Abstract: A well system includes a valve interconnected in a casing string and selectively configurable between first and second configurations via a line external to the casing string, the valve in the first configuration being operable to selectively permit and prevent fluid flow between the casing string exterior and interior, and in the second configuration to selectively filter and prevent fluid flow between the casing string exterior and interior. A method of selectively stimulating a formation includes: positioning a casing string in a wellbore intersecting the formation, the casing string including a valve operable via an external line to selectively permit and prevent fluid flow between the casing string interior and exterior; and stimulating an interval set of the formation by opening the valve, flowing a stimulation fluid from the casing string into the interval set, and then configuring the valve to filter formation fluid which flows into the casing string.