The existence of under-exploited gas reserves in the kingdom has been one of the strongest arguments for developing gas-based heavy industries.5 In general terms, the theory indicates that Saudi Arabia should establish and promote industries primarily based on natural gas and I or oil.For example, according to the Heckscher-Ohlin theory of international trade, a country tends to have lower comparative costs in the commodity that uses the largest amount of the relatively cheapest factor in its economy.Gas - especially the dry gases, methane and ethane - is an expensive product to transport, thus making it sensible to look for more productive uses for its exploitation.These considerations provide the fundamental rationale for specialization.