RE: prospects5 Feb 2020 20:50
ronok,
I must admit that immediately after sending that post, I realised that (1) using a car braking system to illustrate some hydraulic principles was not very appropriate, (2) the way I worded it wasn't quite right and that someone would immediately ask about conservation of energy (yourself, as it happens!) and (3) a car braking system (a tiny input providing a big output) is quite the reverse of the Lancaster reservoir, which also isn't a closed system now it's been drilled into. The wells can be thought of as a tiny (really tiny) 'leak' in the system...
It also occurred to me that my post was somewhat patronising, so I apologise for that. I wasn't trying to impluy you're some sort of ignoramus, and your own reply shows you certainly aren't.
But it's all good O/T stuff!
Let's get the brakes thing and conservation of energy out of the way, first, though. No, the control input energy provided by the driver's foot on the brake pedal is only a tiny, tiny proportion of the energy expended in slowing the car. Try standing in fronto of a moving car and stopping it with your foot. You'll end up in hospital! No instead, you have to look at the entire 'moving car system' holistically. And it's a very high energy system indeed, it possesses far more energy than any human being does, by vast orders of magnitude. And where does the energy come from? The fuel in the tank, of course. Not from the person doing the driving.
Anyway, we could rabbit on about some basic physics 'til the cows come home. What about the reservoir?
OK, you're right. A small amount of aquifer water will move into space previously occupied by oil, of course. But one or two things must be remembered. 1 Oil (and associated gas in solution) is compressible: the aquifer 'pressure drive' water is not. 2 Oil is far less dense than the water, and so needs far less 'encouragement' to flow to surface than the drawdown required to get the water to move up. 3 (and this is important), the aquifer may be assumed to have an areal extent far greater then the reservoir. It may be tens or even hundreds of miles in extent. Dspp seems to be forgetting to mention this.
And this is my argument with him. Let's look at water coning in a 'conventional' field. It usually only starts to happen in a significant way once the field goes into full development production, and even then may take years. No two fields are alike, or rarely. The other thing I alluded to earlier, and that's the question of scale, (in size terms). The two EPS wells represent just a tiny pressure 'leak' in the system. Like a pinhole in your car tyre. And unlike most leaks, they don't get bigger the more of the air (or oil) escapes. So yes, eventually your tyre will start going flat, but not immediately.
Bottom line is yes, as you've remarked as a layman, there's a heck of a lot of energy involved in that oil and gas coming to the surface, overcoming gravity, friction, etc. But there's a lot more where that came fr
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