A water well is created by drilling a hole in the ground and letting it fill with water.  A natural gas well needs to drill further, into the underground rock itself.  That means these wells are deeper and therefore more dangerous to construct.

Natural gas wells are holes drilled into the bedrock to reach sources of natural gas.  A license is needed to operate an existing private natural gas well in Ontario.  Licensing promotes safer operation, improves public safety and protects the environment.

All oil and natural gas exploration and production in Ontario are regulated by the Oil, Gas, and Salt Resources Act (OGSRA). Changes to the Act in 1997 require that all oil and gas wells be licensed by the Ministry of Natural Resources (MNR).  In addition to commercially owned and operated oil and gas wells, this licensing requirement applies to privately owned natural gas wells.

Under the Oil, Gas and Salt Resources Act, 1997, tough standards ensure that oil and gas wells are developed and decommissioned under strict guidelines.  Many earlier gas and oil wells had inferior or improper linings, with the earliest wells being lined with wood.  To err on the side of caution, landowners must assume that any unused wells found on their property have not been properly sealed or permanently plugged.


Ministry of Agriculture, Food and Rural Affairs

Locating Existing Water, Gas or Oil Wells


Private gas well licences

How to apply for a licence for the operation of an existing private gas well.


Policy for licensing private gas wells

The criteria under which operating, pre-existing private gas wells can become licensed by the Ministry of Natural Resources and Forestry under the Oil, Gas and Salt Resources Act.


Private gas wells: qualified person’s manual

Manual designed for qualified persons for evaluating private gas wells under the Ontario government private gas well incentive program.


Locating Old Gas Wells – What to Look For

Older oil and gas wells generally have largely uncemented steel liners whereas newer wells usually have steel casings that are cemented full length.  Very old oil wells may have wooden liners.

Key Ways to Look for Wells

Start by searching documents that may identify the location of wells.  Look for:

  • water well records (Ministry of the Environment)
  • oil and gas well records (Ontario Oil, Gas & Salt Resources Library, London, Ontario)
  • building permits, old land deeds, property surveys and land transfer documents (municipal and township offices)
  • old fire insurance plans

How to Systematically Search for Potential Well Sites

After reviewing physical records or maps, conduct a systematic land search for potential well sites.

  • Carefully walk the entire property, looking for any areas that may be an old farmstead site. Watch carefully for unplugged wells.
  • Uncultivated areas (grassy and treed areas) within actively cropped fields may offer some clues, especially for locating old oil and gas wells.
  • Look for any metal or wooden debris indicating a well may be near.
  • Look for pipe or casing material or covers that may conceal a well. Again, take care in moving any material that may be covering an old well as the ground nearby or the old well top may be unstable and collapse.

Examine surfaced well pipes.

Only landowners in Lambton, Kent, Essex, Elgin, Oxford, Norfolk, Haldimand, Brant, Welland and Niagara need to find oil and gas wells on their property.  To a lesser extent Huron, Middlesex, Perth, Wentworth, Halton, Wellington, Grey and Bruce counties also had some development of varying degrees.

Oil and gas fields are typically developed as a cluster of wells and are joined by infrastructure to efficiently remove and store product from the deposit on the same site.  Signs of past producing sites and unused oil and gas wells include:

  • pipes joining wells to holding tanks, oil spills (early oil production)
  • storage tanks sunken and above ground, wooden and metal construction
  • pumping systems i.e. jack pumps
  • well access trails or roads, cement or stone drilling pads
  • old drilling equipment, bits, cable, steel rods and metal casings
  • electrical boxes, utility poles and remnants of electrical, motors or engines required to power pumps

These wells could be located anywhere on the property.  Long established neighbours or local community members are invaluable sources of information, as well as historic aerial photos.  Look for changes in vegetation development or sites and access trails disturbed by previous oil and gas activity.  Soils at these locations may be compacted so vegetation is stunted and sparse.  Many old oil pumps and storage tanks commonly leak oil on site.  Sites absent of vegetation or with tar-like deposits are good indicators.  Old oil and gas wells may also leak methane, or salty or sulphurous waters that kill vegetation.

Unused oil or gas well and remnants

As a best management practice identify on a sketch or map all suspect sites, blast holes, cisterns, and exploration boreholes for mineral, geothermal, geological, or geophysical purposes.  Mark all confirmed or highly suspect well locations on maps.

Other Resources to Identify the Locations of Old Unused Wells

One difficulty in locating some wells is that over time:

  • they may have back-filled (improperly plugged)
  • the casing may have been cut off below the ground surface or
  • the wellhead may be buried, leaving no visible evidence at the surface

In these situations wells can often be located efficiently using non-invasive geophysical survey methods.  Geologists commonly use these surveys to locate metallic minerals and oil and gas deposits buried beneath the earth’s surface.  Geophysical surveys allow interpretation of various formations, objects and processes in the ground without costly excavation.  Three surveys considered practical for locating well-type structures are: electromagnetic, magnetic and ground penetrating radar.

Steel casings can be detected using an electromagnetic (EM) instrument (buried metal detector) or a magnetometer (which measures the strength of the earth’s naturally occurring magnetic field).  Magnetic surveys are more susceptible to interference from metal objects such as vehicles and metal clad buildings than EM surveys.  To find buried wells with little metal, a Ground Penetrating Radar (GPR) survey may be used.  Due to cost considerations, a GPR survey is most effective when focused on a few key areas of a site.

EM61 Well survey image. (Source: Conestoga-Rovers & Associates)

Reporting Previously Unknown Well locations

Report any well discovered that has no previous record either within the Ministry of the Environment or the Ministry of Natural Resources.  This will provide valuable information to future generations of land users and developers.  There may be multiple old wells on a single property; do not stop looking after the first one is located!

For sealing requirements, contact the Ministry of Natural Resources for oil and gas wells licensing and plugging standards.

Well Quick Reference Check Off

High Potential for a Well?

  • Farm properties that include multiple farmsteads, abandoned land or structures and uncultivated sites.
  • Farm located in a former or current oil/gas producing area.
  • Areas of different or stunted vegetation, compacted trails/sites, oil residue, abandoned drilling pads.

Unused Well Investigation

  • Searched for records of oil, gas and water well locations (MNR & MOE).
  • Searched for old irrigation permits, building permits, site surveys and plans.
  • Thorough ground investigation of abandoned fields, old farmsteads, former livestock feeding sites and fence lines.
  • Checked around debris piles, old foundations, and partially buried pipes, stone, brick, wood, clay tiles and well casings.
  • Farm infrastructure examined including:
    • windmill sites
    • holding tanks
    • farm structures
    • out buildings
    • outdoor electrical boxes
    • abandoned utility poles
    • abandoned well pumps, hand pumps and motors
  • Have other aids including aerial photos or geo­physical surveys been utilized?
  • Deep pits or unusual depressions with seepage and aquatic vegetation, stunted, dead or no vegetation areas.