A new consultation has opened on expansion plans at the Horse Hill oil site in Surrey.
The operator, Horse Hill Development Ltd (HHDL), is seeking changes to the environmental permit to drill and test four new oil wells, drill a water reinjection well and produce and store oil at the site.
These operations received planning permission last month from Surrey County Council. But they also need consent under the environmental permit, issued by the Environment Agency.
The consultation runs until 25 November 2019.
HHDL said it was seeking environmental permit consent for the following activities:
- Construct five new drilling cellars
- Drill four new hydrocarbon wells (making a total of six production wells at the site)
- Drill one new produced water reinjection well
- Carry out 90-day extended well tests on each of the four new oil production wells
- Carry out well maintenance workovers and operations, including acid wash and/or hot oil treatment
- Drill well side-tracks, if necessary
- Produce oil from the wells and separate produced oil, gas and water
- Install oil processing, storage and tanker loading facilities
- Store produced oil and water in separate vented tanks
- Reinject formation water
- Discharge surface rain water from the well site extension into Spencer’s Gill watercourse
- Remove all surface production equipment, followed by plugging and abandonment of six production wells and one water reinjection well
- Remove and dispose of surface bunding and stone surfacing, followed by regrading of all soils
A letter submitted with the application said any gas produced during extended well tests would be burned in an enclosed flare. The letter, from the air quality consultancy Socotec UK Ltd, said the volume would not exceed 10 tonnes per day. Additional flaring from the four new wells would “of course give rise to additional releases of greenhouse gases”, the letter said. The maximum disposal rate for a total of 540 days of flaring was the equivalent to 15,017 tonnes of carbon dioxide, it added.
HHDL also said it planned to apply for an environmental permit to operate generators to produce electricity from gas. But this was not included in the current proposed variations, it said
Why the permit changes are needed
Crude oil storage
The Horse Hill site currently has a standard rules permit for oil storage (EPR/SP3339YS). The expansion of the site means it cannot meet conditions of distance from a water course and the limit of 500 tonnes storage capacity. The operator is applying for a bespoke permit for storage and handling of crude oil with a tank storage of 500 tonnes or more
The current permit (EPR/BB3300XG) provides for drilling and testing the HH-1 and HH-2 boreholes. HHDL is seeking to vary this permit to add four more production boreholes (HH-3, HH-4., HH-5 and HH-6) and drill a single reinjection borehole. The wells will be drilled on the existing site. But HHDL intends to extend the site to accommodate production equipment so the permitted boundary will increase.
The current permit (EPR/BB3691NN) allows for discharge of surface water from the well site (outlet 1). The variation seeks to add two additional outlets. The extended production area will need to dispose of surface water through an oil-water separator into a tributary of Spencer’s Gill. A further outlet (outlet 3) will be required for injection of produced water and collected surface water from containment bunds. This will be used to support production of oil from the Portland formation, the application said.
The Environment Agency (EA), which will decide on the permit changes, said people could comment on the application in the following ways:
- By post: Environment Agency Permitting and Support Centre, Regulated Industry Team, Quadrant 2, 99 Parkway Avenue, Sheffield S9 4WF
- By email: PSCpublicresponse@environment-agency.gov.uk
The EA said it would consider comments on:
- Relevant environmental regulatory requirements and technical standards
- Information on local population and sensitive sites
- Whether the right process or technology was proposed
- Whether the impact on land around the site was acceptable
- What pollution control or abatement may be required
- Impact of noise and odour from the site
- Permit conditions
- Information that the EA was unaware of
- Corrections to wrong information in the application