A well casing or liner shoe (10) comprises a partially of fully openable central fluid channel (13) which is connected to at least one small width nozzle (46) and an additional large width fluid outlet (49), which is closed by a thin walled closure device arranged to open at a selected fluid overpressure in the fluid channel (13), and which has a flow area larger than each nozzle (46) to permit fluid circulation when the nozzles (46) are clogged and clearance of clogging debris through the additional large width additional fluid outlet (49).