The organic matter abundance of sedimentary rock is low, and there is basically no effective source rock.

沉积岩的有机质丰度低，基本无有效生油岩发育。

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Exploration degree of Tarim Basin, however, is not high, so effective source rock distribution cannot be precisely defined only by geochemical index of the well sites.

而塔里木盆地勘探程度不高，仅凭井点的地化指标，是不能准确圈定有效烃源岩分布的。

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Second, source rock evaluation instead of effective source rocks evaluation, which results in overvalued thickness and quality of effective source rock and abundance of organic matter.

第二是以源岩评价代替对有效烃源岩的评价，致使有效烃源岩厚度、有机质丰度以及有效烃源岩品质评价过高。

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