mauritanian drilling update almost unchanged, page-8

who knows why its deviating - could be hardness of rock or not.

From what I understand (but in no way can say if it is the case here) that there is a method of casing where it the casing does not extend all the way up the well bore - but attached or hung from the bottom of the previous string. (Forgive me if I have terminology wrong)

This method has some advantages (speed, less steel used, and leaves open some drilling options) but can cause deviation.

There is a an article somewhere on the web about it - but cant be bothered tracking down.

Reaming as Yacheng has noted might be because of underpressured mud and pressured formations squeezing into the well bore. Slow drilling can also be result of soft formations clogging up the bit.

I think a hundred possibilities exist as to why, but one thing for sure its going to take longer than expected.

Someone was keen to put some pocket money on the options at market price. Hope this bodes well.

good luck to holders.