 Limited quantities of rye, wheat, oats, barley and vegetables are grown, although the growing season averages less than 100 days.Following the collapse of the Soviet Union and economic liberalization, Sakhalin has experienced an oil boom with extensive petroleum exploration and mining by most large oil multinational corporations.The oil and natural gas reserves contain an estimated 14 billion barrels (2.2 km3) of oil and 2,700 km3 (96 trillion cubic feet) of gas and are being developed under production-sharing agreement contracts involving international oil companies like ExxonMobil and Shell.