Downstream oil and gas is the stage of the energy industry that takes crude oil and raw natural gas and turns them into finished products you actually use: gasoline, diesel, jet fuel, heating oil, plastics, and more. It covers everything from refining to distribution to the gas station where you fill your tank. The upstream sector extracts oil from the ground, the midstream sector moves it through pipelines, and the downstream sector transforms it into something useful and gets it to consumers.
What the Downstream Sector Covers
The downstream sector has two broad halves: refining and marketing. Refining is the industrial process of converting crude oil, which is virtually unusable in its raw state, into dozens of petroleum products. Marketing is the wholesale and retail distribution of those products to businesses, governments, and everyday consumers.
On the refining side, you have massive industrial complexes that process hundreds of thousands of barrels of crude per day. On the marketing side, you have everything from the fuel trucks that supply gas stations to the contracts that deliver jet fuel to airports and natural gas to power plants. Refineries tend to be located near population centers specifically to keep distribution costs down.
How Refining Works
Refining starts with fractional distillation. Crude oil is heated in a tall column, and different components separate based on their boiling points. Lighter products like gasoline vapor rise to the top, heavier liquids called gas oils collect in the middle, and the heaviest fractions settle at the bottom.
That initial separation is just the starting point. Refineries use a range of secondary processes to reshape those raw fractions into higher-value products:
- Cracking uses heat, pressure, and catalysts to break heavy hydrocarbon molecules into lighter ones, producing more gasoline and diesel from each barrel of crude.
- Reforming converts naphtha, a relatively low-value light fraction, into high-octane gasoline components using heat, moderate pressure, and catalysts.
- Hydrotreating strips out unwanted elements like sulfur and nitrogen. Under current EPA Tier 3 standards, finished gasoline must contain no more than 10 parts per million of sulfur on an annual average basis.
- Alkylation combines smaller molecules into higher-octane blending components, a process that became especially important after the U.S. banned lead in gasoline in 1996.
The specific mix of processes a refinery uses depends on what it’s trying to produce. A refinery optimized for gasoline will run its units differently than one focused on diesel or jet fuel.
Products That Come Out of Refineries
A single barrel of crude oil yields a surprisingly wide range of products. The high-volume fuels get the most attention: motor gasoline, diesel, heating oil, and kerosene-type jet fuel. But refineries also produce asphalt for roads, lubricants for engines, waxes for packaging, and petrochemical feedstocks that serve as the raw materials for plastics, fertilizers, and synthetic fibers.
That petrochemical connection is a major part of the downstream story. Feedstocks from refining account for roughly 12% of global oil demand, and that share is growing as worldwide demand for plastics and other chemical products increases. Refineries produce compounds like ethane and naphtha, which are then “steam cracked” at petrochemical plants to create ethylene and propylene, the building blocks for everything from plastic bottles to medical devices.
Distribution and Logistics
Getting finished products from refineries to end users involves a layered transportation network. Pipelines carry large volumes of gasoline, diesel, and jet fuel to regional distribution terminals. From there, tanker trucks make the final deliveries to gas stations, airports, and industrial customers. Rail and marine transport fill in the gaps, particularly for moving products to areas not served by pipelines or for exporting fuels overseas.
Operational decisions at this stage include scheduling truck and tanker dispatches, managing loading and unloading at terminals, and monitoring product quality throughout the supply chain. A batch of gasoline that picks up contamination in transit can fail to meet sulfur or octane specifications, so quality control doesn’t end at the refinery gate.
How Downstream Companies Make Money
Downstream profitability is measured by the “crack spread,” which is simply the difference between what a refinery pays for crude oil and what it can sell its finished products for. A wider spread means fatter margins. In mid-2025, diesel crack spreads at New York Harbor reached 85 cents per gallon, nearly double the level from a year earlier. Gasoline crack spreads in early September 2025 were more than double their year-ago level.
These margins fluctuate constantly based on crude oil prices, seasonal fuel demand, refinery outages, and regulatory costs. A refinery can be highly profitable one quarter and squeezed the next if crude prices spike faster than product prices adjust. This volatility is why some of the largest downstream companies operate at enormous scale to spread risk across multiple refineries and product lines.
Major Downstream Companies
The world’s largest refiners by capacity are dominated by state-owned and multinational giants. China Petrochemical Corp (Sinopec) leads with nearly 6 million barrels per day of refining capacity. China National Petroleum Corp follows at about 4.9 million barrels per day. ExxonMobil ranks third at roughly 4.7 million barrels per day. Saudi Aramco and Valero Energy round out the top five.
Some of these companies are integrated, meaning they operate across upstream, midstream, and downstream. Others, like Valero, are pure-play downstream companies focused entirely on refining and marketing. On the retail side, gasoline service stations handle the bulk of consumer sales, while oil companies sell directly to factories, power plants, and transportation operators. Natural gas sales split roughly evenly among industrial users, electric utilities, and residential and commercial heating customers.
Regulatory Pressures on Refining
Environmental regulations shape nearly every aspect of downstream operations. The EPA’s Tier 3 standards, for instance, cap gasoline sulfur at 10 ppm on an annual average and 80 ppm on a per-gallon maximum. Meeting those limits requires refineries to invest heavily in hydrotreating equipment, which adds to operating costs but significantly reduces tailpipe emissions of sulfur dioxide and particulate matter.
Clean fuel standards continue to tighten globally, pushing refineries to spend more on processing while simultaneously preparing for a longer-term shift in energy demand. Many downstream operators are now evaluating decarbonization strategies for their own facilities. The main options include capturing carbon emissions from hydrogen production (known as blue hydrogen), producing hydrogen using renewable electricity (green hydrogen), and electrifying the steam generation that refineries rely on. Carnegie Mellon University research found that, at current energy prices, natural gas with carbon capture remains more economical than electrification-based alternatives. Electrification only becomes competitive if electricity prices drop by more than 60% or very strict emissions regulations are imposed.
Downstream vs. Upstream and Midstream
The simplest way to remember the three sectors: upstream finds and extracts oil and gas from underground reservoirs. Midstream transports raw crude and natural gas through pipelines and on tanker ships. Downstream transforms those raw materials into products and delivers them to the people and businesses that use them. Some companies span all three sectors, but each has distinct economics, risks, and skill sets. Downstream margins depend on the spread between crude costs and product prices, while upstream profits hinge on the price of crude itself. A drop in crude prices can actually help downstream margins if product prices hold steady.