Natural Gas Liquid Reserves in the US
When natural gas comes out of the ground it almost always contains traces of larger natural gas molecules – ethane, propane, butane and benzene –in addition to methane, the simplest gas molecule. These other gases are valuable commodities and must be extracted, along with other impurities, before the gas is considered “pipeline quality.”
The non-methane hydrocarbons are generally referred to as “natural gas liquids” (NGL), even though some of them remain gases at room temperature. Various gas basins hold different percentage of NGL, according to the pressure and age of the field. The map shows the percentage for the various gas basins across the country. Those with percentage of 2.9 and above are shown in the darker green. Those with percentage of 1.8 to 2.8 are shown in medium green. Those below 1.0 and 1.8 are shown in pale green and those below 1.0 are unshaded. There are two very small strata with NGL ratios of more than 5 percent. These are the Eagle Ford basin in South Texas (5.2) and the Granite Wash Basin in Oklahoma (5.3). These are shown in a very dark green.
The interesting pattern is that most elevated NGL reserves lie in the Midwest from Texas to North Dakota. Although the Marcellus Shale along the Appalachian Chain is a current center of gas drilling, it is not very high in NGL. As gas production has tapered off in the last year (see Charticle 2), some of the cutting back has taken place in the Marcellus precisely because the price of liquid products has not yet declined and NGL is proving more valuable.
OPEC produced 5.7 thousand barrels per day (mbd) of NGL, 1.5 of this coming from Saudi Arabia. The US is producing about 2.5 mbd, a figure that will probably rise as methane production continues to increase. We do not import any LNG and may soon be exporting to Canada since their production has been declining.
