风化粘土层-半风化岩石型不整合的矿物学、地球化学特征

不整合是构造运动和海(湖)平面升降的产物,其风化粘土层可作为油藏的良好封盖层,半风化岩石孔缝系统可作为油气运移通道,也可为油气聚集提供良好储层.深入分析不整合结构在矿物含量变化、元素及其氧化物含量变化方面的微观特征是划分不整合结构的基础,对不整合油气藏的勘探实践具有重要意义.不整合结构可划分为风化粘土层一半风化岩石型、半风化岩石型和沉积间断型.通过济阳坳陷义和庄凸起前第三系风化粘土层一半风化岩石型不整合结构矿物与元素变化的实测数据,结合典型地区风化壳的矿物、元素分析结果,分析了风化粘土层一半风化岩石型不整合结构的矿物学、常量元素地球化学特征:其矿物学特征主要表现为长石、云母等原生矿物的蚀变和高岭石、伊利石及蒙脱石等次生粘土矿物的明显增多,粘土矿物在风化粘土层中部或风化粘土层下部一半风化岩石上部较为富集;其常量元素地球化学特征表现为Ca、Na元素含量迅速减少,在风化粘土层下部与半风化岩石上部通常具有Fe、Al元素的富集带,K、Mg元素的变化由于交代作用等因素而变得复杂.

Mineralogical and Geochemical Characteristics of Unconformity Structure with Weathered Clay and Sapropelic Rock

The unconformity is formed due to the tectonic movement and the eustatic sea level change.The unconformity structure is very important for the pool forming.If the weathered clay is thick enough,it can become good capping layer.The pores,fissures and their connecting systems in the sapropelic rock provide good migrating channel and accumulating place for oil.Studying the mineralogical and geochemical characteristics of unconformity structure is the basic of the structure division which is important for the e...