RE: Dry?30 Jan 2021 18:23
Extract from Weald Action Group
"Acidisation is a stimulation technique, used to release oil and gas from unyielding rock such as sandstone and limestone. It involves injecting solutions of acids and other chemicals into the ground, either to clean the well, or to create passageways through the rock along which oil or gas can flow.
It is used where companies are targeting oil in limestone and sandstone rock formations – such as in the Weald, as well as at West Newton, Wressle & Ellesmere Port.
In a report written for UK Oil & Gas Plc in 2016, consultants EY confirmed: “Kimmeridge Limestone Oil likely requires “stimulation’ to flow to the surface at commercial rates. The primary stimulation method for wells in limestone rock formations is acidizing.”
Acidisation and fracking: what’s the difference?
Acidisation and fracking – short for high-volume hydraulic fracturing – are both stimulation techniques designed to release oil or gas tightly trapped inside the pores of rocks. While fracking is used to crack open shale, acidising is used to dissolve passageways through limestone or sandstone.
The Infrastructure Act 2015 introduced a new definition of fracking as involving the injection of more than 1,000 cubic metres of fluid per stage or more than 10,000 cubic metres in total. Under current UK law, fracking can only take place at below 1,000 metres depth. The type of oil exploration we see in the Weald uses lower volumes of water, so is not counted as fracking and is not subject to the fracking regulations or the current (probably short-term) moratorium.
Yet acidisation requires similar techniques to fracking, including the drilling of long horizontal laterals, and a densely-spaced pattern of wells, and many of the same impacts (see below).
In other parts of the world, such as the US, fracking means hydraulic fracturing AND acidising. And the fact that acidisation is not defined as fracking in the UK means that operators are not subject to the same regulations – and acidisation is not covered by the moratorium on fracking announced in November 2019."