Oil extraction depends on what type of oil you’re talking about. Crude oil is pulled from underground rock formations using a combination of natural pressure, injected fluids, and sometimes advanced chemistry. Edible oils like olive or canola oil are squeezed or chemically dissolved out of seeds and nuts. Both processes have multiple stages designed to get as much oil out as possible, and the methods vary widely based on depth, location, and the type of material being tapped.
How Crude Oil Reaches the Surface
Crude oil doesn’t just sit in an underground lake waiting to be scooped up. It’s trapped in the tiny pores of rock formations, sometimes thousands of feet below the surface. Getting it out starts with drilling a well into the reservoir, but the real work is creating enough force to push oil through rock and up to the surface.
The first stage, called primary recovery, relies entirely on natural energy already present in the reservoir. Several forces can drive oil upward: dissolved gases expanding as pressure drops, a cap of compressed gas pushing down on the oil, natural water flowing in from surrounding rock, or simple gravity in tilted formations. When a well is first drilled, the pressure difference between the reservoir and the wellbore is often enough to force oil to the surface on its own. This is the classic image of a “gusher,” though modern wells are carefully controlled to prevent that.
Primary recovery is the least efficient stage. It typically pulls out only 5 to 15 percent of the oil that’s actually in the reservoir. A huge amount stays locked in the rock, trapped by the same capillary forces that make a paper towel hold water. Even in the best-case scenarios with strong natural water drive, 10 to 40 percent of the oil remains stuck in the pore spaces.
Boosting Pressure With Water and Gas
Once natural pressure drops too low to push oil to the surface, operators move to secondary recovery. The idea is straightforward: inject something into the reservoir to restore pressure and physically push the remaining oil toward production wells.
The two most common approaches are waterflooding and gas flooding. In a waterflood, water is pumped down injection wells drilled around the production well. The water spreads through the rock formation, displacing oil and driving it toward the wellbore where it can be collected. Gas flooding works the same way but uses natural gas, carbon dioxide, or air instead of water. The injected fluid acts like a piston moving through the rock, sweeping oil ahead of it.
Together, primary and secondary recovery typically yield 20 to 40 percent of the original oil in the reservoir. That means even after two full stages of extraction, more than half the oil is still down there. This is why a third stage exists.
Enhanced Recovery for Stubborn Reservoirs
Enhanced oil recovery, sometimes called tertiary recovery, uses more advanced techniques to coax out oil that water and gas alone can’t reach. These methods change the physical properties of the oil itself or alter the chemistry of the reservoir to make extraction easier.
Thermal methods are common for heavy, thick crude oil. Injecting steam into the reservoir heats the oil, making it thinner and easier to flow. Chemical injection uses specialized fluids, like detergent-like compounds, that reduce the surface tension holding oil in the rock pores. Gas injection at this stage often involves carbon dioxide that actually dissolves into the oil, lowering its viscosity and helping it slip through tight spaces.
Enhanced recovery can extend a field’s productive life significantly, but it’s expensive. Operators use it when oil prices are high enough to justify the cost of the additional infrastructure and materials.
Extracting Oil From Shale Rock
Conventional reservoirs have enough natural permeability for oil to flow through the rock. Shale formations don’t. The rock is so tight that oil can’t move through it without help, which is where hydraulic fracturing comes in.
The process starts with drilling a vertical well hundreds to thousands of feet down, then turning the drill sideways to bore horizontally through the oil-bearing shale layer. This horizontal section can extend thousands of feet, maximizing contact with the rock. Once the well is drilled, large quantities of fluid, mostly water mixed with sand and chemical additives, are pumped down the wellbore at extremely high pressure. This pressure cracks the shale, creating a network of fractures radiating out from the well.
The sand (or ceramic pellets) in the fluid serves a critical purpose: it wedges into the new fractures and holds them open after the pressure is released. These propped-open cracks give oil a pathway to flow from the rock into the wellbore. Once pumping stops, the formation’s internal pressure pushes the fracturing fluid back to the surface, followed by oil and gas. This combination of horizontal drilling and hydraulic fracturing unlocked vast oil reserves in formations like the Permian Basin and Bakken Shale that were previously considered unrecoverable.
Offshore and Deepwater Systems
Extracting oil from beneath the ocean floor adds layers of complexity. In shallow water, operators build fixed platforms that sit on the seabed and function much like onshore drilling rigs. Deepwater production, where the ocean may be thousands of feet deep, requires a different approach entirely.
Deepwater wells are drilled by mobile rigs, but instead of building a permanent platform over every well, operators install equipment directly on the seafloor. A subsea “Christmas tree,” a large assembly of valves and gauges, sits on top of each wellhead to control the flow of oil. Multiple wells can be connected to a central manifold on the ocean floor, which collects oil from several wells and routes it through a single pipeline.
The oil travels from the seafloor to the surface through vertical pipes called risers, which connect to a floating production vessel or a nearby fixed platform. Some deepwater fields pipe oil directly to shore through undersea pipelines without any surface facility at all. The complexity of these systems, which include umbilical lines carrying power and control signals to seafloor equipment, makes deepwater extraction among the most technically demanding and expensive forms of oil production.
How Edible Oils Are Extracted
Plant-based oils follow a completely different process, though the goal is the same: separate oil from the solid material holding it. The two main methods are mechanical pressing and solvent extraction, and most large-scale operations use both.
Mechanical Pressing
An expeller press, also called a screw press, forces seeds or nuts through a narrow cavity using intense friction and continuous pressure. As the material is squeezed, oil separates from the solid meal and drains away for collection. No external heat is added, but the friction itself generates temperatures between 140 and 210°F. Cold-pressed oils use gentler equipment that keeps temperatures below 122°F, preserving more of the oil’s natural flavor and nutrients. The tradeoff is that cold pressing leaves more oil behind in the leftover meal.
Solvent Extraction
After pressing, the leftover press cake still contains usable oil. In industrial processing, this cake is broken into flakes and mixed with hexane, a petroleum-based solvent that dissolves the remaining oil. The slurry is heated so the hexane evaporates and can be collected for reuse. The oil-hexane mixture is then distilled to separate the two. By combining mechanical pressing with solvent extraction, producers recover nearly all the available oil, leaving less than 1 percent in the spent meal.
The crude oil that comes from either method isn’t ready for the shelf yet. It goes through bleaching with special clay to remove pigments and impurities, then deodorizing to strip out unwanted flavors and smells. Only after these refining steps is the oil packaged and sold.