黄骅坳陷北大港构造带古近系沙河街组高分辨率层序地层格架及其对储层非均质性的控制

HIGH-RESOLUTION SEQUENCE-STRATIGRAPHIC FRAMEWORK AND ITS CONTROL ON THE RESERVOIR HETEROGENEITIES OF BEIDAGANG TECTONIC BELT IN HUANGHUA SAG

陆相湖盆层序的发育是在湖盆蓄水量周期性变化的条件下实现的。层序发育过程实际上是基准面旋回变化过程中湖泊冲刷沉积作用彼此消长的过程。北大港构造带古近系沙河街组可划分为2个长期基准面旋回、8个中期基准面旋回和43个短期基准面旋回。在等时地层格架内,基于基准面变化过程中的沉积响应及其伴生的可容空间变化的分析,探讨了基准面旋回变化与储层展布及储层非均质性之间的相关关系:基准面旋回的升降变化对储层的非均质性、空间展布以及有利储层的分布等均具有明显的控制作用;短期基准面旋回控制储层砂体内部的非均质模式,中长期基准面旋回控制了储层砂体的层间非均质性特征;在中长期基准面低位处,尤其是在基准面旋回的转换点处,储层发育良好,砂体厚度、展布面积均较大,物性相对较好;而在中长起基准面较高位处,则出现相反的储层特征。

Evolution of the sequence of the continental basins reflects the periodic changes of lake water regime. Thus the reacting sequence of the lacustrine deposits expresses the genetic history of the oil an gas pool. In the study area, 2 long-term cycles, 8 medium-term cycles and 43 short-term cycles were identiffed and correlated. According to the process-response analysis in the base-level cycles, reservoir heterogeneities and its relation to base-level are discussed. Our research shows that reservoir distribution and i heterogeneities were obviously controlled by the base-level. The base-level controlled the property of sandbody. The short-term cycle controlled the characteristic of heterogeneities in sandbody, and the mediun and long-term cycle controlled the inter-layer heterogeneities. On the lower location of the medium-and long-term base-level, the sandbody is well developed, with a wide area and great thickness, while on tt high location of the base-level, there is an opposite reservoir character.