高邮凹陷阜一段致密砂岩孔隙演化差异分析

Differences analysis for porosity evolution of tight sandstone in the first member of Funing Formation in Gaoyou Sag

通过微观薄片图像、压汞实验与埋藏史等分析手段,对高邮凹陷阜一段致密砂岩开展了成岩作用与孔隙演化的定量分析,认为其成岩过程十分复杂,压实与胶结作用强烈,成岩阶段多进入中成岩A2期。而且由于后期的不规则抬降运动,导致其储层物性不仅存在与深度关系不匹配的现象,也存在各构造单元储层物性与深度关系自成独立演化的现象。研究表明南部断裂带阜一段储层的现今埋深远小于最大古埋深,具有先致密后成藏的特点,孔隙度和渗透率虽然低,但是有效孔隙的联通性较好,油藏通过压裂可以获得较好的产能。而内坡—深凹带地区的现今埋深大于古埋深,具有成藏后又进一步致密化的特点,这导致该区油藏含油饱和度较高,但是孔隙的联通性较差,开发较为困难。

The diagenesis and porosity evolution of tight sandstone in the first member of Funing Formation in Gaoyou Sag were quantitatively analyzed by microscopic thin section image, pressure mercury experiment and burial history analy- sis. The results of analysis indicated that the diagenetic process with strong the compaction and cementation was very com- plicated, and the diagenetic stages mostly entered into the middle diagenetic stage A2. Moreover, because of the irregular movement at the late stage, there is not only a mismatch of relationship between reservoir physical property and depth, but also a self - independent evolution of relationship between reservoir physical property and depth for each tectonic unit. The present buried depth of reservoir in southern fault zone is less than the maximum paleo buried depth. And the reservoir had characteristics of early densification and late accumulation. Although the porosity and permeability are low, the connectivity of effective porosity is better. As a result, good productivity of wells could be obtained by fracturing stimulation. The present buried depth of reservoir in inner slope and deep concave area is more than the paleo buried depth. And the reservoir had characteristics of early accumulation and late densification. There is higher oil saturation in this area, but the connectivity of effective porosity is poor. Therefore, it is difficult to develop the reservoir.