盐湖环境成岩作用特征及其对高孔隙带形成的影响

Characteristics of diagenesis saline lake environment and its effect on high-porosity zones

渤海湾盆地东濮凹陷黄河以北地区古近系沙河街组沉积于典型的咸水—盐湖环境,发育巨厚的盐岩层,碳酸盐胶结强烈,硫酸盐矿物呈层状或块状分布,黏土矿物中以伊利石含量最高,边溶蚀边交代作用显著。其成岩作用具有明显的盐湖盆地特点,使沙河街组纵向发育次生高孔隙带,约2500m深度的第一次生孔隙发育带一般孔隙度大于20％,2850～3700m的第二次生孔隙发育带孔隙度约为14％。

In a Lower Tertiary System, the sedimentary environment of Dongpu Sag was a typical saline lake . It characterized by high-salinity and strong alkality. The diagenesis is salient characteristic of the saline lake basin. There is a lot of gypsum and halite, illite has an advantage in the clay minerals, and dissolution and metasomatism are very common and strong. The porosity within the original zone around the depth 2500m is over 20% and the secondary porosity developed zone around depth ranging 2850-3700m are about 14%.