In the Es1 Formation in Qikou Sag, the interlaminated coccolith limestone and mudstone develops extensively, in some literature, it is classified as "oilshale" because of the oilbearing.
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”。
2
A shale formation with sandstone interbedded is also a potential oilbearing formation.
以泥岩为主,夹砂岩的地层也可能是油气层。
3
There are many factors to affect identification of oil and gas bearing layers in the sand-shale formation.