| Based on the theory of petroleum geology, geochemistry, collect and summarize the predecessors’information and geological survey data as well as the representative of well core observation, we mainly do research about carboniferous-Permian hydrocarbon source rocks in Songliao basin. We have established oil and gas geochemical profile, and then launch a study of source rock control and oil control by tectonic system.Songliao basin spreaded as a diamond shape, and composed by six two-tectonic units, the direction of its long axis is north-east, the length of the basin is over 750 kilometers, and the width is over 330-370 kilometers, the area is about 26 million square kilometers. The base of Songliao basin is mainly composed by metamorphic and granite which come from Carboniferous-Permian.The overall level of exploration from Carboniferous-Permian in Songliao basin is not high. From now on, there are approximately more than 60 exploration wells drilled to Permian.The main hydrocarbon source rocks in permo-carboniferous of Songliao basin and other areas which are nearby have widely distribution area, and the hydrocarbon source rocks in the east of the basin are thicker than in the west. Four sets of hydrocarbon source rocks in the study area are mainly distribute in Dedu-longjiang, Yichun-Bindong, and central of Jilin marina, and the thickness differences are bigger.In the center of the basin, the carboniferous-Permian hydrocarbon source rocks have highly organic carbon content, the values of organic carbon distributed from 0.4% to 1.0%, some areas are over 1.0%, and overall evaluation for good to excellent hydrocarbon source rocks. On the edge of the basin outcrop area, the organic carbon content is low, the values of organic carbon are lee than 0.4%, some areas are even lower than 0.2%, and comprehensive evaluation for the poor-secondary hydrocarbon source rocks. So, the organic matter abundance in the center of the basin are better than on the edge. In terms of organic matter type, most organic matter tyoes are type Ⅲ, in the ceter of basin is tye Ⅱ,a small amount of type Ⅰ, on the edge of basin are mainly type Ⅲ, so, in the heart of the basin is better than the outcrop edge, Now the organic maturity generally higher than before, the value of Ro mainly distributed from 0.6% to 3.4%, the average is 2.23%, universally access to high-overripe stage, but it can also still be considered as valid source rocks.The conclution that character of dry asphalt from Paleozoic strata is familiar with saturated hydrocarbon parameters from Carboniferous-Permian source rocks indicat that dry asphalt of Permian comes from sources rocks of Permian.stratum.Structural system controls the formation and evolution of the basin, and thus determining the sedimentary basin characteristics and depositional environment controls the development of hydrocarbon source rocks. According to the source control theory point of view, the spread of Carboniferous-Permian source rocks controls the spread of oil and gas. So, structure system controls the source and oil. The Carboniferous-Permian strata of Songliao basin and source rocks are controlled by china structure system, china new structure system and zonal structure system. There is a lot of basement faults in basin and outlying areas, NNE-trending and NE-trending faults control the basin, under the control of basement faults, Late Paleozoic strata and sedimentary facies appear NNE and NE trending, thus, the spread of source rocks are also appear NNE and NE trending, at the same time, the distribution of oil and gas resources appear NNE and NE trending, The inversion structure formed by the joint of these control system is very favorable to Hydrocarbon accumulation. there can formed a traps when oil and gas enter the inversion structure, A lot of oil and gas from Songliao basin have relation with the inversion structure. So, the study of system control oil and gas have a lot of sense when discovering oil and gas. |
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