Petrochemicals & NGLs
Natural gas liquids, olefins, aromatics, and polymers: from wellhead to plastic.
From Wellhead to Plastic
The NGL Barrel and Mont Belvieu
Natural gas comes out of the ground carrying heavier molecules dissolved in it. Gas processing plants strip those molecules out as a mixed stream called Y-grade, and fractionators then split the stream into five purity products: ethane, propane, normal butane, isobutane, and natural gasoline. Together these are the natural gas liquids, the NGL barrel, and each component has its own market. Ethane feeds petrochemical crackers almost exclusively. Propane splits between heating fuel, engine fuel, and chemical feedstock. The butanes go into gasoline blending and refinery alkylation, and natural gasoline is a blendstock and diluent for Canadian heavy crude.
The physical and pricing center of this market is Mont Belvieu, Texas, a small town east of Houston sitting on top of salt domes holding well over 100 million barrels of NGL storage. Pipelines from every major US shale basin converge there, fractionation capacity measured in millions of barrels per day surrounds it, and the price reporting agency OPIS assesses daily spot prices for each purity product traded in its caverns. A Mont Belvieu OPIS assessment is to NGLs what Henry Hub is to US natural gas: the reference everyone settles against, including the NYMEX futures.
How Shale Flipped the Cost Curve
Before 2010 the global petrochemical industry was organized around naphtha, a light oil refining cut, as the marginal feedstock. US crackers built to run ethane looked stranded as domestic gas production declined. Shale reversed that completely. Liquids-rich gas from the Permian, Marcellus, and Eagle Ford flooded the market with cheap ethane and propane, prices at Mont Belvieu collapsed toward the fuel value of the molecules, and US ethane crackers suddenly sat at the bottom of the global cost curve while naphtha crackers in Europe and Asia paid oil-linked prices at the top.
Capital followed. Between 2017 and 2023 the US Gulf Coast and Appalachia saw their largest cracker construction wave since the 1960s: Dow at Freeport, Chevron Phillips at Baytown, ExxonMobil and SABIC at Corpus Christi, Shell at Monaca in Pennsylvania, and several more, adding roughly 15 million tonnes a year of new ethylene capacity. When domestic crackers could not absorb all the ethane, exporters built terminals and a fleet of very large ethane carriers to ship it to crackers in India, China, and Europe. The US went from rejecting ethane into the gas stream to exporting roughly 580,000 barrels of it a day by 2025.
Steam Cracking 101
A steam cracker is a furnace that heats a hydrocarbon feed with steam to roughly 850 degrees Celsius for a fraction of a second, breaking the molecules apart, then quenches and separates the fragments. The feedstock slate determines the product slate. Crack ethane and the output is almost all ethylene, with little else. Crack naphtha and only about a third of the output is ethylene; the rest is a spread of propylene, butadiene, and pyrolysis gasoline rich in aromatics. This co-product arithmetic drives the whole market: as the US and Middle East shifted toward light ethane feeds, the world made relatively less propylene, butadiene, and benzene per tonne of ethylene, and on-purpose technologies such as propane dehydrogenation grew to fill the gap.
Two families of building blocks come out of this system. The olefins, ethylene and propylene, are reactive double-bonded molecules that polymerize into polyethylene and polypropylene and feed hundreds of derivatives. The aromatics, benzene, toluene, and the xylenes, are ring-shaped molecules sourced mainly from refinery reformers and cracker pyrolysis gasoline, and they feed styrene, polyester, nylon, and polycarbonate chains. Almost every plastic, foam, fiber, and coating in daily life starts as one of these five or six molecules.
How Petrochemicals Trade
Petrochemical markets sit between the transparency of oil futures and the opacity of pure physical trade. The NGLs are the most financial: NYMEX lists cash-settled Mont Belvieu ethane and propane futures that settle against OPIS monthly average assessments, and the propane contract in particular carries real open interest from producers, exporters, and trade houses. Olefins and aromatics trade mostly as physical spot and contract volumes assessed daily by price reporting agencies, chiefly S&P Global Commodity Insights, ICIS, and OPIS PetroChem Wire, with a thinner layer of cleared swaps and futures referencing those assessments.
Polymers add one more layer: most polyethylene and polypropylene moves on monthly contract prices negotiated between producers and converters, with spot and export cargoes assessed by the PRAs around them. The deepest polymer futures in the world are not in the West at all; the Dalian Commodity Exchange in China lists linear low density polyethylene and polypropylene contracts that trade enormous volumes and increasingly set the marginal price signal for Asian resin.
Oversupply, China, and the Demand Engine
The defining feature of the mid-2020s petrochemical market is structural oversupply. China spent the decade building self-sufficiency: a wave of propane dehydrogenation plants, giant mixed-feed crackers attached to new refineries, and coal-to-olefins capacity. Between 2020 and 2026 China added more ethylene capacity than the entire installed base of Europe. Global operating rates for ethylene fell to around 80 percent, the weakest sustained stretch since the early 1980s, margins at naphtha crackers in Europe and Northeast Asia went negative for long periods, and a round of permanent cracker closures began in Europe in 2024 and 2025.
Demand keeps growing through it all. Plastics and other petrochemicals are the largest single engine of oil demand growth this decade; the IEA projects petrochemical feedstocks will account for the majority of net oil demand growth through 2030 as fuel demand flattens. That tension, relentless volume growth against relentless capacity growth and rising recycling and packaging regulation, is the trade in this group.
Fact Sheets
The molecule America once burned as gas now crosses oceans in purpose-built ships to feed the world's crackers.
One molecule, two lives: rural heating fuel in a Minnesota winter and cracker feedstock in a Shandong PDH plant.
The most produced organic chemical on earth, and in 2026 there is far too much capacity to make it.
Once a refinery afterthought, propylene is now made on purpose in dedicated plants, mostly in China, mostly unprofitably.
The six-carbon ring at the root of styrene, nylon, and polycarbonate, pulled between the chemical industry and the gasoline pool.
The two plastics that wrap, carry, and contain the modern world, now trading futures in Dalian deeper than any Western resin market.