A formation isolation valve for underbalanced drilling applications. A system for operating a formation isolation valve includes the valve interconnected in a casing string. An assembly displaces through the casing string, thereby causing the valve to open prior to the assembly reaching the valve. An operating system includes a well tool with an actuator positioned downhole. A device for causing the actuator to operate the well tool is also positioned downhole remote from the actuator. A method of operating a well tool includes the steps of: positioning the well tool in a well, the well tool including an actuator; positioning a power source for the actuator in the well; and at a downhole position remote from the actuator, causing the actuator to operate the well tool.
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