Exxon Mobil is spending $20 billion through 2022 to expand its chemicals and fuel-making capacity in Texas and Louisiana to transform U.S. shale oil and natural gas into products for growing consumer markets in Asia. After decades of siting new plants to make plastics, industrial chemicals and motor fuels in the Middle East and East Asia, the shale boom is spurring Exxon to steer construction dollars back to its home country, Chief Executive Officer Darren Woods said in remarks prepared for the CERAWeek energy conference in Houston on Monday.