eli5 Why do North American oil wells have shorter lifecycles than wells in the middle east?


eli5 Why do North American oil wells have shorter lifecycles than wells in the middle east?

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North America started oil production in the early 1900s. The biggest oil reservoirs are the first to be extracted. So the remaining oil reservoirs now are small and hard to reach. The oil production in the middle east started a bit in 1930 but did not really got going until the 50s and 60s. And then in 1970 the OPEC was created which artificially limits the oil production to keep the oil price up. The US is not part of OPEC and is therefore not limiting the production.

Could it be the general size of the oil field, the rate of withdrawal etc compared to those in the ME….rather than conditions/performance…or, it is the conditions hot/cold….I’ve been no help really.

A key measure for oil wells is something called “permeability”, basically how easy it is to move fluid through the rock. Contrary to popular cartoons, oil reservoirs aren’t big “caves” of oil underground, they’re spongy rock with oil in the holes. The more permeable the rock, the bigger an area can be “drained” by a single well.

Middle East oil reservoirs are ludicrously permeable…you basically stick a glorified straw in the ground and oil comes out, and it keeps coming out because that one well can drain a really large area.

Oil reservoirs everywhere else, including North America, tend to be less permeable. You need more wells to drain the same volume of reservoir and each well runs “dry” (can’t get reasonable flow out anymore) faster.

And then there’s fracking. North America has a ton of reservoirs that have very low natural permeability, so low that they can’t economically produce on their own. You have to frac them (artificially crack the rock and stuff it full of high permeability sand) to get anything at all. This works really well, but only as far as you can frac the rock. As a result, these run dry even faster and you need to drill bazillions of them to drain the same reservoir.

I guess I should clarify. I read somewhere that North American oil wells have a massive loss of production after about a year, something like 80% on average. Meanwhile typical wells in the Middle East retain significant output even decades into use.

Is there a geological reason? Do American companies just suck it dry super quick where Saudi wells are on top oceans of oil?