准噶尔盆地柴窝堡凹陷二叠系储层成岩作用

Diagenesis characteristics of Permian reservoir in Chaiwopu Depression,Junggar Basin

根据岩心、岩石薄片、X射线衍射、扫描电镜和电子探针等资料,对准噶尔盆地柴窝堡凹陷二叠系红雁池组储层成岩作用特征及其对储集物性的影响进行了研究。结果表明,红雁池组储层岩石具有成分成熟度和结构成熟度均较低的特点,岩石类型主要为细砾岩和岩屑砂岩,岩屑类型以凝灰岩岩屑为主;储集空间以粒间溶孔为主,属超低孔、超低渗储层。储层成岩阶段主要为中成岩阶段A期,其中压实作用导致原生孔隙大量丧失,是研究区最主要的破坏性成岩作用;黏土矿物胶结作用使储层孔渗性降低;碳酸盐矿物和沸石矿物胶结作用均具有双重影响,二者在支撑碎屑颗粒、减弱压实作用强度的同时,为后期溶蚀作用的发育提供了物质基础;溶蚀作用使次生孔隙发育并使孔缝连通,是研究区重要的建设性成岩作用。

Based on the data from core drilling,rock thin sections,X-ray diffraction,scanning electron microscope and electron probe,the diagenesis characteristics and its impact on reservoir quality of Permian Hongyanchi Formation were studied.The reservoir rock types of the Permian Hongyanchi Formation mainly include conglomerate and lithic sandstone,with low compositional maturity and textural maturity.It belongs to ultra-low porosity and ultra-low permeability reservoir,with dissolved intergranular pores as the chief accumulation space.The reservoirs of Hongyanchi Formation now are in the A stage of mesodiagenesis,and the main diagenesis include compaction,cementation,dissolution and replacement.The compaction caused the losing of primary pores,and it is the predominant reason for the destruction of reservoir quality in the study area.The cementation of clay minerals made the reservoir properties poor.The cementation of carbonate and zeolite has two different influences on reservoir quality.The carbonate and zeolite cements can not only preserve some primary intergrannular porosity by supporting clastic particles and weakening the degree of mechanical compaction,but also provide the abundant dissolved matter,making a large number of secondary pores produced.Dissolution is the most important factor for improving the reservoir quality in the study area.On the one hand,dissolution can produce a large number of secondary pores;on the other hand,dissolution is positive to petroleum migration by connecting pores and fractures.