Sedimentary Sedimentary Environment And Favorable Area Analysis Of The Lower Carboniferous Yanguan Formation In The Central And Northern Guangxi Region

In this paper,on the basis of previous studies,through field profile measurement and identification of rock thin slices,palaeontology identification,scanning electron microscopy analysis,X-diffraction analysis,whole rock total organic carbon content(TOC)analysis,kerogen(Ro)analysis and other laboratory analytical skills,we analyze the Guangxi in northern(focusing on the northern part of Nanpanjiang)Carboniferous rocks.Sedimentary facies,organic rich shale reservoir,organic geochemical characteristics and prediction of favorable areas of shale gas.First,on the basis of the measurement of typical field profiles,according to the lithology and paleontological features,the stratigraphic division of the research horizon is carried out.Then,by identifying the sedimentary facies marks of the search area,we divide the sedimentary facies types,and draw the single profile sedimentary facies comprehensive column and multi profile sedimentary facies contrast map,and combined with the lithofacies plane distribution characteristics,we complete the plane distribution analysis of sedimentary facies.Finally,we carry out the research on the thickness and distribution of organic shale,shale reservoir characteristics,geochemical characteristics and preservation conditions of shale gas,establish the evaluation criteria of shale gas favorable area,and predict the favorable area of shale gas in the study area.In the early stage of early Carboniferous(C1),due to the influence of the main act of the Ziyun movement(the second act of the Ziyun movement),the strata in the ascending disk of the active fault began to undergo a wide range of uplift.The depositional pattern is basically a continuation of the Devonian platform-basin sedimentary palaeogeographic pattern,in addition to along the fault zone(mainly the Ziyun-Luodian fault zone),which is characterized by a large number of provenances in the strata of the active strata.Except that the area along the fault zone is the continental shelf,the other most of the regional sedimentary facies for the limited platform or open platform.In conclusion,the thickness of the shale in the target areas is greater(the maximum cumulative thickness of up to 300m above),the abundance of organic matter is high(organic carbon content of 1.53%-5.57%),the degree of thermal evolution of the kerogen is moderate(vitrinite reflectivity of 1.54%-3.05%),the storage space of shale gas and storage conditions of shale are relatively good.The Lower Carboniferous rocks in the study area have a large potential for exploration.Based on the experience of exploration and development of shale gas in North America,combined with the practice of shale gas exploration in southern China,the relevant indicators of favorable area evaluation are discussed.It is believed that Tian'n-Nandan-Hejiang-Luocheng area is the Lower Carboniferous in the northern depression of Nanpanjiang is the favorable area for shale gas exploration,the Qinglong-Ziyun area and the Luodian-Wangmo-Tian'e-ring-Luojiang area are relatively favorable areas for shale gas exploration.