Alaska Natural Gas Pipeline Improvement Act of 2011 - Amends the Alaska Natural Gas Pipeline Act of 2004 to include in the Alaska Natural Gas Transportation Project (carrying Alaska natural gas to the Canadian border) any pipeline segment that the Federal Energy Regulatory Commission (FERC) finds could feasibly be incorporated into and serve as an integrated segment of that system, regardless of whether it: (1) is proposed and constructed before construction of the entire system, or (2) initially transports natural gas solely for delivery to customers within Alaska.