Ann: Strong Gas Shows in Multiple Upper & Lower Angwa Reservoirs, page-58

The Mkanga FM is pretty deep....I dont think its marked on the seismic sections Ive seen to date.

A number of issues may prevent drilling to that sort of depth:

1) Well control factors - ie insufficient kick tolerance.
2) Rig capacity and amount of drill pipe on hand
3) Risks associated with having a long open hole section
4) Usually when you get to depths of around 4000 porosity and permeabilty start to deteriorate due to effects of compaction and other processes. Not always the case though as Strike Energy proved with their Erregulla drilling in N Perth Basin.