渝东—鄂西地区黄龙组层序—岩相古地理研究

Sequence-Lithofacies Paleogeographic Study on Huanglong Formation in Eastern Chongqing Western Hubei Area

渝东—鄂西地区由于受海西早期强烈构造隆升和侵蚀作用影响,大部仅残存不完整的上石炭统黄龙组,为川东地区天然气藏主要产层,也是盆地周边地区寻找新气源最有利层位之一。根据岩心观察、野外剖面实测和室内镜下岩石薄片鉴定分析,并结合岩石学、古生物及测井等沉积相标志研究,确定该区黄龙组发育萨勃哈、有障壁海岸、海湾陆棚和开阔陆棚等沉积相带,连接川东—渝北海湾与鄂西广海海水通道的发现对区域沉积相带的认识具有重要意义。在层序地层学分析的基础上,以LST、TST和EHST三个体系域作为编图单元,编制了各体系域的岩相古地理图并对其演化特征进行了描述。结合各相带储集物性特征,认为障壁粒屑滩和滨外粒屑滩为最有利储集相带。

Due to intensive tectonic uplift and denudation affection in early Hercynian,the majority of the study area only keeps unsound Huanglong Formation of Upper Carboniferous in Eastern Chongqing-Western Hubei area.The Huanglong Formation is one of the most important natural gas reservoirs in the eastern Sichuan area and one of the most favourite horizons for exploring new gas sources.Based on core description,measured crosssection and thin section analysis,and combined with sedimentary marks of lithology,palaeontology,logging analysis,and so on.,the Huanglong Formation is divided into four main sedimentary facies： sabkha,beach-barrier coast,gulf shelf and open shelf.During the field investigation,passageway of sea water connecting the gulf of the eastern Sichuan-northern Chongqing with open sea of the western Hubei has been found,which has important meaning to furthur understand the regional sedimentary facies.On the basis of sequece stratigraphy,and used the three system tracts： LST,TST and EHST as the maping units,three paleogeographic maps have been mapped and lithofacies paleographic characteristics of each system tract has been described.Combined with the reservoir characteristics of all sorts of sedimentary facies,the barrier grain beach and offshore grain beach are thought to be the most favourite reservoir facies.