Please do not compare California gas with Banda. It is not worth even a small fraction of your numbers.
Gas developments are very expensive, and as Mauritania does not have any infrastructure, value capture from the gas development will be very very difficult. With little domestic demand and an uncertain immediate export demand, a rough assessment of the gas resource at Banda would be zero.
In the current market, equity investors are paying little or nothing for static or stranded gas. The best example of this is the current position of the PNG Group, where the gas is not valued at all by the main brokers, despite an active marketing campaign.
US gas markets are very deep, with heaps of nearby infrastructure and plenty of deep markets. Recent US gas prices are of the order of US$3/GJ and above, in comparison with domestic Australian wellhead prices of It is very difficult to generalise on the net worth of a gas volume.