Why did it take so long to develop Rosebank?

Why did it take so long to develop Rosebank?

Deepwater Blackrock well finds oil west of Shetland

Deepwater Blackrock well finds oil west of Shetland

Fig. 2. Schematic geological cross-section through the Faroe–Shetland...

Fig. 2. Schematic geological cross-section through the Faroe–Shetland...