摘要
陕甘宁盆地奥陶系碳酸盐古风化壳天然气储集层中存在丰富的高岭石族矿物，经扫描电镜观察、单矿物样的Ｘ射线衍射、红外吸收光谱及差热分析，确认为地开石，而不是高岭石。由于地开石的存在反映酸性的成岩介质，这不利于作为孔隙封堵物的高铁、锰方解石和白云石的沉淀，而有利于碳酸盐矿物的溶解，对埋藏成岩过程中储层孔隙的保存与发育极为有利；同时由于地开石的分子体积小于高岭石，高岭石向地开石的转化会有多余的孔隙空间出现．并形成更多的晶间孔隙，因而地开石通常是好储层的指示矿物。此外．据该地开石形成温度判断，奥陶系碳酸盐储层所经历的最大古地温为１４０～１６０℃。
There are a number of kaolinite subgroup clay minerals in the Ordovician carbonate sediments of Shaanganning Basin. They were studied by scannins electron microscopy, X-ray powderdiffraction,infrared absorption spectroscopy and differential thermogram analysis and comfirmed thatthiS kind of mineral is dickite and not kaolinite. Since depth-dependent transformation of kaolinite todickite needs acidic diagenetic agent,the present dickite indicates the activity of relatively acidic porefluid during diagenesis. Under this condition,calcite and dolomite rich in iron and manganese sealingoff most of the porosity could not precipitate. So,dickite is an indicator of good reservoirs. In addition,the maximum palaeotemperature of Ordovician carbonate reservoir underwent was approximately140-160℃ by means of the geothermometer of dickite.
出处
《成都理工学院学报》
CSCD
1995年第3期43-51,共9页
Journal of Chengdu University of Technology
关键词
储集层
地开石
碳酸盐
风化壳
油气藏
Shaanganning Basin
Ordovician
carbonate reservoir
dickite
palaeotemperature
