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为什么我们分开考虑静水压力和地面压力吗?

在石油地质,为什么我们分开考虑静水压力和地面压力吗?肯定在任何时候的压力,是否液体或岩石,在深度是相等的重量流体和岩石覆盖它吗?因此为什么不是液体和固体的压力等于在一个特定的深度?

回答

我花了一段时间才得到它(和我不是一个地质学家或石油工程师或任何东西,只是有人谁知道基本的物理学和已读地质教材),但我想我明白了埃里克的回答是:它是基于浮力。考虑一个列透水岩石和土壤的曝气带饱和带。(我要讲水,但是它也适用于油或空气或其他流体密度小于当地的岩石或土壤)。如果任何重量从土壤/摇滚推饱和带的水,它就会把水的方式,提高水位,同时降低一些岩石和土壤。这是由于岩石和土壤的密度比水,所以重力势能减小当岩石/土壤和推动同等体积的水。水的不透水层上面可以支持一些石头的重量,因为浮力这将创建不能把水从防渗层。如果一个洞是在说不透水层,流离失所的水可以通过那个洞允许支持摇滚解决有点低(承压井如何工作)。——如果水支持一些石头的重量,这部分重量(这一部分静岩压力)必须支持的压力,是本地(大约)静水(等于各个方向),因为这是静止的液体可以施加压力的唯一途径。这意味着水压力也可以推动,这似乎应该当地层倾斜或弯曲,透水层对表面开放的一部分,其余的则由不透水过于床上,在一个典型的含水层,和它:当你移动侧表面(常数引力势(锅。能量÷质量)/重力势)水的静水压力必须保持不变; otherwise, the water would flow sideways to equalize it. (Actually, this isn't entirely true, as can be determined from my geology textbook, which notes that "pores ... provide resistance to flow", related to permeability of the rock/soil and viscosity of the fluid I guess, and that "pressure is lost through fractures (leaks)", presumably in the "imperable" layers, but it's a good starting approximation.) As you move down through the water, the pressure goes up according to how much more weight (weight of the water and possibly a bit of the rock) the water at that point needs to support. (Reverse as you go up.) Now, remember that the water at the top of the water table in the area with a zone of aeration above it, and atmosphere above that, cannot support any lithostatic pressure. As you go straight down from here, let's assume only the weight of the water above being supported by the water, not any rock/soil. (I think that's true, but I'm not sure. In any case, it doesn't significantly affect my point if not.) As you move sideways from a point below the permable zone of aeration to a point below an impermable bed, the height of water above you has to drop from the height of the water table to the height of the bottom of the impermable bed (whenever this gets lower than the water table under air). More importantly, this generally means there is less weight of (contiguous) water pushing down on the water where you are. (I'm just noticing that, since much or most of the volume underground is rock/soil, volume and therefore weight of water in a column is only proportional to height in rock/soil of constant porosity, but that approximation basically works within a single permable bed.) However, the hydrostatic pressure must stay (approximately) the same. The only way to accomplish this is for the water to push up some of the rock and support enough of the lithostatic pressure to (approximately) equal the weight of water lost. (Actually resistance to flow and leaks mean the pressure goes slightly down as you move further sideways away from an area below air, which is why the "artesian-pressure surface"/"potentiometric surface" above an aquifer slopes down as you move away from the "recharge area" rather than being flat.) --- I imagine a little extra complexity is added when your dealing with gasses rather than liquids (so the density of the fluid is highly dependent on the hydrostatic pressure it's under), when fluids are in motion rather than stationary, or when you consider the permeability of rocks quantitatively rather than as just "permeable" and "impermeable".

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\ begingroup美元我刚刚意识到湿实占用更多的体积比干土,我认为消除水从土壤和岩石,甚至从未限制与不透水层会导致沉降(在墨西哥城,大部分的城市是建立在过去是一个湖床湖的水被抽出之前)。这意味着对我来说,水必须是支持的一些地面压力在潮湿土壤,反驳我的浮力的论点。也许这是有关水和颗粒之间的范德华力,也就是。,“抗流”有关?也许我真的错了吗? \ endgroup美元
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2021年7月8日23:46
\ begingroup美元也许我应该多考虑到了我的浮力的概念。岩石是在水中浮力密度比水,所以水压力不能单独实际上推石头,但水压力仍然高附近的岩石颗粒的底部比顶部,所以它可能仍然施加一个向上的力,它将删除一些负载下面的谷物。这减少地面压力可能导致谷物扩大或减少趋势来解决低,包紧。 \ endgroup美元
- - - - - -H . H。
2021年7月9日在0:07

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