四川盆地长兴-飞仙关组的有利储集相带

为预测和优选有利的勘探区带，应用层序地层学的理论和方法，将四川盆地上二叠统长兴组-下三叠统飞仙关组划分为8个层序17个体系域，并建立了相关层序地层格架；通过对层序地层格架内沉积相展布的研究，发现该盆地长兴-飞仙关组发育台缘礁滩有利储集相带，并受开江-梁平海槽、鄂西-城口海槽及川西海槽的控制，沿海槽两侧呈条带状分布；通过台缘礁滩分布预测成果，结合多种地质信息进行综合分析，划分出3大类8小类有利勘探区带：Ⅰ.台缘礁滩区，包括鄂西-城口海槽西侧、开江-梁平海槽东侧、开江-梁平海槽西侧、川西海槽两侧；Ⅱ.台内礁滩区，包括川西区块、川中区块；Ⅲ.台内白云岩区，包括川南区块、川东区块。其中Ⅰ类是最为有利的勘探区带，是当前勘探的重点；Ⅱ类是Ⅰ类的有益补充，虽然取得了一定的突破，仍需要进一步加强勘探；Ⅲ类面积大，整体勘探和研究程度低，应加强综合地质研究，力争早日取得勘探突破。

Favorable reservoir facies tracts in the Changxing-Feixianguan formations of Sichuan Basin

In order to predict and optimize favorable exploration plays, we used the theory and methodology of sequence stratigraphy to divide the Changxing Feixianguan formations in the Sichuan Basin into 8 sequences and 17 system tracts and to establish a relevant sequence stratigraphic framework. A study on the distribution of depositional facies within the sequence stratigraphic framework revealed that favorable platform margin reef flat reservoir facies tract occurs in the Changxing Feixianguan formations. This facies tract is controlled by Kaijiang Liangping, Exi Chengkou and Chuanxi (West Sichuan Basin) troughs and is in banded distribution on both sides of the troughs. Based on the prediction results of the platform margin reef flat facies and in combination with various geologic data, we identified 3 types and 8 subtypes of favorable reservoir facies tracts. Type Ⅰ is platform margin reef flat facies which is distributed on the western side of Exi Chengkou trough, both eastern and western sides of Kaijiang Liangping trough, and both sides of Chuanxi trough. Type Ⅱ is inner platform reef flat facies which is distributed in Chuanxi and Chuanzhong (Central Sichuan Basin) areas. Type III is inner platform dolomite which is distributed in Chuannan (South Sichuan Basin) and Chuandong (East Sichuan Basin) areas. Among them, type Ⅰ facies tract is the most favorable for exploration and the focus of current exploration, while as a supplement to type I, the exploration of type Ⅱ facies tract should be further strengthened though certain breakthrough has been made now. In contrast, type III facies tract is large in area but low in exploration maturity as a whole, so comprehensive geologic study should be enhanced.