Hi fishfinder. Formation damage often happens as a result of increasing the weight of the drilling mud (measured in pounds per gallon) to control high pressures encountered while drilling. The problem is that the operator will put safety of crew and equipment first and well integrity second for obvious reasons. To stabilise the well with high mud weight means the fluid pressure in the uncased well bore must at least match that of whatever is in the formation and trying to enter the well bore (gas, oil or water). The problem is that the mud can invade the pore spaces of the reservoir in the immediate vicinity of the well bore and cause certain clay-type minerals, if they're present, to swell and block off the pores preventing flow of anything into the well. If they know anything about the makeup of the reservoir in advance, they can make up special non-invasive muds but these are usually a lot more expensive. There are several other ways a well can be damaged also, but once damaged the more common remedy is to plug back the hole and drill a sidetrack into a fresh part of the reservoir, trying to avoid making the same mistake twice. Damage is normally limited to the vicinity of the well so re-drilling to a bottom-hole location 50m or more away is often enough to get fresh reservoir. They normally only find out about well damage when trying to flow test a reservoir that they already know exists and is full of gas/oil.
For what it's worth, I understand NEG to be pretty savvy operators and they wouldn't have been interested in partnering PRE if they didn't think this prospect had good potential. California is also their stamping ground.
I've learnt all this from years of reading drilling reports and postings by experienced oilies here and elsewhere. I have some geo knowledge but nothing first-hand around the drilling process. Hope this helps, cheers.
PRE Price at posting:
0.0¢ Sentiment: Hold Disclosure: Held
