Actually they are of similar depths and would use the same rigs. GBP are ahead of things where they have a CPR completed and have an estimate of reserves in place 3.66bln barrels
Here is an interesting read on AEC, who I know are in talks assessing Namibian assets currently and in this link show how they don't need 3D before drilling
There strategy is to accumulate assets and farm down to between 5% to 25%, with an example they are currently farming down from 90%
Also explains the deal they are farming down, they are planning to drill next year with just 2D seismic and gain data from the well