PETROLEUM GEOLOGY/Chemical and Physical Properties 255 Table Oil classification according to source type Typical characteristics at moderate maturitya Marine carbonate or siliceous Marine siliciclastic Lacustrine Coal API Wax Sulphur Nitrogen Ni ỵ V Ni/V 25 35 30 30 Low Low High High High Moderate low Low Low High Moderate Moderate Low 50 300 50 50 $0