Subterranean wellbore tool

摘要

A subterranean wellbore tool comprising a tubular outer structure (112); a control member (120) movably supported in the outer structure (112); an indexing structure associated with the control member (120) and operative to sequentially drive it through a plurality of predetermined separate travel increments relative to the outer structure (112) in response to a corresponding successive plurality of increases in the pressure differential between the interior and exterior of the outer structure (112); and pressure diversion apparatus operative to permit flow of pressurized fluid within the outer structure (112) outwardly through a side wall portion thereof only after the control member (120) has been driven at least partially through its second or subsequent travel increment. <IMAGE>