BP Azerbaijan vice-president for Shah Deniz, Rob Kelly, said the purpose of the well was to prove the remaining reserves on the field and to pave the way for the development's second phase.
Stage two will be similar to the first stage, which aimed to produce around 8 billion cubic metres per year.
The SDX-4 well will have the additional purpose of probing the deeper horizons on Shah Deniz which, so far, have remained unexplored.
