Kajian Emisi Gas Buang Pada Sektor Hulu Migas Untuk Mendukung Tercapainya Sustainable Energy Dengan Menggunakan Pendekatan Simpel LCA (Life Cycle Assesment) = Gas Flare and Venting Impact Evaluation through Simple LCA (Life Cycle Assessment) Approach to Achieve Sustainable Energy in Oil & Gas Upstream Operation: Case Study at PO Company.