Finding out whether your land sits above natural gas starts with a combination of geological clues, water testing, public records, and professional surveys. No single sign gives you a definitive answer, but several indicators taken together can paint a reliable picture of what’s beneath the surface.
Check the Geology of Your Area
Natural gas forms in specific types of rock, and knowing what lies beneath your property is the most fundamental step. Gas-rich shale is the source rock for most natural gas deposits. In conventional formations, gas migrates upward from shale into sandstone, where it becomes trapped by an impermeable layer above it. If your land sits over shale or sandstone formations, the geological conditions for gas are at least plausible.
Other gas-bearing formations include tight sand deposits, where gas gets trapped in low-permeability sandstone, and coal beds, which generate their own methane during the natural transformation of organic material into coal. Salt domes can also act as trapping structures. Your state’s geological survey office publishes maps showing these underground formations, and many are available online. Start by looking up your county on your state geological survey’s website to see what rock types are mapped beneath your property.
Test Your Well Water for Methane
If you have a private water well, it can serve as a direct sampling point for dissolved gas. Methane from underground deposits sometimes migrates into groundwater, and a simple lab test can measure the concentration in your water.
The U.S. Department of the Interior considers methane levels below 10 milligrams per liter (mg/L) generally safe. Levels between 10 and 28 mg/L warrant regular monitoring, and concentrations above 28 mg/L call for immediate action to reduce the level. High methane in well water doesn’t automatically mean you’re sitting on a commercially viable deposit, but it does confirm that gas is present underground in your area. Contact a certified water testing laboratory in your state to request a dissolved gas analysis. The test typically costs between $100 and $300.
Look for Surface Clues
Natural gas is odorless and colorless in its raw state. The rotten-egg smell people associate with gas comes from a chemical added by utility companies for leak detection, so you won’t smell anything from a natural seep. That said, gas seeps do leave visible traces on the land.
Persistent bubbling in ponds, streams, or marshy areas on your property can indicate methane rising from below. Patches of dead or stunted vegetation surrounded by otherwise healthy growth sometimes mark spots where gas displaces oxygen in the soil. In some cases, the soil itself feels warm or has a slightly oily sheen where water pools.
Microbes in the soil also respond to gas. Bacteria that feed on methane, called methanotrophs, become more abundant in soils with higher concentrations of gas seeping up from below. While you can’t see these bacteria with the naked eye, researchers have found that shifts in soil microbial communities reliably correlate with underground gas movement. If a soil scientist or environmental consultant takes samples from your property, elevated populations of methane-eating bacteria can confirm that gas is migrating through the ground.
Search Historical Drilling Records
One of the most practical steps is checking whether anyone has already drilled on or near your land. Every state maintains records of oil and gas wells, including active, abandoned, and orphaned wells. The U.S. Geological Survey hosts a nationwide dataset of documented unplugged orphaned wells, compiled from individual state agencies. Your state’s oil and gas regulatory agency will have its own database, often with an interactive map you can search by address or coordinates.
California, for example, publishes an Oil and Gas Well Finder that lets you view every documented well in the state, including details like well status, depth, spud date, and whether the well was abandoned or is still active. Texas, Pennsylvania, Ohio, and other major gas-producing states offer similar tools. If historical wells exist on or near your property, that’s strong evidence of subsurface gas potential, even if those wells are no longer producing. Old, plugged wells also tell you something about the formation type and depth where gas was found.
Hire a Professional Assessment
If surface clues and records suggest potential, the next step is bringing in professionals. A geologist can evaluate your property’s subsurface structure using existing seismic data and geological maps. For more precise information, a seismic survey sends sound waves into the ground and measures how they bounce back, revealing the shape and depth of rock layers below. This is the same technique energy companies use before committing to drill.
Soil gas surveys are another option. A technician inserts probes into the ground at multiple points across your property and measures the concentration of methane and other hydrocarbons in the soil. Elevated readings, especially when they form a pattern across the landscape, strongly suggest gas migration from a deeper source. These surveys are less expensive than seismic testing and can be completed in a day or two for a typical rural property.
Verify Your Mineral Rights
Even if gas exists under your land, you may not own it. In the United States, mineral rights can be separated from surface rights, a process called severance. This means a previous owner may have sold or transferred the rights to the oil, gas, and minerals beneath the surface while keeping (or selling) the land itself. The U.S. is one of the few countries where individuals can own mineral rights at all, which makes the ownership question especially important here.
Start by reviewing your property deed or title. It will specify whether mineral rights are included or have been severed. If the language is unclear, visit your county clerk’s office, where historical land records can reveal if and when rights were separated. For properties with a long chain of ownership, this research can get complicated. Professionals known as landmen specialize in tracing mineral rights through decades of transactions, though their services can be costly. If you discover that your mineral rights are intact, you’re in a position to lease or develop them. If they’ve been severed, the mineral rights holder has the legal authority to access the subsurface resources, sometimes even without your consent as the surface owner.
Safety Considerations
Natural gas seeps are not just a potential resource. They’re a potential hazard. Methane is highly flammable, and gas accumulating in enclosed spaces like basements, wellhouses, or outbuildings can reach explosive concentrations. If you suspect active gas seepage, avoid open flames and ensure good ventilation in any structures near the suspected area.
Gas seeps can also affect soil quality and groundwater. Contaminated water associated with natural gas deposits may require treatment before it’s safe for drinking or irrigation. If you’re testing your well water and find elevated methane, address the safety issue first and the resource question second. A local environmental health office or your state’s department of environmental quality can guide you through testing and mitigation options specific to your area.