松辽盆地齐家—古龙凹陷青山口组泥页岩层段储层特征

Reservoir characteristics of mudstone(shale)interval in the Qingshankou Formation,Qijia-Gulong Sag,Songliao Basin,northeast China

松辽盆地齐家—古龙凹陷青山口组富有机质泥页岩分布广泛,具有巨大的非常规油气勘探潜力。基于岩心观察、薄片、全岩X-射线衍射、氩离子抛光—环境扫描电镜、岩石热解以及有机碳分析资料,对青山口组泥页岩层段的储层特征进行了研究。结果表明：研究区的主要岩石类型为粉砂岩和低有机质页状粉砂岩,泥页岩中黏土矿物含量为6.1%~39.3%,总有机碳含量为0.74%~4.23%,有机质成熟度（RO）为0.62%~1.19%,属于低成熟—成熟演化阶段。泥页岩储层的主要储集空间为粒间孔、晶间孔、有机质孔、溶蚀孔以及微裂缝。青山口组泥页岩层段异常超压作用有助于抑制压实和胶结作用,促进溶蚀和天然裂缝形成,有利于形成泥页岩（致密）油勘探＂甜点区＂。

Organic-rich shale was widely distributed in the Qingshankou Formation,Qijia-Gulong Sag,Songliao Basin,which shows enormous potential in unconventional oil/gas exploration.Based on core observation,thin section,whole-rock X-ray diffraction,argon ion polishing-SEM analysis,rock pyrolysis analysis,and organic carbon analysis,reservoir characteristics in shale section of the Qingshankou Formation have been studied.According to the study results,the lithology in the study area was dominated by siltstone and shaley siltstone with low organic matter.The clay mineral content of the shale was 6.1%-39.3%,total organic matter content was 0.74%-4.23%,and organic matter maturity（RO）was 0.62%-1.19%,which indicate the shale were at low-mature to mature evolution stage.Major reservoir spaces in the shale section include intergranular pores,intracrystalline pores,organic pores,dissolved pores,and micro-fractures.The abnormal overpressure in the shale section of the Qingshankou Formation was contributed to restrain the compaction and cementation,and promote development of dissolution and natural fractures,which were favorable to form ＂sweet spot＂in shale（tight）oil exploration.