IVZ - General Discussion, page-963

"Kiwi, for the non-geo’s on here are you saying that The mud weight is a negative to the drill program and ultimately the production aspect of the project? Or are you saying that this type of scenario is common and just dealt with in another manner? TIA"

What I was trying to get across was the usefulness of looking at other rift basins in East Africa to identify pre-drill the issues we saw in M-1 and the sidetrack. I don't think the hole issues are related to geology or tectonic stress...I think our problems are largely due to running too high a mud weight which is creating differential sticking as well as fractures in the well bore. The degradation of the well bore is being made worse by mechanical "hammering" of the bore by the rotating drill string.

With mud weight you basically need to arrive at a target weight that is high enough to keep formation fluids from ingressing into the wellbore but at the same time not so high that you force drilling fluid liquid and solid components into the formation. The latter can result in differential sticking and what is known as formation damage. Formation damage can come back and bite you when you do a flow test or put the well on production. If mud weight is so high that you are at or over your fracture gradient then you will induce fracturing in the bore hole wall.....in an extreme situation this can result in mud losses and dangerous well control scenarios.