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在前人研究基础上,结合鄂西建南地区最新钻井资料和地震解释成果,详细解剖该区长兴组沉积相特征及礁滩体沉积演化模式,提出了长兴组沉积早期发育碳酸盐缓坡、中—晚期发育碳酸盐台地的沉积模式,其中台地模式包括镶边台地和孤立台地,礁滩沉积主要发育于台地边缘相带。建南地区长兴组礁滩分布特征研究表明,南部以滩相沉积为主、北部以礁相沉积为主,其中礁、滩沉积体均发育于各层序的高位体系域,尤以第1个三级层序高位体系域最为发育。该区礁滩沉积是在相对海平面不断下降的背景下发育的,形成了一套规模较大的加积—进积型台地边缘生物礁、滩沉积序列。主要礁滩发育期可分为3个演化阶段,第1阶段以小规模低能滩相沉积为主,也是生物礁奠基阶段;第2阶段为大型障积型生物礁和生屑滩发育期;第3阶段为生物礁逐渐消亡阶段,该期生物礁以黏结—障积型生物礁为主。礁滩发育晚期的暴露浅滩白云石化作用强烈,形成良好的储集岩。
Based on the previous studies and the latest drilling data and seismic interpretations in Jiannan area in western Hubei Province, the sedimentary facies characteristics of Changxing Formation and the sedimentary evolution patterns of reef banks are detailedly dissected. The carbonate sediments, The sedimentary model of the carbonate platform developed in the middle and later stages, in which the platform model includes the striped platform and the isolated platform, and the reef-beach deposition mainly develops in the facies margin of the platform. The distribution characteristics of reef banks in Changxing Formation of Jiannan area show that the southern part is dominated by beach facies sediments and the reef facies sedimentary mainly in the northern part. The reef and beach sediments are all developed in the upper system tract of each sequence, especially in the first The third-order high-level system tract is the most developed. Reef beach sediments in the area developed under the background of declining relative sea level, and formed a set of large-scale accretion-depositional reef and beach sedimentary sequences. The main reef beach development period can be divided into three evolution stages, the first stage of small-scale low-energy beach facies deposition, but also the reef reef foundation stage; the second stage for the large barrier-type reefs and broom beach development period; The third phase is the gradual disappearance of reefs, reef-bound bio-reefs dominated in this period. Exposed shoal dolomitization was intensive during late reef development, forming a good reservoir rock.