鄂西-渝东区长兴组礁滩体发现及相带分布

开江-梁平陆棚周缘的台缘相带是大型天然气藏发育的有利地区,陆棚相带的分布控制和影响长兴组-飞仙关组礁滩相带的展布。为了准确描述其分布,通过对岩心、岩屑、薄片等分析测试资料的研究,系统分析了岩石的颗粒结构、生物构成、结构类型等特征。利用三维地震资料对生物礁、滩体的形态及分布进行了预测。同时综合钻井资料、露头及地震资料精细刻画了长兴组沉积相带的展布。研究表明,箭竹溪生物礁是典型台地边缘相生物礁,具有明显的丘状外形、近南北向展布;在生物礁底部发育的浅滩白云岩分布范围较大,其主体位于箭竹溪生物礁的东部,与台地紧密相连;开江-梁平陆棚经过箭竹溪生物礁西侧向东南延伸与鄂西盆地相通,且箭竹溪生物礁与普光地区生物礁处于同一个台地边缘相带上。

New evidences of reefs,shoals and sedimentary facies of the Changxing Formation in Western Hubei and Eastern Chongqing area

Platform margin facies belts surrounding Kaijiang-Liangping continental shelf are favorable for the development of large gas field.The distribution of the continental shelf controls the distribution of reef and shoal facies belts.In order to accurately map the distribution of reef and shoal facies belts,the core,cutting and thin section data were integrated to systematically analyze the grain size,fossil composition and structure types.Moreover,3D seismic data were used to predict the appearance and distribution of the reefs and shoals,and the sedimentary faces in Changxing Formation were mapped by integrating drilling and outcrops data.The nearly NS-trending dome-shaped Jianzhuxi bioherm is of typical platform margin facies.The shoal-facies dolomite at the bottom of the bioherm is large in lateral distribution and its major part is located in the east of the bioherm and is closely interconnected with the platform.The Kaijiang-Liangping continental shelf extends southeastwards across the western part of the Jianzhuxi bioherm and is connected with to West Hubei marine basin.The Jianzhuxi bioherm is located in the same platform margin facies belts with that of the bioherms in Puguang areas.