You pump the cement from inside & squeeze it into the annulus to hold the CSG.
Volume of cement pumped depends on the casing depth, in this case we have a 8.5" Open hole & a 7" Casing, which means the Annulus is 1.5". The 7" casing has been run from 9743' (last casing point) to current depth of 15397'. Differnce of 5654'
To hold this 5654' of 7" casing, u would need x bbls of cement. After this one has to wait for this cement to set. There is some cement left inside which is drilled out before you start drilling fresh hole.
What's happened here is the cement must have been soft & they kept running the drill pipes only to realise that its stuck for good.
Cheers
Hope this explains yr query.
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