Abstract

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Title:: Genetic Classification of Sandy Braided-river Mudstone Based on Logging Response Characteristics—Taking L Oilfield in Bohai as an Example

Author(s):: XIE Chao; FAN Ting-en; FAN Hong-jun; XIAO Da-kun; CNOOC Research Institute, Beijing 100028, China

Keywords:: mudstone; braidedriver deposit; Guantao Formation; flooding mud; overflow facies mud; channel mud; logging response; scale forecast

Abstract:: Guantao Formation reservoirs in Liaodong Gulf, which are important oil and gas reservoirs in Bohai, are typical braided-river deposits. According to the analysis results of logging response characteristics, the classification scheme of mudstone was set up, and the sedimentary geneses of all kinds of mudstone were discussed; the plane scales of all kinds of mudstone were predicted based on the well-to-well correlation, combined with the analysis results of analogy. The results show that the braided-river mudstone of L oilfield in Bohai includes flooding mud, overflow facies mud and channel mud; the thickness of flooding mud is mostly more than 6 m, and it has stable distribution with predicted scale of more than 1 500 m, which belongs to interlayer with great planar continuity; the single layer thickness of overflow facies mud is usually more than 2 m, and this mud is continuous in local areas with predicted scale of more than 300 m, which affects reserve utilization; the thickness of channel mud is usually less than 2 m with bad continuity, and it has a limited planar distribution of less than 200 m, which has an influence on the pattern of horizontal well inclined to formation. The above results easily avoid reserve risk and have an important guiding significance to the choice and deployment of development well-type.