprising: a ball-type valve closure having an interior, central bore; a ball carrying assembly defining an annular, sealing seat surface in contact with and adapted to seal with the exterior of the valve closure, the seat surface defining a first through hole that communicates with the central bore when the valve closure is open and is sealed from the central bore when the valve closure is closed; an upper assembly defining an annular ball contacting surface in contact with the exterior of the valve closure, the ball contacting surface defining a second through hole that overlaps an opening of the central bore when the valve closure is open and does not overlap the opening of the central bore when the valve closure is closed, the second through hole being shaped differently from the first through hole in that it at least partially overlaps with the central bore while the first through hole is sealed from the central bore when the valve closure is between open and closed; and the second through hole being larger than the first through hole, and the valve closure rotating in a first direction when changed from closed to open and the second through hole being larger in a greatest dimension measured parallel to the first direction than a greatest dimension measured transverse to the first direction.