The estimate that I saw was 2000-3300 well sites for Lancashire, multiple bore holes for each site.
The more that I examine the geology the more unlikely it seems that they will be able to sink wells safely as there are many many faults that are known about, never mind the hidden ones. They drilled through one fault and did not even know about it until the earth tremor crushed their borehole. Every fault is a potential leakage point for the chemicals used to reach the aquifers.