Optimization Of Favorable Areas In PI Reservoir Group In ZS6 Well Block, Songliao Basin

As one of hydrocarbon enrichment areas in Sanzhao depression,ZS6 well block is structurely located in the east of Zhaozhou nose structure in Sanzhao depression,central depression area in the north of Songliao basin.And its area is about 30km~2.Aiming at the problems of complex structure,thin reservoir development,high risk of exploration and development,and unclear favorable blocks,the paper use the existing seismic data,geological and oil and gas test data,mainly through the fine structure interpretation,sedimentary microfacies and reservoir sand body prediction research to strengthen the understanding of underground geological features,and combine the main control factor of the reservoir to select favorable blocks.Using the 3D seismic data body for fine structure interpretation,it is clear that the oil layer is the lowest in the northeast and it buried deep between-1380~-1305m.The fault in the well block is a series of high Angle normal faults.And the north-south trending faults of Yanshanian period are cut into a grid by the east-west trending faults of himalayan period,and the smaller faults are scattered in the grid.Combined with regional sedimentary facies analysis results,the study of sedimentary facies were carried out by using well logging data.And it is clear that a major underwater distributary channel was developed in the well area,and branch channels were formed in the middle area.Mouth bars were developed in the bifurcation part of the channel,and sheet sands were widely developed.From PI5 to PI2,the underwater distributary channel gradually develops to the south and west,and the early stage is transgressive,the later stage is regressive.Based on the attribute analysis technique,the sand prediction is carried out using model-based inversion techniques by STRATA software.It is found that the overall thickness is thinner,and has a zonal distribution along the source direction.The predicted results are in good agreement with the actual drilling results.The sand body has the maximum thickness of 10m,the minimum thickness of 5.5m and the average thickness of 7.8m.The development of sand body is better than that in the east,and it is presumed to be the result of the gradual westward migration of the channel.By analyzing the main control factor of the reservoir such as source-reservoir-cap assemblage and passage system,according to the feature of structure,oil test data and sand body prediction result,three class I favorable areas and two class II favorable areas are selected,which are basically distributed in the western and central part of the working area.