Analysis on the Theory and Practice of Petroleum Exploration Geology in Ordos Basin

The Ordos Basin is a large inland depression basin.The basin is surrounded by highland denudation zones.The water system extends to the lake basin, forming multiple sets of river-lake phase terrigenous clastic sediments.The lithofacies belt is alluvial from the edge of the basin to the interior of the basin.Phase, braided river, braided river giant angle continent and lake phase, the upper phase of the plane is obviously ring-shaped, and the asymmetry is distributed around the deep lake area.Because the northern terrain is flat, the phase belt is wide, and the southern part is steep due to the topography.The belt is narrower.The Upper Triassic Yanchang Formation in the Mesozoic in the Ordos Basin is rich in petroleum resources.With the continuous development of exploration technology, the average annual growth rate of proven petroleum reserves and oil production in the Ordos Basin is far ahead of other major basins, exploration and development.The potential is huge.The paper mainly discusses the theoretical and practical issues of petroleum exploration geology in the Ordos Basin. OverviewThe Ordos Basin is a large-scale intracontinental superimposed basin on the base of the Paleozoic craton shallow sea platform in the Mesozoic and Cenozoic basins.It is located at the intersection of several tectonic stress fields, and the stresses are mutually reduced and balanced, and the internal structure is relatively stable.It has developed seven major tectonic units such as the Jinxi Tangle Belt, the Yishan Slope, the Tianhuan Depression, the Western Edge thrust belt, the Weibei Uplift and the Yimeng Uplift.The oil and gas fields discovered today are mainly distributed in the Yishan Slope and the Tianhuan Depression.The Mesozoic in the Ordos Basin is a typical large inland depression basin with stable sedimentation, wide basin and large sedimentary range.In the early Late Triassic, it entered the lake basin development stage and developed a river-delta facies-lake.Phase clastic rock deposits, due to the abundant supply of resources, coupled with the stable return of the lake basin, deposited a set of lake-delta fractal rocks with a thickness of about 1,000 meters.The reservoirs of the Triassic Yanchang Formation are mainly controlled by high-quality source rocks and large-scale reservoir sand bodies.By continuously summarizing and deepening the reservoir-forming characteristics of low-permeability lithologic reservoirs, the model of the main development of the meandering river delta is prolonged.The model of the Meandering River Delta is: the sedimentary system in the northeast of the basin is the Meliuhe delta deposit, the reservoir is distributed along the main sand belt of the front of the meandering river delta, and the underwater distributary channel sand body is the main reservoir.Oilfield and Jing'an Oilfield are represented.The braided river delta is a model of reservoir formation: the sedimentary system in the western part of the basin is a braided river delta deposit, and the reservoir is controlled by the sand body of the braided river delta front, which is distributed in a strip shape, represented by the East-Western Mine.Multi-layered composite accumulation model: the northwestern part of the basin is located in the hydrocarbon-generating center.The thickness of the source rock is large, and the reservoir sand body develops vertically.Under the effective combination of abnormal pressure and various transport systems, the vertical layer is formed.The scene of compound oily is represented by Jiyuan Oilfield.The reservoir formation model in the central part of the depression: the reservoir is mainly controlled by the delta front and the gravity-flow composite sedimentary sand body, showing a large area distribution, represented by Huaqing Oilfield.Tight oil