GEISMAR- Shell Chemical LP is starting a $717 million expansion at its plant in Geismar.
    
Shell officials and Gov. John Bel Edwards say it will create 1,500 construction jobs and add 20 permanent jobs when it opens in 2018. Salaries for the permanent jobs average $104,000 a year.
    
About 650 people already work at the plant.
    
Officials say the expansion will make the 800-acre complex the world's largest producer of a group of chemicals used to make various consumer and industrial products, including packaging plastics, synthetic lubricants, drilling fluids and household detergents.
    
Officials say the expansion will bring total production capacity to 425,000 tons of alpha olefins a year.
    
A news release says Shell will use Louisiana's workforce development program and is expected to use its enterprise zone and industrial tax exemptions.