Fossil fuels are taken from the Earth mainly in two ways: coal is mined, while crude oil and natural gas are recovered through wells. Shallow coal seams can be exposed with surface mining, while deeper seams require underground mines. Oil and gas wells may be vertical, directional, or horizontal. Hydraulic fracturing is sometimes used after drilling to open pathways in tight rock. Oil sands are a special case: shallow deposits can be mined, while deeper bitumen is heated underground and pumped to the surface.
The exact method depends on the fuel’s physical form, the depth of the deposit, the permeability and pressure of the surrounding rock, and whether the resource is on land or offshore. Extraction is also only the first stage. Coal may be cleaned, crude oil must be refined, and raw natural gas often requires processing before it can be used.
Key Takeaways
- Coal is extracted by mining. Surface mines expose shallow seams, while underground mines reach deeper coal through shafts, slopes, and tunnels.
- Oil and natural gas are usually extracted through wells. Reservoir pressure may move the hydrocarbons toward the well, or pumps and other recovery techniques may be needed.
- Horizontal drilling and fracking are different processes. Horizontal drilling changes the direction of a well; hydraulic fracturing creates pathways in low-permeability rock after the well is drilled.
- Bitumen requires specialized extraction. Shallow oil sands can be surface-mined, while deeper deposits commonly use steam-assisted in-situ recovery.
- Extraction and refining are not the same. Extraction removes a resource from the ground. Processing, upgrading, and refining prepare it for transport or use.
Fossil Fuel Extraction at a Glance
| Fossil fuel | Where it is found | Main extraction methods | What usually happens next |
|---|---|---|---|
| Coal | Solid seams in sedimentary rock | Surface mining or underground mining | Crushing, screening, optional washing, and transport |
| Crude oil | Porous reservoirs, tight rock, offshore formations, or oil sands | Conventional wells, horizontal wells, hydraulic fracturing, offshore drilling, enhanced recovery, surface mining, or in-situ bitumen recovery | Separation from water and gas, transport, upgrading when needed, and refining |
| Natural gas | Conventional reservoirs, shale and tight rock, coalbeds, or oil reservoirs | Vertical, directional, or horizontal wells; hydraulic fracturing for many tight formations | Gathering, removal of water and impurities, separation of natural gas liquids, and pipeline transport |
What Are Fossil Fuels?
Fossil fuels are nonrenewable energy resources that formed as organic material was buried and altered by heat and pressure over millions of years. Coal formed mainly from ancient plant matter. Most petroleum and natural gas formed from microorganisms and other organic material deposited in marine or lake environments—not from dinosaurs.
The three main fossil fuels have different physical properties:
- Coal is a carbon-rich solid rock found in seams.
- Crude oil is a liquid mixture of hydrocarbons found in porous rock or low-permeability formations.
- Natural gas is a mixture of gases composed primarily of methane. See why natural gas is classified as a fossil fuel.
- Bitumen is an exceptionally heavy, viscous form of petroleum found in oil sands. It may not flow without heat or dilution.
These differences explain why there is no single fossil-fuel extraction process. A solid coal seam is excavated. Mobile oil or gas may flow toward a well. Tight rock may need to be fractured, while viscous bitumen may need to be heated before it can move.
How Companies Find and Develop Fossil Fuel Deposits
Mining and drilling begin only after geologists identify formations that may contain a usable resource. The details vary by country and project, but development generally follows five stages.
- Geological screening: Geologists study rock layers, existing borehole records, surface features, and the history of a sedimentary basin.
- Geophysical surveys: Seismic waves, gravity measurements, magnetic surveys, and other methods help map underground structures. Seismic data can identify promising formations, but it cannot prove that a commercially recoverable deposit exists.
- Exploration: Companies drill exploratory wells for oil and gas or take cores and samples for coal and oil-sands projects. These tests reveal the depth, thickness, pressure, composition, and likely productivity of the deposit.
- Development and production: If the resource is technically, economically, and legally viable, the operator builds production wells, mine workings, roads, pipelines, processing facilities, and water-management systems.
- Closure and reclamation: When production ends, wells must be plugged, facilities removed, and disturbed land managed according to the applicable permits and regulations. Long-term monitoring may still be needed.
For oil and natural gas, the U.S. Energy Information Administration explains that exploratory drilling is needed to confirm what seismic surveys suggest. Offshore projects follow the same basic logic but require ships, mobile drilling units, fixed or floating production systems, and subsea infrastructure.
How Is Coal Extracted?
Coal is a solid rock, so it is removed by mining rather than pumped through a conventional oil or gas well. The two broad methods are surface mining and underground mining.
Surface Coal Mining
Surface mining is used when a coal seam is shallow enough to reach economically from above. In the United States, the EIA uses approximately 200 feet as a general dividing point, although the practical cutoff varies with geology, regulations, land conditions, and mining costs.
Operators first clear the site and remove the soil and rock above the coal, known as overburden. Excavators, draglines, loaders, and haul trucks then remove the exposed coal. Surface methods include strip mining, open-pit mining, contour mining, and mountaintop removal.
After mining, an operator may reshape the land, replace stored soil, manage drainage, and replant vegetation. Reclamation can reduce long-term damage, but it does not instantly recreate the original soils, streams, forests, or habitats.
Underground Coal Mining
Underground mining is used when the seam is too deep for practical surface excavation. Workers and machinery enter through vertical shafts, sloped passages, or horizontal openings. Cutting machines break coal from the seam, and conveyors, rail systems, or vehicles carry it out of the mine.
Underground mines usually disturb less land at the surface than a large open pit, but they create different risks. Mine roofs require support, ventilation is needed to manage dust and methane, and old workings can contribute to subsidence or acidic mine drainage.
What Happens to Coal After Mining?
Raw coal may go to a preparation plant, where it is crushed, screened, and sometimes washed to remove rock, dirt, ash-forming material, and some sulfur-bearing minerals. The coal is then transported by conveyor, truck, rail, barge, or ship to a power plant, industrial facility, export terminal, or other customer.
How Is Oil Extracted?
Most crude oil is extracted through wells drilled into oil-bearing formations. The well may be vertical, directional, or horizontal. The recovery method depends on the rock’s permeability, reservoir pressure, oil viscosity, depth, and location.
Conventional Oil Wells
In a conventional reservoir, oil and gas have moved into porous rock beneath a less-permeable layer that traps them. A production well creates a path between the reservoir and the surface.
During primary recovery, natural reservoir pressure and gravity may push oil toward the well. As pressure declines, operators can use artificial-lift equipment such as pumps or gas lift. The pumpjack commonly seen in oil fields powers a downhole pump rather than physically scooping oil from the ground.
Operators may then use secondary recovery, commonly injecting water or gas to maintain pressure and move additional oil toward production wells. Enhanced oil recovery can use steam, carbon dioxide, other gases, or chemicals to change how the remaining oil flows through the reservoir.
Tight Oil, Horizontal Drilling, and Fracking
Tight oil is held in rock with very small pores and low permeability. A vertical well may not expose enough of the formation to produce oil economically, so the operator can steer the well horizontally through the oil-bearing layer.
After the well is drilled and prepared, hydraulic fracturing may be used to create small fractures in the target rock. A fluid consisting mainly of water, proppant such as sand, and chemical additives is injected under pressure. The proppant holds the new fractures open so oil and gas can move toward the well.
Horizontal drilling describes the direction of the well. Hydraulic fracturing describes a stimulation treatment. They are often used together, but they are not the same process.
Offshore Oil Extraction
Offshore oil is extracted from rock below the seabed. Companies first use geological data and marine seismic surveys to identify possible traps. An exploratory well is then drilled from a mobile platform or drillship. A seismic target does not become a proven oil field until drilling confirms the resource.
If the discovery is commercially viable and approved, development wells may be connected to a fixed platform, a floating production facility, or equipment installed on the seafloor. Oil and gas move through risers and pipelines to processing facilities, storage systems, tankers, or shore.
Offshore production uses the same basic reservoir principles as onshore production, but deeper water, waves, storms, subsea pressure, corrosion, remote emergency response, and marine ecosystems make the engineering and risk management more complex.
Oil Sands and Bitumen Extraction
Oil sands contain bitumen mixed with sand, clay, water, and other minerals. Bitumen is petroleum, but it is far more viscous than conventional crude oil. It should not be treated as evidence that all oil begins as a solid.
In Alberta, deposits less than about 75 metres below the surface can be mined with large shovels and trucks. The mined material is crushed and mixed with hot water and other process materials so the bitumen can be separated. Sand, water, clay, and fine particles left by the process become tailings that require long-term management.
Deeper deposits are generally recovered in situ, meaning in place. Two important thermal methods are:
- Steam-assisted gravity drainage (SAGD): Two horizontal wells are drilled, one above the other. Steam enters the upper well, heats the bitumen, and allows it to drain toward the lower production well.
- Cyclic steam stimulation (CSS): Steam is injected into a well, the heated reservoir is allowed to soak, and the same well is then used to produce the softened bitumen. The cycle can be repeated.
The recovered bitumen may be diluted for pipeline transport or upgraded into a lighter synthetic crude before refining. For a fuller assessment of the land, water, energy, and economic tradeoffs, see the pros and cons of oil sands.
How Is Natural Gas Extracted?
Natural gas can occur in conventional reservoirs, tight sandstone, shale, coal seams, offshore formations, or alongside crude oil. Although natural gas is mostly methane, raw gas from a well can also contain water vapor, carbon dioxide, hydrogen sulfide, nitrogen, helium, and natural gas liquids.
Conventional Natural Gas Wells
In a conventional gas reservoir, gas occupies pore spaces or fractures in rock and can often move toward a well because of reservoir pressure. The well may be vertical or directional, depending on the position and shape of the reservoir.
Gas reaching the surface enters gathering lines. Associated gas produced with crude oil is separated from the oil at the production site or a nearby facility.
Shale Gas and Hydraulic Fracturing
Shale and other tight formations have low permeability, so gas does not move through them easily. Operators commonly drill a vertical section, turn the well gradually, and continue horizontally through the target formation. Hydraulic fracturing then creates flow paths between the rock and the well.
Fracking is not limited to natural gas. It can also be used to produce tight oil. The benefits, limitations, and risks depend on the geology, water supply, well construction, chemical handling, wastewater management, regulation, and proximity to communities and ecosystems. See the pros and cons of fracking for a broader comparison.
Natural Gas Processing
Gas leaving a well is not always ready for a transmission pipeline. At a processing plant, operators can remove water, hydrogen sulfide, carbon dioxide, and other impurities. Ethane, propane, butanes, and heavier natural gas liquids may also be separated and sold as distinct products.
The resulting pipeline-quality gas is compressed and sent through transmission networks. An odorant is normally added farther downstream so leaks can be detected by smell.
What Happens After Fossil Fuels Are Extracted?
Extraction ends when the raw resource has been removed from the ground. Several additional stages may follow:
- Coal may be crushed, sized, washed, blended, and transported to a power plant or industrial customer.
- Crude oil is separated from produced water and gas, stabilized, and sent to a refinery. Refining separates and converts crude oil into products such as gasoline, diesel, jet fuel, lubricants, asphalt, and petrochemical feedstocks.
- Bitumen may be diluted for transport or upgraded into synthetic crude before entering a refinery.
- Natural gas may be dehydrated, treated to remove contaminants, and processed to separate natural gas liquids before entering a pipeline.
This distinction matters because mining, drilling, processing, transport, refining, and combustion have different environmental footprints and are regulated through different systems.
Environmental Effects of Fossil Fuel Extraction
No extraction method is impact-free. The severity and likelihood of harm depend on the resource, geology, project design, operating practices, local ecosystems, enforcement, and what happens after the site closes. The extraction impacts below should also be considered alongside the broader advantages and disadvantages of fossil fuels.
Land and Habitat Disturbance
Surface mines remove vegetation, soil, and rock across large areas. Oil and gas fields can fragment habitats through well pads, roads, pipelines, compressor stations, power lines, and water infrastructure. Underground coal mining has a smaller surface footprint than a comparable open pit, but subsidence can affect land and structures above old workings.
Water Use and Water Quality
Mining can alter drainage and expose sulfur-bearing minerals that create acidic runoff. Oil and gas production brings saline water and other naturally occurring substances to the surface. Oil-sands mining produces tailings, while thermal bitumen recovery uses water to generate steam.
The U.S. Environmental Protection Agency found scientific evidence that activities in the hydraulic-fracturing water cycle can affect drinking-water resources under some circumstances. Higher-risk situations include spills, inadequate well integrity, poorly managed wastewater, unlined storage pits, and water withdrawals in areas with limited supply. EPA also concluded that available data did not support a reliable estimate of how frequently such impacts occur nationwide.
A detailed discussion is available in our guide to the environmental consequences of fracking.
Air Pollution, Methane, and Climate
Engines, processing equipment, flaring, venting, and leaks can release carbon dioxide, methane, nitrogen oxides, volatile organic compounds, and other pollutants. Methane is the primary component of natural gas and can escape during production, processing, transmission, storage, and distribution.
The greatest climate impact of most fossil fuels occurs when they are burned. The United Nations identifies coal, oil, and gas as the largest contributors to global climate change, accounting for more than three-quarters of global greenhouse-gas emissions.
Spills, Waste, and Tailings
Oil spills can occur at wells, storage tanks, pipelines, terminals, and offshore facilities. Drilling produces rock cuttings and fluids that require management. Coal mines generate waste rock, and oil-sands mining creates large quantities of water, sand, clay, and fine particles that must be contained and reclaimed.
Produced water from oil and gas wells can contain salts, hydrocarbons, metals, treatment chemicals, and naturally occurring radioactive materials. Its composition varies widely, so describing all oil-and-gas wastewater as equally toxic or radioactive would be inaccurate.
Induced Earthquakes
Hydraulic fracturing can trigger earthquakes in some geological settings, but it is not responsible for most induced earthquakes associated with oil and gas development in the central United States. According to the U.S. Geological Survey, deep disposal of large volumes of oil-and-gas wastewater is the primary cause of that regional increase in seismicity.
Wastewater disposal and hydraulic fracturing are separate activities. Not every disposal well causes an earthquake, and not every fractured well produces felt seismicity. Risk depends on injection volume, pressure, faults, subsurface pathways, and local geology.
Can Fossil Fuel Extraction Be Made Less Damaging?
Fossil fuels remain nonrenewable even when extraction is well managed. Operational controls can reduce particular harms, but “lower impact” does not mean impact-free or renewable.
Measures that can reduce risk include:
- Avoiding sensitive habitats, drinking-water sources, unstable geology, and culturally important sites where development would create unacceptable risks.
- Using fewer well pads through directional drilling where doing so genuinely reduces total land disturbance.
- Maintaining well casing, cement, pressure controls, pipelines, tanks, and offshore safety systems.
- Monitoring and repairing methane leaks rather than routinely venting usable gas.
- Reducing freshwater withdrawals, reusing suitable water, preventing spills, and treating or securely disposing of wastewater.
- Managing tailings, waste rock, erosion, and drainage throughout the project rather than waiting until closure.
- Plugging inactive wells, removing equipment, restoring drainage, replacing suitable soil, and monitoring reclaimed land.
- Publishing environmental data and enforcing permits with independent inspections and meaningful penalties.
The Bottom Line
How are fossil fuels taken from the Earth? Coal is mined, while most oil and natural gas are extracted through drilled wells. Surface and underground mines reach coal seams. Conventional wells rely on reservoir pressure and pumps. Horizontal drilling and hydraulic fracturing help release oil and gas from tight rock. Offshore systems reach formations below the seabed, and oil sands may be mined or heated underground.
Understanding these distinctions makes it easier to evaluate each method’s land, water, air, climate, and waste impacts. Reducing demand through practical energy conservation techniques and expanding energy sources with lower greenhouse-gas emissions can reduce the need for additional fossil-fuel extraction.
Frequently Asked Questions
What are the two main ways fossil fuels are extracted?
The two broad methods are mining and drilling. Coal is normally removed through surface or underground mines, while crude oil and natural gas are usually produced through wells drilled into resource-bearing rock.
Is fracking the same as drilling?
No. Drilling creates the well, and horizontal drilling describes the direction of that well. Hydraulic fracturing is a later stimulation process that injects fluid under pressure to create flow paths in low-permeability rock.
How is oil brought to the surface?
Oil may move toward a well under natural reservoir pressure, but pumps or gas lift are often needed as pressure declines. Operators can also inject water, gas, steam, carbon dioxide, or chemicals to recover additional oil.
What happens after fossil fuels are extracted?
Coal may be cleaned and sized, crude oil is transported to a refinery, and raw natural gas is often processed to remove water and impurities. Bitumen may also be diluted or upgraded before refining.
Does fracking cause earthquakes?
Hydraulic fracturing can trigger earthquakes in some locations, but most induced earthquakes associated with oil and gas operations in the central United States have been linked to deep wastewater disposal. The two activities are separate.
Is fossil fuel extraction sustainable?
Fossil fuels are nonrenewable because they form far more slowly than people consume them. Better regulations and operating practices can reduce specific impacts, but they do not make the resources renewable or eliminate the effects of extraction and combustion.