Study On Chang 6 Sedimentary Facies And Oil Enrichment Regularity In Hujianshan Area Of Erods Basin

Hujianshan-Zhoujiawan area is the important oil gengrative area in Ordos basin, and the subaqueous distributary channel of dealt front of Chang 6 developed very well. As the primary oil beds, the effective exploration and reasonal development of Chang 6 are significant for the development of Changqing Oilfield. In order to further study the rules of the hydrocarbon accumulation and distribution, exploration direction in the area, on the basement of sedimentary petrology and reservoir geology, using the combination of geology and well-logging, sedimentary system, micro-facies and the distribution rule of sand body have been studied systematically, and the favorable targets are selected in the end. This thesis has gained 5 studying results:1. Nearly 20 kinds of lithofacies have been identified by observing cores, the sedimentary facies in this area is dealt front, and it is composed of subaqueous distributary channel, subaqueous natural levee, subaqueous crevasse splay and subaqueous distributary sunken.2. Study on the sedimentary micro-facies shows that this area is river dominated delta which is affected mostly by river, and NE is the main direction of sediment provenance. Sedimentary environments of Chang 6₁, 6₂ and 6₃ subages have good inheritance, which make all the sandbodies of different time spreading in the NE-SW direction on the whole, and are obviously influenced by lake-level fluctuation.3. All of the micro-facies swinging and overlaying on the plane, and the general trend of the thickness of sand body varied from thin to thick and then to thin again. The subaqueous distributary channel developed very well.4. Based on the study of reservoir, lithologic reservoir is recognized as the mainly reservoir types of Chang 6 in this area. Oil-generating center controls the distribution of reservoir, and near-source accumulation is the mainly accumulation type of oil and gas .Micro- facies controls the distribution of favorable reservoir, and the favorable reservoir controls the migration and accumulation of oil and gas. Mudstones of subaqueous distributary sunken play the role of lateral sealing, structural high part of small nose uplift is helpful to the accumulation of oil and gas.5. Referring to the well testing and early production test data, and on the basement ofcomprehensive analysis with structure, sandstone thickness, porosity, permeability, etc,favorable exploration areas of Chang 6₂ and 6₃ are selected out in the end.