油藏物理学一天然气的高压物桂 relative density:Y=Pg/Pa The relative density is the density of nature gas over the density of dry air in standard conditions(293K and 0.101MPa). We can approximatively express the equation. y≈M/29 y∈[0.50.7]油藏物理学——天然气的高压物性 relative density：γ =ρg / ρa The relative density is the density of nature gas over the density of dry air in standard conditions(293K and 0.101MPa).   M / 29  [0.5～0.7] We can approximatively express the equation