shale gas composition

Shale Gas Composition – What it’s made up of

Marcellus Shale Gas Well
Photo by WCN 24/7

Shale gas is a valuable natural resource that is being eagerly sought out and drilled for using fracturing techniques. But just what does natural gas in shale rock contain?

Natural shale gas is mainly composed of methane, although it might also contain compounds that energy companies have to separate from methane to make the gas usable commercially. These impurities may be different in each well and reservoir.

The other compounds found in shale gas include natural gas liquids, which are hydrocarbons of a heavier nature that will be separated in processing plants as liquids. These liquids include heptane, hexane, pentane, butane and propane. Shale gas also includes condensates and water.

The gaseous components of raw shale gas include Sulfur Dioxide, Hydrogen Sulfide, Helium, Nitrogen and Carbon Dioxide. Mercury may also be found in smaller concentrations in most reservoirs where natural gas is obtained. The mercury found will be lowered in concentration until it’s below the detectable threshold of one part per trillion (ppt).

The make up of Natural Shale Gas

Natural gas and shale gas may also refer to gas that is commercially viable, after the impurities have been removed. When gas is delivered to customers who use it, the characteristics may vary, depending upon the raw natural gases. The full list of composition ingredients also includes iso-Butane and Oxygen.

Gas in shale deposits occurs naturally, but in different areas, it may contain different percentages of the same basic compounds. Their analysis may be very similar, but they are not the same, not entirely. There is no system average to account for the variables in the composition of natural gas. Different supplies of natural gas were formed in different areas, so the exact composition depends on the region in which the gas originated. Ultimately, the heating value of shale gas depends on the exact mixture of gas suppliers in a given area.

Natural shale gas as it is found at a wellhead is different from that which consumers receive, and is much less pure. Some of the variations depend on the type of well that the gas comes from. It may come from gas wells like fracking wells, oil wells or condensate wells. Natural gas found in oil wells is usually separate from any oil found in the well, and may be known as “associated gas”. Sometimes this gas is dissolved within crude oil, which is not usually the case in shale fracking wells. Typical gas wells will produce raw gas without crude oil, and condensate wells produce natural or shale gas found with hydrocarbon condensate.