Potential for Mukuyu-1's Results to be Above Market Expectations, page-237

I think the porosity/permeability is intergranular and not fracture related.

Usually where you get significant fractures and a balanced or close to balanced well you'll often get what is known as ballooning. Basically what happens is the equivalent circulating density (ECD) of the mud exceeds the fracture point of the formation and mud is injected into the fractures. Once circulation stops the ECD drops and some of the mud plus entrained gas is expelled back into the well bore. This can in turn cause well flows at connections and sharp gas mud gas peaks.

Note that you don't need exceedingly high permeability to get differential sticking going on......it can happen when you have a high over balance and moderate permeability or alternately it can happen when there is a low to moderate overbalance but high permeability.