Abstract: Interlayers with different scales not only affect the seepage flow vertical and horizontally, but restrict the development of oilfield injection-production horizon and perforation layer segment as well. Take the example of major sandbodies with the biggest proven reserves in some specific oilfield; the fine study on interlayers characteristics has been conducted from the start of reservoir and in combination with logging, testing and mud logging data as well. The research results indicate the non reservoir among the gas cap is a poor limestone reservoir with muddy, not a pure of non-permeable mudstone, which provides a powerful technical support for FDP and be confirmed by the subsequent development, being of guidance and reference for the interlayers of the similar kinds.