Sedimentary Microfacies Study Of The Yang Da Cheng Zi Oil Reservoir In Block X,Southern Songliao Basin

The Yang Da Cheng Zi oil layer is a secondary oil-bearing layer in the X block.With the gradual development of reservoir geology,the oil layer gradually highlights the mining value.The oil layer was not taken as the focus in the early development stage.The main target layer of the block is the Fu yu Reservoir,and the depth of well position in X block is relatively shallow.However,most wells were not completely drilled through the Yang Da Cheng Zi oil layer.Currently,the data are enough to understand the distribution characteristics of the reservoir.What's more,there is no detailed reservoir description for the X-block,which makes it an urgent to guide the theoretical system of sedimentary microfacies.This paper aims at revealing the fine division and comparison of small layers in the study area by a couple of approaches.The main method is combing the small layer contrast label registration horizon and multiple contrast modes and layer flattening techniques.Thus,the confusion of the naming of the Yangtaicheng sub-oil reservoir group was solved.By combining the characteristics of heavy minerals and comparing the contour maps of sand thickness and ratio of the sand and formation,it was found that the study area was affected by multiple sources,of which the southwest direction Tongyu-Baokang sedimentary system was the main source of material.Through a comprehensive analysis of single-well data of coring wells,the Yangtaiczi Formation in Block X was suggested to be an in a meandering river phase combined with various phase markers such as rock type and sedimentary structure.Block X mainly develops microfacies such as riverbed retention,point bars,natural embankments,crevasse fans,and floodplains.To establish the microfacies pattern of the 6 sub-layers 8 sedimentary time units of the meandering river in this area,the analysis of logging data from 88 wells was adapted.It was found that there were 3-5 bifurcations in each small layer of the study area.The number and sinuosity of the river channels were both relatively large.And the hydrodynamic force was relatively strong.The floodplain was well developed in the cross-section and the sand bodies of the rivers are enclosed in it.Sedimentary microfacies can effectively control the distribution of sand bodies.The sand body extended from the southwest to the northeast distributed in strips,which was controlled by the extending direction of the rivers.Therefore,the reservoir properties of different microfacies are distinctly different.The small sand bodies of 16 and 19 layers in the study area have high drilling rates,and the sand bodies distribute continuously.They have a stable sedimentary environment and are predominant reservoirs with high development value.Thus this layer has great potentialities to replace the Fuyu oil layer in the later stage of the oilfield development.