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西湖凹陷平湖组低渗储层成岩环境及孔隙演化

作    者:肖晓光, 侯国伟, 张 武, 姜 雪, 苗 清, 谢晶晶
单    位:中海石油(中国)有限公司上海分公司研究院
基金项目:本文受“十三五”国家科技重大专项课题 “东海深层大型气田勘探评价技术”资助
摘    要:
通过薄片鉴定、扫描电镜观察、包裹体分析、黏土矿物分析、镜质组反射率测试、电子探针和碳氧同位素分析,结合构造演化史和有机质热演化史研究成果,对西湖凹陷古近系平湖组碎屑岩储层的成岩环境和演化模式展开分析,恢复了储层孔隙演化过程并对孔隙度进行定量计算。结果表明:平湖组碎屑岩储层长期处于酸性成岩环境,同时存在酸碱过渡及碱性成岩环境,其中酸性成岩环境以碳酸盐矿物溶解、长石溶解蚀变为高岭石并伴生石英次生加大等为标志,碱性成岩环境以石英质颗粒及其次生加大边溶解、长石次生加大和含铁碳酸盐矿物沉淀为标志。研究区储层成岩环境大致经历了弱酸性—酸性—酸碱过渡—碱性的演化过程。建立了平湖组储层的孔隙演化模式,为研究区优质储层的预测提供了依据。
关键词:成岩环境; 成岩作用; 孔隙演化; 碎屑岩储层; 平湖组; 西湖凹陷

Diagenetic environment and pore evolution of the low permeability reservoir of Pinghu Formation in Xihu Sag

Author's Name: XIAO Xiaoguang, HOU Guowei, ZHANG Wu, JIANG Xue, MIAO Qing, XIE Jingjing
Institution: 
Abstract:
Through thin section identification, scanning electron microscope observation, inclusion analysis, clay mineral analysis, vitrinite reflectance test, electron probe and carbon and oxygen isotope analysis, combined with the research results of structural evolution history and thermal evolution history of organic matter, the diagenetic environment and evolution model of the clastic reservoir of the Paleogene Pinghu Formation in Xihu Sag are analyzed, and the pore evolution process is restored and the porosity is calculated quantitatively. The clastic reservoir of Pinghu Formation has been in acidic diagenetic environment for a long time, and sometime in acid- alkalinity transitional environment or alkaline environment. The acidic diagenetic environment is marked by dissolution of carbonate minerals, dissolution and alteration of feldspar into kaolinite and associated with secondary enlargement of quartz. The alkaline diagenetic environment is characterized by the dissolution of grains and their secondary enlarged edge of quartz, secondary enlargement of feldspar and precipitation of iron-bearing carbonate minerals. The diagenetic environment of the reservoir in the study area has roughly experienced the evolution process of weak acid—acid—acid-alkalinity transition—alkaline. The pore evolution model of Pinghu Formation is established, which provides a basis for the prediction of high-quality reservoirs in this area.
Keywords: diagenetic environment; diagenesis; pore evolution; clastic reservoir; Pinghu Formation; Xihu Sag
投稿时间:2021-03-31  
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