鄂尔多斯盆地延长组储层胶结物形成机理及地质意义

鄂尔多斯盆地上三叠统延长组储层普遍具有岩石成分复杂、成熟度低、磨圆度低和物性较差的特征．属典型的特低孔、低渗储层。强烈的胶结作用和压实作用为储层致密的主要控制因素。应用X射线衍射（XRD）、扫描电镜（SEM）和偏光显微镜等对胶结物的分布、组合类型及赋存状态进行了分析，在借鉴现代湖泊沉积学研究的基础上。探讨了沉积和地层流体化学组成与黏土、碳酸盐和硅质胶结物的关系。结果表明：沉积流体控制了陆源碎屑黏土矿物在湖盆中的分布，控制了陆源碎屑黏土矿物向自生黏土矿物的转化．控制了碳酸盐胶结物的形成与分布。地层流体化学组成为胶结物的形成提供了物质基础和特定的成岩环境。该研究成果为有利成岩相定性一半定量预测提供了依据。

Formation mechanism of reservoir cement of Yanchang Formation in Ordos Basin and its geological significance

The reservoir of Triassic Yanchang Formation in Ordos Basin generally is characterized by complex composition, low maturity and roundness of rocks and poor physical properties, and belongs to typical ultra-low porosity and low permeability reservoir. Strong cementation and compaction are the main controlling factors for reservoir densing. X-ray diffraction, scanning electron microscopy and polarizing microscope were applied to analyze the distribution, assemblage types and occurrence of cements. Based on the study of modem lake sedimentology, the relationship between deposition and formation fluid composition and clay, carbonate and siliceous cements was discussed. The results show that the sedimentary fluid controls the distribution of detrital clay minerals in the lake basin, controls the conversion from detrital clay minerals to authigenic clay minerals, and controls the formation and distribution carbonate cements. Formation fluid chemical composition provides material basis and specific diagenetie environment for the cementation. This study provides the basis for the qualitative-semiquantitative prediction of favorable diagenetic facies.