The Distribution And Sedimentary Environment And Its Oil - Gas Exploration Potential In The Middle And Upper Paleozoic In Ordos Area

With the Meso-Neoproterozoic reservoirs found in the abroad and domestic, especially he discovery of the asphalt in the southwestern margin of erdos basin and the natural gas of Changcheng syetem in Yimeng Uplift, making the Meso-Neoproterozoic is becoming a concern potential filed in Ordos Area. The Ordos area is located in the west part of the North China Craton, and the Meso-Neoproterozoic unconformity on crystalline basement, which consolidated in Lvliang movement. The Meso-Neoproterozoic are widely distributed, with no obvious deterioration. However, oil and gas exploration in the past focused on the Mesozoic and Paleozoic, and little researches on the Meso-Neoproterozoic, result in the weak of little research. To figure out the oil and gas exploration potential in Ordos area,based on sorting, summarizing the results of previous studies on the system, through field investigation, and profile measured, supplemented by analysis of test date, combined with logging, drilling core and the latest seismic profile and gravity and magnetic date, the classification and distribution of stratigraphic features, the Meso-Neoproterozoic sedimentary facies and their evolution in the study area are comprehensively studied, and predict the favorable exploration potential areas. Achieving the following understanding:(1) Based on the analysis of results of zircon U-Pb ages of the test and the previous, determining Huangqikou formation, Ruyang group, Haiyuan group belongs to Changcheng syetem, and wangquankou formation belongs to Jixian formation, and make the scheme in the Meso-Neoproterozoic of the Ordos area, draw the distribution map of Changcheng syetem, Jixian formation, and Zhendan formation.(2) The use of well logging, seismic and geochemical testing data, and combined with filed observation, microscopic identification results, the sedimentary facies and sedimentary environment of the Meso-Neoproterozoic was analyzed. The results showed that the environment of Xionger group for shallow-bathyal sea, Gaoshanhe group for tidal flat facies, Huangqikou formation for coastal-lagoon facies, Luonan group and Wangquankou formation for carbonate platform tidal flat facies, Baishugou formation for coastal-shallow marine shelf facies, and Luoquan formation and Zhengmugan group for coastal-glacial deposition.And ambinedir with the tectonic movement the sedimentary evolution of the western and southern margin of Ordos is analyzed.(3) According to evaluation standard, and combined with the organic geochemical analysis of test data, the hydrocarbon source rocks of the Meso-Neoproterozoic and the favorable areas were evaluated:the source rocks with mudstone of Changcheng syetem and Zhendan formation are poor, there are certain hydrocarbon generating potential. The hydrocarbon source rocks with marine carbonate of Jixian formation are poor-medium, have some hydrocarbon generating potential. The source rocks with mudstone of Baishugou formation is non-hydrocarbon source rocks. Combining the distribution and reservoir combination analysis in the Meso-Neoproterozoic, the favorable exploration potential areas are divided into three class:the oil and natural gas come from other stratum and stored in the Meso-Neoproterozoic, the oil and natural gas derived from source rocks of Jixian formation and reserved itself, the last, it both generated and stockpiled in the Meso-Neoproterozoic.