SOCAR has two oil refineries and one gas processing plant. Mohammedia has the largest oil refineries and other major industrial installations. Corbett helped ensure that the three petroleum refineries in Southeastern Pennsylvania would stay open. Russia has also recently built several major oil and gas refineries, plants and ports. These are large, expensive plants which are much like heavy oil refineries. It is heavily industrial with many oil refineries and brownfields. Valero owns two oil refineries in California. Cogeneration is still common in pulp and paper mills, refineries and chemical plants. Ethylene produced in this way competes with ethylene from oil refineries and fracking. Delayed coking is one of the unit processes used in many oil refineries. There are no oil refineries in Manitoba. There are no oil refineries in Missouri. BC has only two remaining oil refineries. Isobutane is the principal feedstock in alkylation units of refineries. Two of the site's oil refineries were destroyed.