A key document needed to allow small-scale fracking at Wressle in north Lincolnshire has not yet been approved.
In response to a freedom of information request, the Environment Agency said the hydraulic fracturing plan (HFP) for Wressle was still “in draft”.
The site operator, Egdon Resources, must have approval of the HFP if it is to go ahead with proposals for a proppant squeeze. This is an operation that involves injecting liquid and proppant under pressure into the target formation to improve oil flows.
The Environment Agency (EA) regards proppant squeeze as a form of low volume fracking because the injection pressure is high enough to fracture rocks.
The HFP outlines what an operator would do to minimise the risks of earth tremors from fracking. It also states how the hydraulic fracturing process would be monitored and controlled.
It must be approved independently by both the Environment Agency (EA) and the Oil & Gas Authority. The Health and Safety Executive also has a chance to comment.
Egdon Resources said yesterday it had begun work to reperforate the section of the Wressle well through the Ashover Grit formation. If this does not improve flows sufficiently, the company will seek to carry out the proppant squeeze.
Last week, the EA refused a freedom of information request for a copy of the Wressle HFP. It said:
“Currently, we are unable to provide you with the Wressle 1 Hydraulic Fracturing Plan as it is in draft.
“If it is approved a copy of the plan will be available on our Public Register for you to view.”
The EA said a public authority could refuse to disclose information which was “still in the course of completion”, or from unfinished documents. It said:
“Disclosure of a draft would be misleading and create an inaccurate representation.
“The effort involved in correcting a misleading impression would be so great that it would hinder the Environment Agency from completing the work of which the incomplete information is part.”
“First proppant squeeze”
The Wressle proppant squeeze would be the first carried out in the UK on a deviated well under a town, according to another freedom of information response.
Local campaigners sought information about the operation because they were concerned that the injection would be directly beneath the town of Broughton.
The EA responded:
“Since the EA began regulating oil and gas sites in England there have been no permits granted for the scenario described.
“Only one operator has a permit that includes a proppant squeeze activity, this activity has not taken place as yet, the well is vertical and does not extend beneath a town / village.”
The environmental permit for Wressle has already revealed that Egdon Resources plans a single fracture treatment of 150m3 of slurry comprising gelled liquid and ceramic beads.
The slurry would be injected at 9,000psi [pounds per square inch], above formation fracture pressure, for 1-2 hours. According to the permit, the slurry would be forced 40m sideways into the formation and 20m above and below perforations in the wellbore. An estimated 50%-70% of proppant fluid would be retained within the formation.
The extra information required in an HFP is set out in Onshore oil and gas sector guidance.
This says companies should provide geological studies to assess the risk of seismic activity, and to prevent any hydraulic fracturing operations taking place near geological faults.
EA says it needs to know where:
- fractures will go – so that it can understand any risk to groundwater
- waste fluid will be left behind – so that it can define the extent of the mining waste facility
The guidance said the OGA must also be satisfied that controls were in place to minimise the risk of a seismic event or any disturbance to those living and working nearby.
HFPs for small-scale fracking usually require less information than those for high volume hydraulic fracturing. A standard HFP would include:
- Map showing faults near the well and along the well path
- Summary assessment of faulting and formation stresses in the area and the risk that operations could reactivate existing faults
- Summary of planned operations including techniques, location of monitoring points, stages, pumping pressures, volumes and predicted extent of each proposed fracturing event
- Processes and procedures to identify where fractures are within the target formation and not near permitted boundary
- Steps to be taken to mitigate effect of fractures that go beyond the permit boundary and limit further propagation outside the target rocks
- Local background seismicity and assessment of risk of induced seismicity
- Proposed measures to mitigate the risk of inducing seismicity