川东北铁山-黄泥塘地区飞仙关组鲕滩沉积特征及分布规律

Sedimentary charactersitics and distribution regularity of oolitic beach reservoirs in Feixianguan formation in Tieshan—Huang Nitang area of Northeast Sichuan Basin

综合运用钻井、测井、岩心和区域构造资料,对铁山-黄泥塘地区飞仙关组鲕滩沉积分布特征进行了详细研究,认为晚二叠世逐渐发育形成的北西向开江-梁平海槽对研究区飞仙关期鲕滩的分布起着初步的控制作用,同时北东向的基底断裂切割台地形成的相对隆升或凹陷,对区内飞仙关期鲕滩的分布起着进一步的修饰作用。结合全球海平面变化情况,认为扬子区晚二叠世长兴末期发育一次较大的海退,研究区飞仙关期鲕滩主要发育在海退中后期。飞仙关早期由于研究区呈台槽分异的沉积格局,区内主要发育台缘鲕滩;到飞三期海槽已基本填平,只在台地内部海底微地貌高地上发育台内鲕滩;飞四期由于海槽的完全填平,颗粒滩不再发育,研究区逐步演化为区域性潮坪相。

By comprehensively using drilling, logging, coring and regional structure material analysis, the sedimentary characteristics of oolitic beach reservoirs in Feixianguan formation in Tieshan-Huang Nitang area have been carefully studied. The results indicate Kaijiang-Liangping trough with northwest direction gradually developed in the late Permian performs the control function on the distribution of the oolitic beach. At the same time, the relative uplift or depression developed by basement fracture with northeast direction through cutting also has an effect on the distribution of the oolitic beach. In combination with global sea level changes, it is believed that during late Permian there was a larger regressive at the end of Changxing period, and the oolitic beach was mainly developed in the mid-late period of regressive. At the early stage of Feixianguan period, because of platform groove differentiation sedimentary pattern, Platform margin oolite beach was mainly developed. Up to the Feisan period, as the trough was basically filled, the oolite beach inside platform was only developed in submarine microrelief highlands. As the trough was completely filled up, the particle beach was no longer developed and the research area gradually evolved into regional tidal-flat facies.