The petrochemical industry is booming in the US – largely fuelled by the low cost of shale gas and shale gas liquids as a feedstock. New drilling and exploration techniques enable natural gas and liquids to be extracted cost effectively from shale rock and when employing state-of-the art cryogenic gases technology, even wet shale gas basins can now be developed efficiently to deliver valuable natural gas liquids (NGLs) for various industries.
While natural gas reserves occur in many other parts of the world, it is in the US where industry is most determined to develop unconventional sources of natural gas in order to reduce dependence on energy imports. But shale gas is a lot more than just a source of energy. Not only is it an ideal fuel for power plants and district heating, it also delivers valuable feedstock such as ethane for the petrochemical industry. Natural gas can be easily converted into base chemicals such as ethylene, which is a hydrocarbon compound and precursor of many common chemicals. The best known are probably the plastics found in everything from packaging and cable insulation through car seats to toys. The American Chemistry Council (ACC) estimates that the shale gas boom has so far fuelled investments to the tune of around US$179 billion in the US petrochemical industry alone.1 Much of the investment is geared toward export markets for chemistry and plastics products. Yet gas fields that will be of real interest to ethylene producers are still at the very early stages of development. Ethylene produced from shale gas has the potential to unleash a new industrial revolution in the US.
Before that can happen, however, there are hurdles to overcome. The shale gas liquid recovery processes typically used thus far are not the most efficient. Efficient processing of these valuable raw materials calls for highly specialised know-how as the quality of shale gas reserves can vary significantly from one shale basin to another.
Wet shale gas is a much more interesting prospect for the petrochemical industry than dry shale gas, as these reserves contain extremely valuable raw materials. Their composition can vary dramatically. Wet shale gas contains less methane, but higher concentrations of ethane (C2) and longer-chain hydrocarbons, such as propane (C3) and butane (C4) , and higher molecular weight hydrocarbons. Referred to as NGLs, they are the perfect feed for gas crackers, which produce ethylene. This translates into a huge market opportunity.
Unconventional reserves present a number of challenges to chemical engineers, however. Wet shale gas is occasionally contaminated with impurities such as trace amounts of mercury and, sometimes, hydrogen sulfide (H2S) as well as carbon dioxide (CO2). These substances must be almost completely removed before the ethane and propane in the shale gas can be fed to an olefin plant. Cryogenic condensation technology that was originally designed for the recovery of…
Written by Tina Edvardsson, Linde Engineering North America, USA.
- 'Fact Sheet: U.S. Chemical Industry Investment Linked to Shale Gas – $179 Billion and Counting', American Chemistry Council, (28 March 2018).
Read the article online at: https://www.hydrocarbonengineering.com/gas-processing/31072017/the-shale-treasure-hunt/