摘要
鄂尔多斯盆地泥页岩储层纯页岩段黏土矿物含量高,储集空间体积小。因此,黏土矿物转化释放的二氧化硅缺乏足够的空间,不能生长成自生石英,只能以非晶态存在于黏土矿物之间;而其粉砂质泥岩夹层中常见微米级孔洞。孔洞由长石溶蚀和黏土矿物转化形成,内部则发育晶形完好的自生石英、绿泥石及含铁方解石。此外,粉砂质泥岩的碎屑颗粒间常发育结块状非晶态二氧化硅,碎屑石英颗粒周围则以次生加大边的形式发育粒状和席状(或片状)非晶态二氧化硅。二氧化硅主要来源于黏土矿物转化与石英碎屑颗粒溶蚀。
Mud shale reservoirs of the Yanchang Formation in the Ordos basin has high content of clay in the pure shale section,thus space for accumulation and reservoirs is very limited.SiO_2 released from clay mineral transformation can not grow into authigenic quartz,but occurs only as amorphous quartz growing among clay minerals.Whereas Interlayers of silty mudstone contain micrometer scale pores,which are formed by feldspar dissolution and clay minerals.Authigenic quartz with perfect crystal morphology,chlorite and ferrocalcite are developed inside micron-sized pores of silty mudstone interlayers.Amorphous silica accumulates and deposits among detrital minerals in silty mudstone interlayers and grows around quartz particles in the form of granular and sheet silica by secondary enlargement.Silica is mainly derived from transformation of clay minerals and dissolution of quartz grains.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2016年第5期1016-1029,共14页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号41272156)
中国石油天然气集团公司天然气成藏与开发重点实验室联合资助成果
