| Guided by carbonate sedimentology, stratigraphy, carbonate petrology and other theories; taking geology, geophysical as methods and basing on identification of petrology character, sedimentary structure, this paper classified sedimentary microfacies and analyzed sedimentary facies distribution characteristics vertically and horizontally. Well-to-seismic method is used to classify the seismic facies and analyze the plane distribution characteristics of seismic facies. Combing with the achievements of sedimentary facies and seismic facies, this paper established sedimentary facies distribution patterns, and predicted favorable sedimentary facies belts.Strata of Lianglitage Formation in Tazhong area III are divided into5lithologic sections and12sublayers from top to bottom. From the analysis, most area lack layers of Liang4-Liang5section. The thickness of Lianglitage Formation is gradually increasing from south to north and west to east.There are open platform and platform edge facies mainly developed in research area. The open platform face can be divided into intrafacies such as platform interior grain bank, interbank sea, platform interior hollow, platform interior glacis and lime-mud mound. The platform edge facies also can be divided into intrafacies such as platform edge bank, interbank sea, lime-mud mound. In open platform, the dominant facies are interior hollow and interbank sea. The percentage of interior hollow and interbank sea are34%and28%.The interior grain bank and lime-mud mound account for17%and10%. Interior glacis accounts for13%.The platform edge bank is widely developed in platform edge, and this facies accounts for62%of total sedimentary facies in platform edge. The lime-mud mound facies is the second favorable facies, its proportion is23%. There are little interbank sea in platform edge, only takes15%. The study described the distribution of sedimentary facies in the lateral direction. The platform interior grain bank and lime-mud mound intrafacies have small scale and bad continuity. There are large-scale interior hollow and interbank sea with good lateral continuity in open platform.The platform edge bank is extensive development in platform edge facies, which is featured by large scale and strong scalability. There are some interbank sea of small scale between platform edge banks. The lime-mud mound are based on banks with a certain continuity.Seismic facies can be divided into seven kinds such as mounded shape, weak-Strong amplitude phase; mounded shape, high amplitude, middle continuous etc. The reflection with mound-like weak amplitude and sub-parallel continuous is associated with energetic banks. The reflection with middle-high amplitude is stand for interior hollow and interbank sea.The large range grain bank is mainly developed in the platform edge. A small quantity of grain bank is scattered between interior hollow and interbank sea. During the sedimentary period of Lianglitage formation, the sea level increased gradually and the water deepened. Thus, the amount of high energy bank gradually reduced, and the range of platform edge become more and more narrow, the number of interbank sea and platform interior hollow increased. At the same time, the range of open platform increased. Grain bank relatively developed in the third section of Lianglitage formation, and lime-mud mound mainly developed in the second section of Lianglitage formation, while, there are little grain bank in first section of Lianglitage formation.This paper enriched the sedimentary research in Tazhong area, and provides some geological guidance for the next step to oil and gas exploration. |
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