umiat oil field update no 4, page-58

szaba,

That could do it, I guess. I'm not entirely convinced the perforation charges would melt enough water to completely bung up the entire well, but for argument's sake let's say that could be the reason.

But from what you say, this was all known decades ago, so why did LNC try a conventional case and perf job? Even WITHOUT those extra complications from the permafrost, it's not exactly a novel concept that if your reservoir quality is poor (which from those chips it seems to be) you don't case and perf!

Offset well studies are fundamental to a drilling engineer's job - when they drill a well in a new area they always research what was done on previous wells in the area to find out what works and what doesn't.

So they must have known all this, yet they still chose to do it. Either they were trying to confirm it doesn't work, or there was some colossal management failure.

But my personal suspicion is they never intended this one to flow - hence why they planned the horizontal. It was a science well, I think they wanted to gather their data and then they were done with it, so they figured they might as well try a case and perf.

This may be because they drilled the well so heavily overbalanced that a barefoot completion wouldn't have worked, the formation would have been too damaged with drilling mud. So perhaps they cased and perfed in the hope that the perforations would penetrate through the invaded zone and into fresh rock.

Some out-of-the-box thinking that didn't work. But it's no big deal, they already have the horizontal planned and that was obviously the great hope.

fidosnos,

The guy interviewed stated that the core was dripping oil. Could it be the oil based mud they used rather than reservoir oil?

I don't know because I didn't see it, but I think they should be able to tell the difference between refined mud and crude, but the mud would definitely cause the sample to fluoresce.

If the formation is so tight with poor permeability do you think a horizontal well wouldn't be much better for flow?

An underbalanced barefoot horizontal should hopefully be okay. It's the overbalanced drilling and then the cementing that do the damage. The underbalanced drilling and cementing should cause the oil to flow, then the horizontal is used to increase your flow rate by increasing your apparent formation thickness and also increasing your chances of intercepting fractures.

But you're right, if the well won't flow at all then a horizontal isn't likely to help you. Horizontals are generally expected to roughly triple the flow rate of a vertical well, but three times zero is still zero!

How about serious and extensive fracturing as a means to let loose the oil?

I don't think they would have much luck fraccing at such a shallow depth. They're only at about 170m there from what I understand. But if it was deeper fraccing would be a very viable technology.

Doen't drilling generate plenty of heatand pressure around the core as well as compress/seal the region around the drill bit essentially melting any ice all the way and sort of cauterize as it travelled down hole?

Yes it generates plenty of heat, but most of the water created by the drill bit should be removed by the circulation of the drilling mud. At any rate, this well did flow to surface after perforating which happened long after drilling so obviously drilling heat or freezing due to drilling is not the issue here.

And finally, how the heck do they know there is a billion+ barrels of oil when even the drilling shows ambiguity?

Well, they don't. That's just an estimate based on the limited currently available info. It could be much more, or much less. Specifically in this case I don't believe there has been any serious production at Umiat so while the OIP estimate may be reasonably accurate (from wireline logs, seismic, core etc), the EUR estimate (ie how much oil they can actually extract) will still be subject to a very large uncertainty.

In this case the total recovery is probably somewhere between 5% and 40% of the OIP. That's a factor of 8 difference. Throw in the uncertainty in OIP too and you can see the uncertainty estimate is huge. That billion barrels could be 100 million or it could be 2 billion.