鄂尔多斯盆地北部上古生界层序地层学特征

鄂尔多斯盆地北部是中国石油长庆油田公司天然气增储上产的重点地区。以高分辨率层序地层学理论和技术方法为指导，在对该区地表露头、钻井岩心、测井、地震资料综合研究的基础上，通过基准面旋回结构、叠加样式的沉积动力学分析，将该区上古生界太原组-下石盒子组划分为8个长期、17个中期和若干个短期旋回层序，并详细讨论了各期旋回层序特征。结果认为：基准面旋回层序的类型与储集砂体的发育有着密切的关系，最有利储集砂体通常出现在中、长期旋回层序的界面两侧，并以普遍发育A型和C₁ 型短期旋回层序结构为显著特征；其中以具备A₁型结构的短期旋回层序为最有利于储集砂岩发育的位置，是该区上古生界天然气勘探的主要目标。

Sequence stratigraphic features of the Upper Paleozoic in north Ordos basin

The northern Ordos basin is one of the major areas for gas accumulation and also the important area for gas reserve growth of PetroChina Changqing Oilfield Company. Under the guidance of the theories and methodologies of high resolution sequence stratigraphy, the Upper Paleozoic Taiyuan Formation Lower Shihezi Formation were divided into 8 long term, 17 middle term and several short term cyclic sequences and the features of each cyclic sequence were discussed in detail through sedimentary dynamical analysis of base level cycle structure and stacking pattern with outcrop, drilling core, log and seismic data in the study area. It is believed that the type of base level cyclic sequence is closely related with the development of reservoir sandbodies, the most favorable of which commonly occur on both sides of the middle and long term cyclic sequence boundaries and are characterized by the prevalence of A and C1 type of short term cyclic sequence structures. The short term cyclic sequence with A1 type of structure is most favorable for the development of reservoir sandbodies, thus are the major targets for gas exploration in the Paleozoic in the study area.