| 摘要 |
A specially designed rotary indexing system and associated operational methods are incorporated in a downhole control device, representatively a sliding sleeve valve, having an outer tubular member (41) in which an annular plug seat (42) is coaxially disposed. The plug seat (42) is resiliently expandable between a first diameter and a larger second diameter and is illustratively of a circumferentially segmented construction. The rotary indexing system is operative to detect the number of plug members (50) that pass through and diametrically expand the plug seat (42), and responsively preclude passage of further plug members (50) therethrough when such number reaches a predetermined magnitude. Such predetermined magnitude is correlated to the total rotation of an indexing system counter ring portion (55) rotationally driven by axial camming forces transmitted to the rotary indexing system by successive plug member (50) passage-generated diametrical expansions of the plug seat (42). |
