风化淋滤对碎屑岩储层的改造作用——以山东博山地区大奎山下石盒子组为例  

Effect of Weathering Leaching on Clastic Reservoir:A Case Study of Shihezi Formation in Dakuishan,Boshan Area,Shandong Province

作　　者：丁建凯 朱占平[1] 胡逸飞 DING Jiankai;ZHU Zhanping;HU Yifei(College of Earth Sciences,Jilin University,Changchun,Jilin 130000)

机构地区：[1]吉林大学地球科学学院,吉林长春130000

出　　处：《中国煤炭地质》2023年第5期6-13,19,共9页Coal Geology of China

摘　　要：大奎山上古生界下石盒子组风化壳剖面位于山东省淄博市博山区,通过对剖面观察实测及铸体薄片观察、全岩矿物组成分析、黏土矿物分析、主量元素测定以及物性测定等手段,研究风化淋滤对碎屑岩储层的改造作用。研究表明,经过风化淋滤改造,风化壳上部长石等抗风化能力弱的矿物已淋滤殆尽,转化为高岭石等黏土矿物,K、Ca、Na等易迁移元素流失,Fe、Ti等难迁移组分沉淀析出。依据风化程度及元素分布特征,识别出大奎山下石盒子组剖面遭受中等—强风化。通过纵向分带的储集性能研究,表明风化淋滤作用对砂岩物性具有明显的改善作用,孔隙度平均9.49%,渗透率平均1.59mD,相比未风化同地层储集物性有很大改善,强风化带砂岩层储集物性好,中等风化带砂岩层次之。同时,风化黏土对砂岩层产生强烈的胶结作用,导致强风化带黏土层和砂岩层交界处储集物性异常,除此之外,越靠近风化壳顶部,风化淋滤作用进行得越彻底,储集性能越好。风化壳强风化带砂岩层为优良储层发育位置,强风化带黏土层可作为局部盖层。The weathering crust profile of the Lower Shihezi Formation of the Upper Paleozoic in Dakuishan is located in Boshan District,Zibo City,Shandong Province.The transformation effect of weathering leaching on clastic rock reservoir was studied by means of profile observation,cast thin section observation,analysis of mineral composition of whole rock,clay mineral analysis,principal element measurement and physical property measurement.The results show that after weathering leaching,minerals with weak weathering resistance such as feldspar in the upper part of the weathering crust have been leaching out and converted into clay minerals such as kaolinite,and the movable elements such as K,Ca,Na are lost,while Fe,Ti are precipitated out.According to the weathering degree and the distribution characteristics of elements,it is identified that the profile of Shihezi Formation under Dakuishan is subjected to moderate to strong weathering.Through the study of reservoir properties of longitudinal zonation,it is shown that weathering leaching has a significant effect on the physical properties of sandstone.The average porosity is 9.49%,and the average permeability is 1.59mD.Compared with unweathered reservoirs,the physical properties of sandstone reservoirs in the strong weathering zone are better,and the sandstone layers in the medium weathering zone are better.At the same time,the weathering clay exerts strong cementation on the sandstone layer,resulting in abnormal reservoir properties at the junction of the clay layer and the sandstone layer in the strongly weathered zone.In addition,the closer the weathering crust is to the top,the more thorough the weathering leaching process is,and the better the reservoir performance is.The sandstone layer in the strong weathering zone of weathering crust is the excellent reservoir development location,and the clay layer in the strong weathering zone can be used as local cap layer.

关 键 词：下石盒子组 储层物性 博山 

分 类 号：TE122.2[石油与天然气工程—油气勘探]