The Dow Chemical Co. and Saudi Arabian Oil Co. (Saudi Aramco) have launched a joint venture to build a $20 billion petrochemical plant in Jubail, Saudi Arabia.

The companies’ respective boards have already approved the deal — which was announced July 25 — to create what will be known as the Sadara Chemical Co. Construction of the Sadara complex, envisioned as one of the world’s largest facilities for integrated chemicals, is to begin immediately and slated to begin production by the second half of 2015. The companies expect the project to be fully operational by 2016.