建南地区长兴期层序地层与沉积相演化

Sequence Stratigraphy and Evolution of Sedimentary Facies of Upper Perma in Jiannan Area

在建南地区长兴组沉积构造背景认识的基础上,针对沉积相与储层精细研究的需要,通过对关键层序界面的识别,并综合测井、岩性信息进行高精度的四级层序划分,将研究区长兴组划分为两个三级层序,5个四级层序,明确了建南地区四级层序地层格架内长兴期储层纵向发育部位及沉积相横向分布规律。将单井四级层序地层标定到地震剖面中并建立地震层序,通过引入地层等时切片技术,以四级层序格架内体系域为作图单元进行沉积相演化研究。结果表明,建南地区长兴组下部三级层序经历了3次海平面下降,高位体系域(HST)为主要的生物礁滩发育时期;上部三级层序主要以白云岩暴露滩体发育为主,规模明显小于下部三级层序,其分布范围有向研究区中部迁移趋势。

Based on previous researches of sedimentary structure of Changxing Formation,and combining with reorganization of sequence boundary,logging and lithology data,Changxing Formation in Jiannan Area has been divided into two three-order sequences and five fourth-order sequences,the development of reservoir and transverse distribution of sedimentary facies within fourth-order sequence in Changxing Formation have been studied in this paper. According to the calibration of fourth-order sequence on seismic section and time-slice map of strata,taking system tract of fourth-order sequence as mapping unit,the evolution of sedimentary facies is also discussed. The results indicate that the lower three-order sequence experienced three times relative fall of sea level,the organic reef and bank mainly developing in the stage of HST;in the upper three-order sequence,exposed organic bank with lithology of dolomite is widely distributed,but the scale is smaller than that of lower three-order sequence and the distribution range moves to the central part of study area gradually.