Casey’s General Stores Inc. has completed its acquisition of Buchanan Energy, owner of Bucky’s Convenience Stores. The acquisition expands Ankeny-based Casey’s presence in the Midwest, particularly in Nebraska and Illinois. Casey’s now owns and operates more than 2,300  stores. It will divest six stores as part of the consent order the company agreed to with the Federal Trade Commission, which will not materially alter the expected financial impact of the transaction that was announced in November.