四川盆地东北部飞仙关组层序地层与储层分布

SEQUENCE STRATIGRAPHY AND RESERVOIR DISTRIBUTION OF FEIXIANGUAN FORMATION IN NORTHEASTERN SICHUAN

四川盆地东北部飞仙关组层序界面主要有水下间断不整合面及暴露侵蚀不整合面等两类界面,相当于PeterVail的类层序界面。通过对南江桥亭及PG2井等典型剖面解剖,将飞仙关组划分为两个沉积层序,厘清层序与储层的关系:储层主要位于三级层序高水位体系域中,其中,第一层序的高水位体系域发育浅滩鲕粒白云岩储层,其构成了川东北地区飞仙关组储层主体,第二层序高水位体系域发育浅滩相鲕粒灰岩储层。建立飞仙关组层序地层格架,对储层二维空间分布进行预测认为,浅滩鲕粒白云岩储层主要分布于PG2井-宣汉渡口立石河之间,浅滩鲕粒灰岩储层主要分布于南江桥亭及CP82井等地。浅滩鲕粒白云岩储层分布广,区域上分布于通江-开县局限台地及其西侧,浅滩鲕粒灰岩储层主要分布在通南巴地区及东部城口-万源一带。

Initial prediction of reservoir of Feixianguan Formation on the basis of the study of sequence stratigraphy of Feixianguan Formation in northeastern Sichuan. The sequence boundaries of Feixianguan Formation include undersea gap unconformity boundary and exposed and eroded unconformity boundary, which is similar to Type 2 sequence boundary of Peter Vail. Sequence of the Feixianguan Formation are classified into two by the study of Nanjiang Qiaoting section and core of PG 2. The relation between reservoir and sequence stratum is determined and the reservoir mainly occurs in the HST of a sequence. Main reservoir is exposed shoal evaporate flat oolite dolomite reservoir in the HST of the 1 sequence, and oolite limestone reservoir of shoals facies in HST of the 2 sequence. This paper makes prediction on 2 dimensionl distribution of reservior on the basis of establishment of sequence stratigraphy. It is considered that exposed shoal- evaporate flat oolite dolomite reservoir occurs between PG 2 well and Lishi river of Xuanhan Dukou, and oolite limestone reservoir of shoals facies occurs Nanjiang-Qiaoting areas. In conclusion, exposed shoal- evaporate flat oolite dolomite reservoir are widely distributed in platform evaporite of Tongjiang-Kaixian, and oolite limestone reservoir of shoals distribute mainly in Tongnanba areas and Chnegkou Wanyuan zone. So more attension should be paid to look for oil and gas in exposed shoal reservoir.