莺歌海盆地异常高孔带分布与成因分析

Distribution and Causes Analysis of the Anomalously High Porosity Zones of the Yinggerhai Basin

为了在高温、高压背景下寻找发育异常高孔隙度的优质储层，本文应用大量岩心实测孔隙度、铸体薄片和扫描电镜等资料，研究了莺歌海盆地碎屑岩储层异常高孔带的纵向分布特征及其成因。结果表明，莺歌海盆地在300～1150m、1300～2400m、〉3000m发育三个异常高孔带。第1异常高孔带主要分布于莺歌海盆地乐东区，第1I异常高孔带主要分布于东方区、乐东区和莺东斜坡区，第1II异常高孔带分布于临高区和东南区。异常高孔带的成因主要有大气水淋滤、有机酸溶蚀、热流体活动、天然气侵位、超压对机械压实作用的抑制。邻源超压比他源超压对机械压实具有更明显的抑制作用。异常高孔带主要发育于水动力较强的临滨和浅海相砂体中，这些砂体具有刚性颗粒含量高、分选中一好、胶结物含量低的特征。

In order to discover the high quality reservoirs with anomalously high porosity under high temperature and high pressure, vertical distributions and causes of anomalously high porosity zones in elastic reservoirs were studied using lots of measured porosity data, blue epoxy resin-impregnated thin sections and SEM in the Yinggerhai Basin. The results show that three anomalously high porosity zones exist at 300m-1150 m, 1300-2400 m, below 3000 m layers in the basin. Horizontally, the first anomalously high porosity zone distributes mainly in the Ledong Dis- trict of the basin, and the second distributes in the Dongfang District, the Ledong District and the Yingdong Slope District, while the third locates in the Lingao District and the Dongnan District. The anomalously high porosity zones were formed by meteoric water leaching, gas replacement, and dissolution caused by organic acids and geo- thermal fluids, and the retardation toward mechanical compactions caused by overpressures. The adjacent source o- verpressure retardates mechanical compaction more intensively than the allogenic source overpressure does. The a- nomalously high porosity zones mainly distribute in shore and neritic facies, in which water dynamic conditions are strong and the content of rigid particles are high.