Energy sources 18 Fuentes de energa̕ Industria del petrl̤eo Petroleum industry 18 Combustibles 15 Combustibles fs̤iles 15 Fossil fuels 15 more ... Fuels 15 Energa̕ 14 Energy 13 Petrl̤eo 13 Oil 9 Industria petroqum̕ica 8 Petrochemical industry 8 Gas natural 6 Natural gas 6 Upstream 6 Environment 5 Medio ambiente 5 Oil production 5 Petroleum 5 Produccin̤ de petrl̤eo 4 Exploracin̤ 3 Exploration 3 Operaciones 3 Operations 3 Petroleum refining 3 Petroleum technology 3 Procesos 3 Processes 3 less ...