From my model, 10% gives $488 mill12.5% gives $311 mill15% gives...

From my model, 10% gives $488 mill

12.5% gives $311 mill

15% gives $200 million

I think 15% per year is excessive.

The reason why I used 5% was because after factoring in the decrease in the real value of money due to inflation, that is what the project is going to return in real dollars ($1.2 billion) to the company

I understand though that risk needs to be factored into the equation also especially given it is an oil/gas project as they rarely register as low risk.