Characteristicsof The Organic-rich Shales Of The Wufeng-longmaxi Groupin Wulong,southeastern Sichuan

This paper takes the shales of Upper Ordovician Wufeng-Lower Silurian Longmaxi in Wulong,sourtheastern Sichuan for the study and selects typical outcrop and adjacent areas of Wulong to measure the profile,description and sample the collections.And through the means of microscopic flakes,X-ray diffraction whole rock analysis,geochemical analysis means,for example:organic carbon,pyrolysis, chloroform bitumen,cheese with carbon isotopes,organic elements and asphalt reflectivity from petrology, sedimentology, geochemistry features and other aspects of the Wufeng-Longmaxi shale types,sedimentary facies distribution development characteristics,organic geochemical study and understanding to achieve the following outcomes:Through the field observation, thin section identification and X-ray diffraction, whole rock analysis five mountains-the dragon stream group black shale in the study area can be divided into four types:(1) black carbonaceous shale, dirty hands, mainly distributed in the text at the bottom of the group;(2) black, colored siliceous shale, including petrochemical stone, big thickness, high hardness, the main development in the upper text group;(3) the black shale, mainly distributed in the lower stream group, the dragon with pen petrochemical stone;(4) the silty shale, the main development in the upper creek, the dragon group. Shale mineral composition is given priority to with quartz and clay mineral, followed by sodium feldspar and microcline, individual sample see dolomite, calcite, pyrite, clay mineral is given priority to with mica, followed by illite and gypsum.According to rock types, sedimentary structure, sedimentary rock combination phase marker analysis and so on, in this text- the dragon stream group can be divided into two categories, shallow shelf and deep-water shelf sedimentary facies, shale types are controlled by sedimentary facies. The text is set mainly for a set of mixed deep-water shelf facies, lithology is mainly for the siliceous rocks and carbonaceous shale, local for siliceous shale and sedimentation of sand shale interbed; Dragon stream set lower for a set of argillaceous deep-water shelf facies, lithology is mainly for the black shale, local sand mass, the transition to sand upwards argillaceous shallow shelf facies, lithology is given priority to with silty shale.By observing outcrop and drilling data collection combined organic organic carbon content of the test data,and the vertical plane distribution development features a comprehensive analysis.Forming a series of ridges and furrows on the plane features, black shale thickness distribution and organic matter content with the following rules:(1)parallel ridges and furrows were affected by migration control and foreland basin with the long axis parallel to the plane of the foreland basin;(2)according to the thickness of the black shale thickness can be divided into two large regions were Jiaoshiba-Huangying–Bayu-Guanyinqiao(A band), Qiliao-Pengshui-Xiushan(B band).(3)a higher organic matter content of the region mainly focus Jiaoshiba-Huangying-Bayu-Guanyinqiao line, consistent with larger areas of sediment thickness, the area away from Sichuan uplift and uplift are far Qianzhong,and is the Wufeng-Longmaxi settlement center,the depth of water is relatively deep,is conducive to preservation of organic matter.The use of geochemical methods,research summarized abundance of hydrocarbon source rocks,organic parent material type and depositional environment and maturity of organic matter.Each profile Wufeng-Longmaxi shale organic matter content is high,0.55% to 10.38%,of which organic matter content value coke Jiaoshiba-Huangying-Bayu-Guanyinqiao area mainly from west to east as a whole showed a reduced organic matter content trend.Microscopic analysis of organic composition, family composition and kerogen δ13Corg reflect Wufeng-Longmaxi black rock sedimentary parent materials such as low plankton algae-based sapropelic source rocks,Longmaxi period began mixing a small amount of plants.Kerogen δ13Corg analysis Longmaxi typeⅠorganic-based,compared with the beginning of a large number of Wufeng Ⅱ1 type.Organic steroid terpane,aromatics markers and Pr/Ph analysts believe that the parent material source rocks formed in a certain salinity of seawater,the overall environment for a strong reduction of water depth,and the country vary.Equivalent vitrinite reflectance of 1.15% to 3.06%, with an average 2.01%, H/C is 0.52 to 0.65,most samples to achieve high maturity,some for over a mature stage.Comprehensive petrological characteristics, sedimentary facies and organic geochemical analysis, such as ChuanDongNa wulong district five mountains- the dragon stream set of black shale favorable development zone as the lower part of this text and the dragon kai group, favorable development zone for coke, wulong area of Jiaoshiba, Huangying matter content is more than 2% generally, organic matter type is good, high thermal evolution degree and high brittleness, good prospects for shale gas resources.