四川盆地西部晚二叠世吴家坪组沉积体系  

Sedimentary system of the Late Permian Wujiaping Formation in the western Sichuan Basin

作　　者：何江[1,2] 郑荣才[1] 胡欣[3] 张本健[3] 尹宏[3] 马华灵[3] 王勇[4] 冯春强[2] 

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]西南石油大学地球科学与技术学院,四川成都610500 [3]中国石油西南油气田分公司川西北气矿,四川江油621700 [4]中国石油西南油气田分公司川中气矿,四川遂宁629000

出　　处：《石油与天然气地质》2015年第1期87-95,共9页Oil & Gas Geology

基　　金：国家科技重大专项(2011ZX05004-005)

摘　　要：通过详细的野外剖面观察、地层横向追踪与对比、典型沉积剖面实测、系统取样和室内实验分析等方法,首次对四川盆地西部晚二叠世吴家坪组沉积体系进行精细研究,发现早二叠世末发生的东吴运动属拉张背景下的块断隆升,导致西南康滇古陆受古特提斯洋壳的推挤形成物源区,西北广元—旺苍一带伴生拉张沉降形成海槽地堑区,区内地势由南西向北东方向低角度倾斜,间接控制了吴家坪组沉积及岩相展布,显示宽缓渐变的沉积相带特征。研究表明,晚二叠世吴家坪组为早期风化剥蚀界面基础上一次较高海平面北西-南西向海侵的产物,南西至北西方向依次发育剥蚀区及冲积平原-滨岸平原-滨岸沼泽-碳酸盐岩缓坡沉积体系。其中,浅缓坡生屑滩发育区是最为有利的储集相带,其厚度大、分布面积广,且位于广元-旺苍生烃中心附近,具备就近俘获油气的能力。多轮数字地震详查也发现众多潜伏构造,为盆内碳酸盐岩气藏的扩大勘探展示了全新的后备领域。By means of detailed outcrop observation,lateral formation tracking and correlation,realistic writing of typical sedimentary section,systematic sampling and laboratory experimental analysis,detailed study was performed for the first time on sedimentary system of the Late Permian Wujiaping Formation in the western Sichuan Basin. The study found that the Dongwu movement at the end of the Early Permian was uplifting of fault block under tensional background. The Dongwu movement turned the southwest Kang-Dian ancient land into a provenance under the pushing and shoving by the ancient Tethys oceanic crust. Meanwhile,a trough graben area was formed in the northwest Guangyuan-Wangcang area due to the associated tensional subsidence. The relief in the area declines at low angle from southwest to northeast and indirectly controls the formation and lithofacies distribution of Wujiaping Formation. The sedimentary facies zones feature in wide and gradual variation. The Late Permian Wujiaping Formation was resulted from an high sea level transgression from northwest to southwest above the early weathering erosion interface. A denudation area and alluvial plain-coastal plaincoastal swamps-carbonate ramp sedimentary systems are successively developed from the southwest to northwest. Among these sedimentary systems,the moderate-shallow ramp bioclast beach was the most favorable reservoir facies belt with large thickness,wide distribution and near distance to the Guangyuan-Wangcang hydrocarbon kitchen,and it is capable of trapping hydrocarbons generated nearby. Several rounds of detailed digital seismic investigation have revealed many buried structures,providing new domains for enlarged exploration of carbonate gas reservoirs in the basin.

关 键 词：沉积体系 演化模式 吴家坪组 晚二叠世 四川盆地 

分 类 号：TE121.3[石油与天然气工程—油气勘探]