鄂尔多斯志丹地区延长组高分辨率层序地层模式探讨

The Discussion of the High-resolution Sequence Stratigraphy Models of Yanchang Formation in Zhidan Area of Ordos Basin

根据岩心、野外露头、测井、录井岩性等资料,在高分辨率层序地层学理论体系的指导下,按照适合陆相盆地层序特征的研究思路,对鄂尔多斯盆地陕北斜坡带志丹地区延长组地层特征进行了研究。对志丹地区延长组不同相带、不同旋回中岩性组合特征进行分析,总结出了该地区延长组层序界面的类型和识别特征;并对延长组基准面旋回特征进行讨论和长期基准面旋回的划分。最后在此基础上提出志丹地区延长组长10—长4+5时期的高分辨率层序地层模式。认为延长组从下至上可以划分为四个长期基准面旋回,其中LSC1对应长10和长9油组;LSC2对应长8和长7油组;LSC3对应长6和长4+5油组;LSC4对应长3、长2和长1油组。LSC3生储盖组合配置良好,且处于油气运移的有利指向上,是志丹地区主要的产油层段。

According to the information of drilling core,field outcrop, logging curves,lithologic combina- tion etc, under the guidance of the high resolution sequence stratigraphy theory system, on the basis of re- search ideas which suitable for continental basin sequence characteristics, the sequence stratigraphy ok Yanchang Formation in Zhidan area of the Shanbei slope in Ordos Basin is studied. The lithologic charac- ters of Yanchang Formation in Zhidan area with different facies and circles is analysed, summarized the type of high resolution sequence stratigraphy interface and the recognition features in Zhidan area, divided the long-term stratigraphic base-level circles of Yanchang Formation and analyzed the characteristics of each base level cycle. Finally, on that basis, the high resolution sequence stratigraphic model of Yanehang Formation in Zhidan area during the time between Chang10 and Chang4＋5 is put forward. Yanchang For- mation can be divided into four long-term base-level cycles from the bottom to the top is concluded. And LSC1 is correspond with Chang10 oil layer and Chang9 oil layer, LSC2 is correspond with Chang8 oil layer and Chang7 oil layer, LSC3 is correspond with Chang6 oil layer and Chang4＋5 oil layer, LSC4 is corre- spond with Chang3 oil layer ,Chang2 oil layer and Chang1 oil layer. With a good source-reservoir-caprock association , located in a favorable direction of oil and gas accumulation, LSC3 is the main oil producing in- terval of Zhidan area.