U.S. lawmakers are toughening their stance on Iran’s energy industry with new economic penalties, but experts doubt the Islamic regime will pay much attention and is more likely to open the doors even wider to other players eager to replace fleeing investors. Long on Congress’ radar screen, Iran is being targeted by two bills: The Senate’s Dodd-Shelby Comprehensive Iran Sanctions, Accountability and Divestment Act passed in late January; and the House’s Iran Refined Petroleum Sanctions Act approved in December. The bottom line is these bills, once signed into law by President Obama, will pursue financial institutions and businesses that do...