The Environment Agency has published an application to revise the rules for a well test at Rathlin Energy’s oil and gas site at West Newton in East Yorkshire.
This follows the discovery of oil in the site’s second well, West Newton-A2, during a test in August 2019. The company had expected to find mainly gas. The test, due to last up to six weeks, was suspended soon after it started.
The company is now seeking variations to the site’s environmental permit. These comprise:
- Pump to mechanically lift oil from the well
- Different flare
- Use of a hydrogen sulphide (H2S) scavenger in stored oil
- Permission for one vent per storage tank
The changes were described by both Rathlin Energy and the Environment Agency (EA) as “minor technical”.
The EA said it was not inviting comments on the application “as there are no requirements to consult on minor technical variations”.
“the proposed changes do not have the potential for significant negative effects on humans or the environment”.
If approved, the changes would update permits issued in April 2014 and August 2019.
Rathlin Energy has said the oil at West Newton-A is in the Kirkham Abbey reservoir under a gas cap.
“It is best practice to fully investigate and produce the oil section within a reservoir prior to any exploitation of the gas which may provide pressure within the reservoir to enable the oil to be lifted to surface.”
The company said existing techniques to lift the oil, including the use of nitrogen, could not “maximise the recovery of liquids” from the Kirkham Abbey reservoir.
It said mechanical lifting using a beam (nodding donkey) or rod pump were considered the “best engineered solution”.
This would not introduce new waste streams or change the volume or chemical composition of waste, the application said. It would also not add “any substantial risk of fugitive emissions”.
Nitrogen lifting would be maintained as a contingency, the company said.
Rathlin said a smaller flare – the CEB350 – was now proposed to burn any gas emitted with the oil during the flow test.
This was designed for smaller volumes of gas, the company said. The application said the flare had “very short, non-luminous blue flames” and would prevent smoke, soot and odour.
It operated at the same temperature as the originally specified flare and pollutant releases were “unlikely to pose any substantial risk to, or have any significant influence on, the attainment of environmental standards”, Rathlin added.
The company said gas samples taken from the first attempt at the well test last year had been contaminated with what it called “reaction gas” from the acid wash and squeeze and a nitrogen lift.
Rathlin said new modelling was not needed:
“we believe it is not appropriate to model the air dispersion using the recently analysed gas samples from the WNA-2 test and to continue to rely upon the originally proposed gas composition as a representative model of the gas composition over a longer term flow period.”
The well clean-up and test are estimated by Rathlin to burn more than 3,500 tonnes of gas.
The application said a hydrogen sulphide scavenger would be used in crude oil storage tanks to remove any trace of H2S in the oil.
The company was also seeking to change the requirement to vent all the storage thanks through one vent point.
“We have found that this limits the type of storage tanks that are possible to use. Without the need to comingle the vent points, this would enable different types of storage tanks to be used giving more flexibility”.