四川盆地高石梯--磨溪地区下寒武统沧浪铺组沉积特征

近年来,川中高石梯—磨溪地区特大型海相碳酸盐岩整装气田的发现揭示了下寒武统具有较大的勘探开发潜力,不同于主要目的层龙王庙组的是沧浪铺组的石油地质基础研究,尤其是沉积相研究十分薄弱,因此,有必要对该区沧浪铺组沉积特征展开研究。以层序地层学、沉积学、测井地质学等理论为指导,综合岩心、钻井、测井及薄片等多种资料,对高石梯—磨溪地区沧浪铺组沉积特征进行了研究。结果表明:沧浪铺组岩性自下而上呈碎屑岩-碳酸盐岩-碎屑岩-碳酸盐岩组合的变化规律;该组发育碎屑滨岸—陆棚、碳酸盐缓坡和风暴沉积等3种沉积模式,陆棚、内缓坡等2种沉积相以及混积浅水陆棚、浅水陆棚、混积潮坪、潟湖和浅滩等5种沉积亚相;沧浪铺组沉积期研究区以陆棚相沉积为主,自下而上呈浅水陆棚—混积浅水陆棚—浅滩—混积潮坪—浅水陆棚—混积浅水陆棚—混积潮坪的沉积亚相演替规律。该研究成果为高石梯—磨溪地区下一步下古生界油气地质基础研究及优质储层的分布和预测提供了参考。

Sedimentary characteristics of Lower Cambrian Canglangpu Formation in Gaoshiti-Moxi area,Sichuan Basin

In recent years,the discovery of the extra-large integral marine carbonate gas field in Gaoshiti-Moxi area in central Sichuan province has revealed that the Lower Cambrian has great potential for oil and gas exploration and development. Unlike Longwangmiao Formation which is of the main target in this area, the study on petroleum geological basis of Canglangpu Formation is still rather weak,especially on the subject of sedimentary facies. Therefore,it is quite essential to do study on the sedimentary characteristics of Canglangpu Formation in this area. Based on theories of sequence stratigraphy,sedimentology and logging geology,the sedimentary characteristics of Canglangpu Formation in Gaoshiti-Moxi area were studied by combining the data of coring,drilling,logging and core cuttings analysis as well. The results show that the lithology in Canglangpu Formation shows the change law of clastic rock-carbonate rock-clastic rock-carbonate assemblage from bottom to top. There are three sedimentary models developed in Canglangpu Formation,including detrital shore-shelf,carbonate gentle slope and storm deposit,two types of sedimentary facies,including shelf and inner gentle slope,and five types of sedimentary subfacies,including mixed shallow water shelf,shallow water shelf,mixed tidal flat,lagoon and shoal. There is mainly continental shelf facies in Canglangpu Formation,and there presents the sedimentary subfacies succession law of shallow water shelf-mixed shallow water shelf-shallow beach-mixed tidal flat-shallow water shelf-mixed shallow water shelf-mixed tidal flat. The research results may provide a reference for the further study on Lower Paleozoic petroleum geology and distribution and prediction of high-quality reservoirs in GaoshitiMoxi area.