The Oloibiri Field cost $640 million to develop, including all Exploration and Appraisal expenditure and pre-license costs. It is estimated that the field had, at inception the following reserves:

- 240 million barrels of Proved Reserves

- 320 million barrels of Proved and Probable Reserves

- Production up to and including 31-12-2019 was 20 million barrels

Required:

1. Calculate the DD&A rate per barrel on Unit of Production (UoP) basis. Use Proved Reserves as your reserve definition.
2. Calculate the DD&A charge up to 31-12-2019.
3. Calculate the DD&A rate per barrel on Unit of Production (UoP) basis. Use Proved plus Probable Reserves as your reserve definition.
4. Calculate the DD&A charge up to 31-12-2020.