There are many factors to affect identification of oil and gas bearing layers in the sand-shale formation.

在砂泥岩地层中，影响油、气层识别的因素较多，尤其在复杂地质条件下准确识别油气层难度更大。

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According to the nature, Guangxi limestone is separated into three types: pure limestone, siliceous limestone, mixed sand shale or limestone of igneous rock.

广西的石灰岩按性质可分为纯质石灰岩、夹硅质石灰岩、夹砂页岩或火成岩的石灰岩三种类型。

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The aeolian silty sand in shale can provide good guide to study of paleoclimate about lacustrine shale and varve, and to reconstruct sedimentary environment of paleolake accurately.

页岩中风成粉砂沉积的发现，可以进一步为研究有关湖相页岩和第四纪纹泥的古气候变化、正确恢复古湖泊沉积环境提供良好的指标。

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They drill down to the shale, then go sideways and inject high-pressure water, sand or other material into the rock.

VOA: special.2009.10.23

More than 10 drillers have already received Department of Environmental Protection permission to use mine discharges for fracking, a technique in which millions of gallons of water, along with chemical additives and sand, are pumped down a well to break apart gas-bearing shale deposits.

WSJ: Pa. pushes drillers to frack with coal mine water

This part of Texas is in the core of the Eagle Ford s hale, currently the most profitable oil and gas field in the U.S. The people around here understand that the fracking of this shale, the injection of billions of gallons of sand-and-chemical-laden water, takes place 2 miles beneath the ground.

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Hydraulic fracturing pumps many thousands of gallons of mainly water and sand, with a few chemicals, at high pressure into tight gas-bearing shale deposits (hardened muds), creating cracks that allow gas to flow back up the well to the surface ( Shale Shock).

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