The Study On The Sedimentary Microfacies Of Dongying Formation In Liuchu Oilfield, Raoyang Depression

In order to get an even clear sight of the the source, the distributing feature and the control factor in the central southern part of Raoyang depression,this thesis has used Liuchu oil field as the study area and made a predictive study of sedimentary microfacies and favorable sandbody by synthesizing the datas relating to drilling,logging,geochemistry ,and seism in the period of the secongd-third member of Dongying Formation and analysis of information–based with the direction of sedimentological theory of seiscic stratigraphy..The Liuchu.Oilfield is a complicated block oil pool which is located at Shanwang faulted nose structure in the Liuchu structural belt of central southern Raoyang Sag Central Heibei Depression. The main facies indicators of the fluvial sandbodies habe been established based on the comprehensive analuses of core description ,correlation and division of stratigraphic intervals, individual sandbody microfacies and log facies description .the results indicate that during the deposiption of Member 2 and Member 3 of Dongying Formation . the Liuchu area was inated by the low-sinuosity braided fluvial facies . the main petroliferous sandbodies can be divided into fluvial channel , fluvial bank,oxbow lake and flood plain subfacies which are further subdivided into channel-bed lag point bar,natural levee,crevassesplay, overbank and flood plain microfacies. The river channels migrated frequently in the period of Dongying formation in Liuchu oilfield. There were several confluence of tributary rivers and deposited continues and thick sand body in the junction of main channels. In the period of the third member of the Dongying Formation, sand bodies with better oiliness were very developed and the main channels developed in borefild of Chu 28, Chu 29, Chu 39 and Chu 40. In the period of the second member of the Dongying Formation, the range of main channels became smaller, with the development of secondary channels, and the main sand bodies developed in borefild of Chu 28 and Chu 29. Riverbed lag deposits and shale filling in the streamthread, abandoned river filling beside the drainage line played roles of seal for oil-gas migration through contain oily analysis of sand body. Some sand body seemly in fine continuity actually was in different oil-water systems, and then it caused abnormal occurrence of oiliness in the lower part and water in the higher part。The adjustment of jection-production relation of petroleum reservoir can be made according to the internal heterogeneity of the sandbodies of different microfacies.It is also a reliable geologic foundation for petroleum field exploitation.The most important reservoir space in the study area was secondary secondary pore caused by the feldspar particle and carbonate cement dissolved and then with little tectonic cracks.The storage physical properties of reservoir in Ed2 were better than that of Ed3. Combining the sedimentary microfacies, the type of the rock,the storage space and the features of pore configuration,we have made a comprehensive evaluation of the reservoir in this area and divided the reservoirs in the study area into three types.The distribution of typeⅠis small,and is mainly developed in point bar by the edge of large-scale fluvial channel; TypeⅡis mainly developed by the edge of fluvial channel,and some in small-scale fluvial channe;TypeⅢis mainly developed in fluvial channels and crevasses play ,and widely spread.