Because of the difficulty for obtaining figures for NGL production, the volumes of the world's total NGL production shown in [[:file:St54Ch3Figure21.jpg|Figure 1]] had to be estimated, assuming an average liquids-to-gas ratio of 22.5 bbl of NGL per mmcf of gas. In the United States, where better information is available, the average NGL yield of natural gas is higher: 35-40 bbl per mmcf. The ratio, of course, varies from petroleum field to petroleum field and from country to country, and the overall world average can only be calculated based on reliable statistics for gas and NGL, statistics that are not always readily available. | Because of the difficulty for obtaining figures for NGL production, the volumes of the world's total NGL production shown in [[:file:St54Ch3Figure21.jpg|Figure 1]] had to be estimated, assuming an average liquids-to-gas ratio of 22.5 bbl of NGL per mmcf of gas. In the United States, where better information is available, the average NGL yield of natural gas is higher: 35-40 bbl per mmcf. The ratio, of course, varies from petroleum field to petroleum field and from country to country, and the overall world average can only be calculated based on reliable statistics for gas and NGL, statistics that are not always readily available. |