| The differnence of Subsidence and Uplift in the petroltferous basin and their relationship with faults and fractures greatly influence on the formation of the oil and gas reservoir. At the present time, the research on it is scarce.In the paper, based on the analysis of deposition-subsidence features of the middle and upper part of the3rd member,the upper and lower part of the2nd member, the1st member of Shahejie formation, Dongying formation,Guantao formation,Minghuazheng formation and the Quaternary, and of the erosion feature of Dongying formation in Zhanhua depression, the differences in subsidence and uplift of the major hydrocarbon source rocks of Zhanhua depression (the upper part of the4thmember-the middle part of the3rd member of Shahejie formation) in the sedimentary period of the upper part of the3rd member,the upper and lower part of the2nd member, the1st member of Shahejie formation, Dongying formation,Guantao formation,Minghuazheng formation and the Quaternary were researched. The relation between the fault and the differences in subsidence is researched through the research of seismic datas, The relation between the development characteristics of crack and the differences in subsidence is analyzed through the observation of crack in the core of the Paleogene-Neogene in Zhanhua depression and the compression-elasticity-fracture experiments of rock. The difference of transport capability between the different transport mediums is compared on the basis of the the experimental results of permeability of porous and fractured rock. Based on the above research, combination with the analysis of the driving force for hydrocarbon migration, the forming characteristics of oil and gas reservoir related to fault and crack of the Paleogene-Neogene in Zhanhua depression are discussed.The main conclusion as follows:1. The subsidence center of the major hydrocarbon source rock mainly distributed near Bonan-Gubei and Fulin-Gunan areas in the sedimentary period of the upper part of the3rd member of Shahejie formation to the sedimentary period of, the1st member of Shahejie formation, the subsidence center mainly distributed near Bonan-Gubei,Zhuangxi and Gunan areas in the sedimentary period of Dongying formation to Quaternary. In the sedimentary period of the1st member of Shahejie formation the largest degree of subsidence was more than1200m; In the sedimentary period of Dongying formation, it was more than1800m in Bonan-Gubei and Gunan areas, than1300m in the Zhuangxiarea; It was more than2000m in the sedimentary period of Guantao formation and3400m in the Quaternary(the major hydrocarbon source rocks began to generate more oil and gas in the period). On the whole, the mainly distributed areas of the largest degree of subsidence were steady in the sedimentary period of the upper part of the3rd member of Shahejie formation to the sedimentary period of the1st member of Shahejie formation, but from the sedimentary period of Dongying formation to Quaternary, it migrated step by step to the southeast, the subsidence degree of the depression reduced greatly from the subsidence center to the northwest. The present area of the largest structural depth of the major hydrocarbon source rock were located in Bonan-Gubei, Zhuangxi and Gunan, and developed from the subsidence of the sedimentary period of the middle part of the3rd member of Shahejie formation.2. The fault could be divided into two types based on the relation between the fault and the area of the largest structural depth. Along the fault strike, the first type is that the fault dug in the area of the largest structural depth or intersected the structural contour, the second type that the fault did not dig in the area of the largest structural depth and approximately paralleled the structural contour.3The burial process of stratum could divided into three phase:compaction phase, elastic-plastic compression phase, fracturing phase. In the Paleogene-Neogene formations of Zhanhua depression, there are parallel crack, vertical crack and oblique crack in sandstones and mudstones, some parallel cracks have the slipped features that greatly existed in mudstones. The main kinds of crack complex are "gong" or "T". In Zhanhua depression the crack developed in the mud rock which burial depth is more than2000m. In the development of Zhanhua depression, the different extension capability between zhe different rocks in the parallel direction is the mainly reason for the formation of parallel crack. With the increase of the pressure caused by the overlying rock, vertical crack would occur in the rock due to the restriction of the extension capability of rock in the horizontal direction. When the vertical pressure is unbalanced, the oblique crack would easily occur in the rock. When the uplift occurs in the basin, it would induce the development of the crack in the rock, lead the crack developed in the period of subsidence of the basin to expand, and cause he burial depth of the rock which the crack developed in to shallow4The area of the largest driving force for hydrocarbon migration in the main hydrocarbon source rock are distributed near Bonan-Gubei,Zhuangxi and Gunan, controlled by the subsidence degree and formation temperature of the main hydrocarbon source rock and corresponded with the area of the largest burial depth of the main hydrocarbon source rock in the key geologic period. The driving force for hydrocarbon migration greatly reduced from the area of the largest driving force to the around. In the porous rock, the parallel permeability is greater than the vertical (Parallel permeability is6.62-398.77times of vertical permeability in mudstone, average220.79times; parallel permeability of sandstone is1.05-7.17times of vertical permeability, average4.72times). The permeability of fractured rock is greater than the permeability of porous rock(Fractured mudstone permeability is1.35-21000times of porous mudstone, average2729.17times; fractured sandstone permeability is1.17-178.57times of porous sandstone, average29.49times.). The pathway system of hydrocarbon of the Paleogene-Neogene in Zhanhua depression was divided into two types. One type is related to the crack and mainly constituted of porous and fractured rock, and could be divided into the non-fracture developing belt and the fracture developing belt on the basis of the2000m of burial depth. Another type is related to the fault. and mainly constituted of all kinds of faults, according to the burial depth feature of the fault top along the strike of fault, this type could be divided into the plunging fault and the horizontal fault pathway system of hydrocarbon.5. In the Zhanhua depression, the forming process of oil and gas reservoir related to crack, as the action of the largest driving force in the hydrocarbon source rock, oil and gas mainly migrates along the crack, and finally entrances into the trap. According the migration resistance difference between oil, gas and water, the oil and gas reservoir would form with the increase of saturation of oil and gas in the reservoir and. The oil and gas reservoir related to the crack is mainly distributed in the developing crack belt, it is hard to form the oil and gas reservoir in the non-developing crack belt. In the forming process of oil and gas reservoir related to fault, oil and gas migrates along the fault, buoyancy-driven hydrocarbon easily float up to the top of the fault, assembles the top of the fault, and finally gathered in the adjacent traps and reservoir. The oil and gas reservoir distribution is related to the burial depth feature of the fault top along the strike of fault. If the fault top is plunging, the oil and gas reservoir is mainly distributed in the trap and reservoir adjacent to the fault peak; if the fault top is horizontal, the oil and gas reservoir is mainly distributed in the trap and reservoir adjacent to the fault along the strike of fault.6. In Zhanhua depression, in the process of the exploration of oil and gas reservoirs related to the crack, the favorable oil and gas distribution on the plane is mainly located in the range that the burial depth of the hydrocarbon source rock is more than2000m, in the vertical, the oil and gas exploration should start from the main source rocks for the bottom line, from deep to shallow, the attention should be paid to the sandbody located in or adjacent to the source rocks and the crack belt of madstone. in the process of the exploration of oil and gas reservoirs related to the fault, for the fault which top is plunging, the favorable oil and gas distribution is mainly located in the area of the fault peak; for the fault which top is horizontal, the favorable oil and gas distribution is mainly located in the both sides of the fault along the strike of fault. |
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