In the Es1 Formation in Qikou Sag, the interlaminated coccolith limestone and mudstone develops extensively, in some literature, it is classified as "oil shale" because of the oil bearing.

歧口凹陷古近系沙河街组一段广泛发育颗石灰岩与泥岩的纹层状互层，因其含油而被误认为“油页岩”。

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A shale formation with sandstone interbedded is also a potential oil bearing formation.

以泥岩为主，夹砂岩的地层也可能是油气层。

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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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What if it is right there trapped in oil and natural gas-bearing shale, enough to possibly supply our U.S. needs for centuries?

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He says the Bakken has a layer of nearly impermeable shale that sits above the oil-bearing reservoirs.

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