| Qikou depression is one of the prolific depression in Huanghua Depression, which is an important exploration area and layer system of the Dagang oil field.It has the features of the deep subside depth, the low degree of exploration,the plenty remaining resources and large exploration potential. It has the basic oil geology conditions of developing large oil gas field.During the exploration and development course of50years, the hydrocarbon accumulation research of Paleogene and Neogene in Qikou depression has gained a number of new understandings:the allocation between the multi-level slope break inherited developed in the depression slope area and many types of sand body is conducive to the formation of large-scale lithologic trap; the allocation between the synsedimentary faulting long-term developing in the prolific depression and the large sand body in slope area is conducive to the formation of multi-layer system overlapping oil and gas rich region; the hydrocarbon accumulation of Tertiary has many distinctive features such as continued buried, relay of hydrocarbon generation, episodic action, multi-stage charging, duplex folding oily;"Oil and gas are able to be transported into and trapped in it" is the main controlling factor of Neo-source/Paleeo-reservoir typed buried hill hydrocarbon reservoir formation just as "Oil and gas are able to be generated and preserved in it" is Paleo-source/Paleo-reservoir,which enrich and develop the petroleum geology theory of the Bohai Bay prolific depression.In this master’s thesis, based on the investigation of modern deposition and the ancient outcrop studies, the writer identified the simulated work area and mock objects to build a prototype model.Under the restraint of similarity theory, the writer established a scale model, designs detailed experimental arrangement. With continuously changing the water flow amount, the gravel input amount, the lake level and other parameters, besides adjusting the activity base plate, the writer obtained the formation, distribution and evolution regulations of braided river delta, fan-delta, gravity flow deposition sand body, which led to the qualitative understanding and quantitative relation under experimental condition,and finally completed this master’s thesis.This thesis achieved a multi-provenance hybrid flume experiment in China for the first time. The sedimentary simulation is reappeared in the laboratory of Shahejie Formation in Qikou depression Kongdian provenance braided river delta, Western Cangxian uplift fan delta and gravity flow prototype sand body in coastal regions. Synthesizing Paleogene ancient terrain, ancient landforms and regional basis geological data of Qikou depression, and generalizing respective depositional model of the sedimentary system provide office confirmation for oil and gas exploration guidance of Paleogene in Qikou depression. It clarifies the main controlling factors of braided river delta formation and evolution, including the basement subside, the relative lake level fluctuation, the rate of flow, the gravel input amount (provenance provided) and the flow rate of variation. Among which, the basement subside controls slope and tolerable room; the relative lake level fluctuation controls vertical and lateral delta distribution and distributary channel development; the rate of flow controls the distributary channel and sand body types; the gravel input amount (provenance provided) controls the deposition rate of the braided river delta; the flow rate of variation controls the extending and broadening rates of the braided river delta. The formation mechanism of sandstone distribution of the braided river delta area is discussed in this thesis. The gentle slope is geological background of large sandstone area; frequent sense of propriety of the lake level is the main controlling factor forming a large area of sandstones; strong currents is the necessary hydrodynamic condition forming a large area of sandstone; adequate source supply, high sand and mud rate are the material basis of forming a large area of sandstone; multi-river catchment is an important way to form a large sandstone area.The manners the sand body vertical stacked mainly include the mutual cutting between river and bar, and interaction of multi-provenance deposition. While the degree of sand body vertical stacked closely related to the relative lake level fluctuation, erosion of the river, vicissitudes of distributary channel, multi-provenance sedimentary interaction, basin subside and sedimentation rate matching. Morphological parameters of the bar and distribution are closely related to the incoming flow conditions. During the flood period, elongated vertical bars and digonal bars are the majority, whose average honst and kind rate is the minimum, while average aspect ratio is the maximum; during the dry season, the bars exposed, the large bars are the majority, whose average honst and kind rate is the maximum, while average aspect ratio is the minimum; during the period when a river is at its normal level, the crescent shaped, linguiform, diamond, elongated diagonal bars,vertical bars are developed well, the aspect ratio is between flood and dry seasons. The bedding type of braided river delta is abundance, and the lateral accretion cross-bedding and parallel bedding are common. On the cross section, lateral accretion cross-bedding is very obvious; on the longitudinal section, parallel bedding and cross bedding are relatively obvious, while the characteristics of the delta three-tier structure are obvious. In the intersection of fan-delta and braided river delta, the sand body is frequently cut, converged, and overridden, and the lenticular glutenite various in size and shape, at the same time, the directions are not the same.The Kongdian provenance braided river delta simulation experiments show that the basement subside, the relative lake level fluctuation, the rate of flow, the gravel input amount (provenance) and the flow rate of variation are the main controlling factors that impact Kongdian provenance braided river delta formation and evolution. While the low degree of slope, frequent sense of propriety of the lake level, strong currents, high sand and mud rate and multi-source supply are the main controlling conditions of sand body area distribution in Kongdian provenance braided river delta. Western Cangxian uplift provenance fan delta simulation experiments show that the fan-delta is a typical coarse-grained sedimentary system and by western Cangxian uplift obviously controlled. In general, it mainly has sandy conglomerate facies, mixed grain size, poor degree of sorting and psephicity and high clay content. It has features such as short deposition time, high deposition rate, high concentrations of sediment, rough grain composition and high clay content. Its sedimentation types are mainly braided channel deposition, debris flow deposition and overflow deposition.The experiments show that, Kongdian provenance braided river delta,Western Cangxian uplift fan delta and gravity flow prototype sand body in coastal regions have a good comparability with the experimental sand body thickness distribution. The average coincidence rate is respectively81.3%,78.1%and84.7%, and the total average coincidence rate is81.4%. It has a high coincidence degree and predicts respectively sedimentation types of favorable reservoir distribution area of the Shahejie formation in Qikou depression. |
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