RE: Lincoln30 Jun 2018 13:47
Ricfle,
"Was not Halifax exploration well failure to flow, also due to formation damage?"
You are correct. And as an anecdotal aside, I speculated that that ('formation damage') was what had occured at the time of Halifax (early last year) and was castigated by various posters here for using 'scaremongering' language!
"I think it is safe to say that "Hurricanes exploration wells do not flow well" and we know the reasons for this. We can also say that Hurricane's production wells flow prodigiously."
Also correct, but maybe not everyone understands these reasons and it may be worth expanding on them a bit (once again) in layman's terms.
Firstly, 'formation damage' in the context means (in a 'conventional' reservoir) that the pore spaces of the rock surrounding the wellbore have become clogged up and the oil contained within can't flow, or its flow is hindered. It's the same in FB formations, except that the rock is not porous, so this 'plugging' takes place in the fissures through which the oil flows.
Secondly, this 'plugging' is restricted to an area immediately surrounding the particular wellbore, and doesn't extend far from it, so 'formation damage' occuring around one well doesn't have an effect on the rest of the reservoir.
Thirdly, and most importantly, the relative lack of Hurricane's success in flow testing their exploration wells is in no way their 'fault', and nor does it imply any sort of technical incompetence on their part.
The thing being, Hurricane is caught in a bind in such circumstances, one which is none of their doing. There are certain regulations in place regarding drilling of 'exploration' wells, and they're mandatory. And one regulation involves 'pressure overbalance'. Without going into this too much (lack of space), to achieve the mandatory 'overbalance' (for safety purposes), a heavy 'drilling mud' must be used. And in a normally or low-pressured well (like those on Rona), this heavy fluid can cause ground-up rock particles from the drilling not to be swept to surface, but instead to clog up the flow-channels.
Once the exploration discovery has been made, any subsequent well is termed 'appraisal', and the regulations regarding mud density are less strict, because the field's pressure characteristics are now known. So lighter fluids can be used, and the chances of clogging or 'formation damage' easily mitigated.
This is why Dr T mentioned the possibility of drilling a new Halifax well, because it would be 'appraisal'. So, in fact, would be a re-entry of the original well, but it's simply that a new well might be cheaper than trying to clean out the 'gunk' that's plugged the fissures in the old one.
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