In upstream oil & gas gas obtained from boreholes and wells and consisting primarily of hydrocarbons [Section 3(c), Oil Exploration and Development Act of 1972]
In oil & gas, natural gas: gas consisting primarily of a mixture of methane, ethane, propane, and butane, with small amounts of heavier hydrocarbons and some impurities, consistent with PNS or other applicable internationally accepted industry standards [Section 4(p), Philippine Natural Gas Industry Development Act; Section 4(w), DOE Department Circular No. DC 2025-04-0005, Philippine Natural Gas Industry Development Act IRR]
Note: In the Philippine Natural Gas Industry Development Act and its IRR, the term is written as “Natural Gas”.