PITTSBURGH (AP) - Shell Oil Co. says it has chosen a site near Pittsburgh for a major new petrochemical refinery that could provide a huge economic boost to the region.

Dan Carlson, Shell's General Manager of New Business Development, said Thursday that the energy company signed a land option agreement with Horsehead Corp. to evaluate a site near Monaca. That's about 35 miles northwest of Pittsburgh.

The decision is a victory for Pennsylvania, which had offered major incentives for the plant and was competing with Ohio and West Virginia.

Shell says it could spend several billion dollars to build an ethylene cracker plant that converts natural gas liquids to products including plastics, tires and antifreeze.

But Shell says construction of a plant is years away. The next steps are environmental and design studies and further economic analysis.

(Copyright 2012 by The Associated Press. All Rights Reserved.)