西湖凹陷Y构造花港组黏土矿物特征及对储层物性的影响

Clay Mineral Characteristics of Huagang Formation and Impact on the Physical Property of Sandstone Reservoir in Structure Y of Xihu Sag

通过X射线衍射、扫描电镜等方法对Y构造花港组致密储层中黏土矿物含量、形态特征进行研究,分析其在不同成岩作用阶段的演化过程及对储层物性的影响,结果显示成岩演化过程中高岭石和蒙脱石含量越高,钾长石溶蚀消耗越强烈,储层次生孔隙越发育;反之钾长石消耗少,孔隙相对不发育。随着成岩作用加强,绿泥石和伊利石含量增加,储层孔隙度变化不明显,但渗透率明显下降。分析认为绒球状绿泥石和丝发状伊利石含量不断增加,堵塞储层中细小喉道,致使渗透率明显变差。

According to the data of XRD and SEM, the authors studied the content, morphological characteristics of clay minerals in the tight sandstone reservoir, analyzed the evolution process in different diagenetic stages and their influence onthe physical property of sandstone reservoirs in Huagang Formation. The study shows that kaolinite and montmorillonite had important effect on potassium feldspar resolution in the diagenesis. Enough kaolinite and montmorillonite promoted the resolution of feldspar and the development of secondary pore. Otherwise, less feldspar resolution means less secondary pore. With the intensification of diagenetic degree, the content of chlorite and illite increased. Correspondingly, the porosity of reservoir didn＇t alter obviously, but the permeability decreased dramatically. It is thought that with the increase of chlorite clusters and illite fibers they blocked the fine throat and deteriorated the permeability.