Abstract: There are many sets of fluvial facies sandbodies developed in the upper Guantao Formation in Chengdao Oilfield,and the connectivity between the sandbodies is different,resulting in uneven injection and production in the study area. The upper Guantao Formation of Chengdao Oilfield has the characteristics of many high angle holes,large well spacing,rapid change of sandbodies,and limited ability of seismic data to identify single sandbody. On the basis of well-point analysis,a comprehensive identification was carried out combined with wave equation forward modeling and geostatistical inversion,and five configuration models of fluvial sandbodies in Chengdao Oilfield were established. They are separation type and composite superimposed type in vertical and separation type,river bank contact type and cutting and stacking type in lateral. In the vertical direction,the separated channel sandbodies have good connectivity,while composite superimposed sandbodies that are not connected are cut and overlapped between upper and lower layers,with ineffective water injection and rapid production decrease. In the lateral direction,the separated sandbodies are basically disconnected;the river bank contact sandbodies are poor in connectivity and slow in effectiveness;two-stage channel sand bodies of the cutting and stacking type are partially superimposed,and sandbodies with large cutting and stacking thickness have good connectivity,with quick water injection efficiency,while sandbodies between two single channels with small cutting and stacking thickness have poor connectivity. The results provide a basis for realizing balanced injection and production in oilfields.

Key words: channel sandbody, superposition type, wave equation forward modeling, geostatistical inversion, Guantao Formation, Chengdao Oilfield