济阳坳陷古近系泥页岩成因相划分

Genetic facies classification of Paleogene mudstone in Jiyang depression

系统岩心观察和高密度薄片鉴定等分析测试资料研究结果显示,济阳坳陷沙三下-沙四上泥页岩成分组成及构造类型主要受沉积作用控制,岩石结构特征主要受成岩作用控制。根据泥页岩中方解石成因及重结晶程度,结合岩石成分及构造特征,将济阳坳陷沙三下-沙四上泥页岩划分为沉积主控型、沉积-成岩双控型及成岩主控型三大成因相。沉积主控型分布最为广泛,岩相类型多样,构造特征反映成因环境;沉积-成岩双控型主要见于纹层状岩相,由泥质纹层与显晶粒状方解石纹层互层构成;成岩主控型以柱状、柱纤状方解石垂直层面呈脉状、透镜状产出为特征。成岩主控型和沉积-成岩双控型泥页岩与页岩油气关系密切,是重要的有利成因相类型。

On the basis of core observation and high density slice identification, the authors consider that Es3x-Es4s mudstone in Jiyang depression is mainly controlled by sedimentation and diagenesis. The composition and structure types are mainly controlled by sedimentation, whereas crystal texture characteristics are mainly controlled by diagenesis. According to the genesis and degree of recrystallization of calcite, combined with the mineral composition and structure characteristics, the Paleogene mudstone in Jiyang depression can be divided into three types, i.e., sedimentation-controlled type, sedimentation and diagenesis-controlled type and diagenesis-controlled type. The sedimentation-controlled type is the most widely distributed type which includes various types of lithofaces and whose structural characteristics reflect the formation environment. Sedimentation and diagenesis-controlled type mainly appears as laminated rock facies consisting of interlayered laminae of the argillaceous and granular crystallized calcite. Diagenesis-controlled type is characterized by column or fiber-column calcite crystals in the veined or lenticular forms perpendicular to the bedding plane. The diagenesis-controlled type and sedimentation and diagenesis-controlled type are closely related to Oil and gas in shale, and they are the most favorable genetic lithofacies.