a subterranean well assembly and method of installation which uses a selectively rupturable flow control device to initially block flow and after rupture to allow flow therethrough . the selectively rupturable device is eccentric , in that , it withstands higher pressures without rupture in a flow direction which ruptures when lower pressures are applied to the device in the opposite direction . the rupturable device is installed in a subterranean well in the flow path between the production tubing string and casing .