Natural gas liquids, or NGLs, are the heavier hydrocarbons that come out of the ground with natural gas and are recovered as liquids at a gas plant. They are valuable products in their own right - ethane, propane, butane, and heavier - sold separately from the sales gas. This guide explains what NGLs are, how they are recovered and fractionated, and why they matter economically.
Natural Gas Liquids (NGL) in one line: Natural gas liquids (NGLs) are the hydrocarbons heavier than methane found in natural gas - ethane, propane, butanes (normal and iso), and pentanes-plus (natural gasoline). They are recovered from the gas stream at a gas plant as liquids, then fractionated into individual products that are sold separately from the residue sales gas.
Natural gas is mostly methane (C1), but raw gas also contains a spread of heavier hydrocarbons: ethane (C2), propane (C3), normal butane and isobutane (C4), and pentanes and heavier lumped together as pentanes-plus or natural gasoline (C5+). Under reservoir and pipeline conditions these ride along in the gas, but they are far more valuable recovered as liquids. Collectively they are the natural gas liquids. They must be removed anyway to meet the sales-gas hydrocarbon dew-point spec, so recovery serves double duty.
NGLs sit between dry natural gas and crude oil in the hydrocarbon spectrum. They are distinct from LNG - LNG is methane liquefied by deep cooling for transport and is still just natural gas, whereas NGLs are heavier compounds that are liquid at far milder conditions and are separate marketable products. They are also distinct from condensate, though pentanes-plus and condensate overlap; condensate is typically the liquid that drops out at the wellhead or separator, while NGLs are recovered from the gas phase at the plant.
NGLs are pulled out of the gas by cooling it enough that the heavier components condense. Simple plants use refrigeration; modern plants use cryogenic recovery - a turboexpander drops the gas to very low temperatures (well below -100 F) so even ethane condenses, in a cold-box and demethanizer arrangement. What comes off is a mixed NGL stream often called Y-grade or raw make - all the recovered components blended together.
That mixed stream is then fractionated: a train of distillation columns (a deethanizer, depropanizer, debutanizer, and so on) separates it into purity products - ethane, propane, normal butane, isobutane, and natural gasoline - each drawn off in sequence as the mixture is boiled at progressively higher temperatures. Each finished NGL product then goes to its own storage and pipeline or truck for sale.
NGLs are a major revenue stream. Ethane is a feedstock for petrochemical crackers making plastics; propane is heating and cooking fuel and a petrochemical feed; butanes go into gasoline blending, refinery alkylation, and LPG; natural gasoline blends into fuels. Recovering more NGLs (deeper ethane recovery) versus leaving them in the gas is a live economic decision - operators run ethane recovery or ethane rejection depending on the relative price of ethane as a liquid versus its heating value in the gas.
A gas plant's NGL recovery and fractionation are heavily instrumented: column temperatures and pressures, reboiler and condenser duties, product flows, and analyzers on each product. A cloud SCADA such as Merobix reads those temperature, pressure, flow, and analyzer tags from the plant's controllers and flow computers over Modbus, DNP3, OPC UA, or similar. Trending recovery, product rates, and column conditions remotely helps operators run the plant to the current ethane-recovery economics and confirm each NGL product is meeting its own specification.
The hydrocarbons heavier than methane in natural gas: ethane (C2), propane (C3), normal butane and isobutane (C4), and pentanes-plus or natural gasoline (C5+). They are recovered from the gas as liquids at a gas plant and then fractionated into these individual products, each sold separately from the residue sales gas.
LNG is natural gas (mostly methane) that has been cooled to about -260 F to become liquid for transport - it is still just natural gas. NGLs are heavier hydrocarbons (ethane through pentanes-plus) that are liquid at much milder conditions and are separate marketable products like propane and butane. LNG is liquefied methane; NGLs are different, heavier compounds.
By cooling the gas until the heavier components condense. Modern plants use cryogenic recovery with a turboexpander that drops the gas well below -100 F so even ethane liquefies, in a cold-box and demethanizer. The recovered mixed NGL stream (Y-grade) is then fractionated in a series of distillation columns into individual products.
They are two operating modes. In ethane recovery, the plant runs cold enough to condense and sell ethane as a liquid. In ethane rejection, ethane is deliberately left in the gas stream where it adds heating value to the sales gas. Operators choose based on economics - whether ethane is worth more as a recovered liquid or as energy in the gas.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
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