Onshore oil and gas sector guidance

12. Sub-surface information for hydraulic fracturing

When you need to provide sub-surface information and the type of information you need to provide.

12.1 When you need to provide sub-surface information

You must provide sub-surface information if you will be carrying out hydraulic fracturing. This is because the Environment Agency needs to know where:

  • the fractures will go – so they can understand any risk to groundwater
  • waste fluid will be left behind - so they can define the extent of the mining waste facility

For all other oil and gas applications, the Environment Agency will assess on a case-by-case basis what information you will need to provide. This will depend on the activities you intend to carry out and their associated risks.

You should send the Environment Agency your sub-surface information at the permit application stage, as part of your waste management plan.

12. 2 Type of sub-surface information to provide

You should include the following information.

Map of faults

You must provide a map showing faults near the well and along the well path. Also provide a summary assessment of faulting and formation stresses in the area and of the risk that the operations could reactivate existing faults.

Operations, activities and techniques

Provide a summary of your planned operations, including the:

  • techniques you will use
  • location of monitoring points
  • stages
  • pumping pressures
  • volumes and the predicted extent of each proposed fracturing event

Describe the processes and procedures that you will put in place during hydraulic fracturing to:

  • identify where the fractures are within the target formation
  • ensure that they are not near the permitted boundary

If the fractures were to extend beyond the permit boundary, describe the steps that you would take to:

  • assess and if necessary mitigate the effect
  • limit further propagation outside the target rocks

Provide a comparison of your proposed activity with any previous operations and their relationship to any historical seismicity.

Seismicity information

Provide information on the local background seismicity and an assessment of the risk of induced seismicity.

Also provide information about the proposed measures you will use to:

  • mitigate the risk of inducing an earthquake
  • monitor local seismicity during the operations

If there is a seismic event greater than agreed in your Oil and Gas Authority approved Hydraulic Fracturing Plan, you must suspend activities. You will not be able to resume fracturing until the Environment Agency has approved evidence that the wells are not damaged and the groundwater remains protected. This will be a condition in your permit.

12.3 Sub-surface information and low volume hydraulic fracturing

If you are planning to carry out low volume hydraulic fracturing in a conventional hydrocarbon formation, you should contact the Environment Agency as soon as possible. This is to make sure that you apply for the most appropriate permits.

The Environment Agency will also advise you on how much sub-surface information you may need to provide and what that information should include.