【作者】 古俊林；

【导师】 阳正熙； 罗平；

【作者基本信息】 成都理工大学 ， 矿物学、岩石学、矿床学， 2004， 硕士

【摘要】 川西坳陷南部侏罗系地层是该区重要的产气层位，已经发现和投入勘探、开发的大、中型天然气田有十几处，具有巨大的勘探、开发潜力。但同时，浅层勘探效益与风险并存。川西侏罗系地层属红色陆相碎屑岩沉积，砂岩沉积在纵、横向的厚度、分布范围变化大，研究程度低，增大了勘探难度与风险。本文在详细的野外露头、岩芯观察的基础上，结合测井和地震剖面资料，对川西侏罗系地层进行了较为系统的高分辨率层序地层学研究。 研究区侏罗世蓬莱镇期沉积盆地的沉积相类型分布，从盆缘近物源区至盆地沉降-沉积中心区依次为冲积扇、河流相、扇三角洲相、河控三角洲相、湖泊相和湖底扇相等沉积体系。本文对各沉积体系的特征进行了详细分析。 考虑到层序的发育同时受构造、气候、物源、A/S值变化和地层的自旋回过程等多种因素控制的特点，结合A．T．Cross按基准面旋回级别划分层序和层序命名的原则，提出同时考虑界面性质、界面级别、层序结构和叠加样式的超长期、长期、中期和短期4个级别的层序地层综合划分方案，将研究区侏罗系地层划分为：4个超长期旋回层序，8个长期旋回层序，22个中期旋回层序及百余个短期旋回层序。讨论了短期基准面旋回层序的各种结构类型和沉积动力学过程与地层响应的关系。 本文采用小尺度地层单元的等时追踪对比方法，对研究区侏罗系中相当于中期旋回层序中的中、小层尺度地层单元进行了等时追踪对比。对重点层系(侏罗系上统蓬莱镇组和中统沙溪庙组)进行高分辨率层序地层学编图，揭示曲流河三角洲砂体的连续性及分布规律。 以长期基准面旋回层序为骨架，以中期基准面旋回层序为单元进行等时对比，建立研究区的等时地层对比格架，并对长期旋回层序在层序地层格架中生、储、盖组合特征进行分析，更为清晰地揭示和描述有利生、储、盖相带的时空展布与演化规律，为提高油气勘探和开发的成功率提供有效的地质依据和信息。更多还原

【Abstract】 The Jurassic of West Sichuan depression are important natural gas productive strata,wher dozens of large or middle gas fields have been found with great exploration and development potential. However, in the shallow stratum, exploration profits and adventures coexist. With greatly changed thickness of the beds and with little research work done, it is difficult and risky for gas exploration in the Jurassic. In this paper, on the basis of detailed outcrop and core observation, as well as the logging and seismic data, the high resolution sequence stratigraphy method has been applied to the West Sichuan Jurassic strata systematically.The sedimentary facies of the Jurassic Penglaizhen Formation in the studied area can be described as follows: from the edge of the basin, the source of deposition, to the center of the sedimentation are alluvial fan facies fluvial facies fan delta facies delta facies lake facies and lake floor fan facies in turn. The characteristics of each type of the deposition systems have been analysed in details in the paper.As is known, the sequence development can be controlled by many factors, such as structure, climate, source of deposition, A/S variation, and stratum self cycle process and so on. Taking these factors into account, and referring to the cycle grading method and naming rule according to base plane given by A.T. Cross, this paper has provided four grade sequences classifying synthetic plan, which has considered sequence boundary characteristics, boundary grades, sequence structure and superposing style. The classifying plan includes: super long, long, middle and short cycle sequence. On base of this plan, the Jurassic sequence of the studied area can be divided into 4 super long cycle sequences, 8 long ones, 22 middle ones and more than 100 short cycle sequences. In this paper, various types of structure and the relationship between sedimentary dynamic process and strata response of the short cycle sequences is discussed.Applying small scale strata units tracking and correlation method, the middle to small strata units of the Jurassic middle cycles in the studied area has been tracked and correlated in this paper. For the significant strata, the upper Jurassic Penglaizhen Formation and middle Shaximiao Formation, high resolution stratigraphy map making has been carried out, and the continuity and occurrence of the meanding stream delta sand body has been discovered.Regarding the long base-level cycles as skeleton, the middle ones as correlation unit, the stratigraphy framework of the studied area has been constructed. By analyzing the significance of the long base-level cycles in the stratigraphy framework,source, reservoir and cap has been revealed and described more detailedly, the time and space extent and involvement rule of which has become more clearly. Thus, effective geological evidence and information can be provided, and petroleum exploration and development efficiency be improved accordingly.更多还原