Understanding Price Elasticity of Supply
To elaborate on 123's comment, crude oil is extracted from the ground and can be manufactured/refined into a variety of produces (vehicle fuel/plastics/kerosene/etc.) If the price of kerosene increases, then it is natural for produces to want to substitute from producing plastic to producing more kerosene. Even if the supply of oil (of all varieties) is inelastic, the supply of individual oil-based products need not be.