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The truth is that the the " Unprecedented " Retention Lease Agreement sets out a 5 year work program (4 years in reality given the development report is due 30 days from start of the 5th year) inclusive of all development studies.
Fact is that the Retention Agreement requires that the parties commit to development at the earliest occasion (or potentially lose it) removing Shells discretion to simply use Crux as a Prelude backfill some 10 years hence.
IMHO Crux in its current size probably doesn't justify a stand alone FLNG operation given Prelude under development however should Auriga drilling be successful then Crux project with Caelum upside will in fact be larger than Prelude/Concerto - no way that Shell could convince NOPTA to allow a deferral of development for a further 10 years.
If Auriga is successful we will not even have to wait 4 years to know what is happening re Crux development - we will know next June based on the framework of the Retention Lease.
If Auriga and Caelum are dry - backfill option is probable