drilled to 2850 only- industry answer

This is the most logical reason they stopped drilling at 2850 metres.

“Information from a geologist/petroleum, geopressure engineer with 40 years’ experience in the petroleum exploration industry.

-The main reason they would have stopped drilling is that they have a lost circulation zone encountered at the top of the reef.

As you drill deeper, the pressure In the well bore increases everywhere due to the increasing drilling mud column height.

You thus run the very grave risk of fracturing the reef lost circulation zone/formation (known as exceeding the formation fracture gradient)
and losing your mud column which in this case is holding back hydrocarbons in the reefal formation.

Should you lose circulation and your mud column, the hydrocarbons will flow out of the reefal formation into the well bore and you will have a ‘kick’.

If the ‘kick’ is controlled by a method such as the ‘drillers method’, then in this situation you would stop drilling.

If the kick cannot be controlled, and is contained by the blowout ppreventors within the well bore, It will be an underground blowout and you have ’lost’ the wellbore.

If the ‘kick’ is not controlled by the rig blow out preventors, you will have a blowout at the surface which could in the worst case destroy the rig and personnel
and you have lost the well bore, now the least of your concerns.

So ‘kicks’ are to be avoided at all costs.

You normally only drill deeper for geological information like source rock when you have a dry hole and the drilling conditions are safe
and in real life you have not exceeded your drilling budget.”