Reservoir prediction in a development area with a high-density well pattern using seismic sedimentology: An example from the BB2 block, Changyuan LMD oil field, Songliao Basin, China

摘要

The Daqing Changyuan oil field is primarily composed of large, fluvial-deltaic thin sandstones and shales with a high degree of heterogeneity. Over the past 50 years of development, the geologic study of this reservoir has relied on a large amount of well-log data in the field. However, a detailed reservoir description based only on wireline-log data cannot meet the requirements of oil field development. There is still some uncertainty about the sand boundary and geometry, due to reliance only on data from fields with an average density of approximately 100 wells/km~2. Such uncertainty may severely affect the potential for producing the remaining oil in these mature oil fields. In this study, seismic-sedimentology guided reservoir prediction is examined in an area of dense wells in BB2 block in the Changyuan LMD oil field. The spatial distribution of channel-sand bodies was identified and recognized by facies analysis, sandstone thickness mapping, and seismic stratal slicing of reservoir units, using the principles and methods of seismic sedimentology. The results showed that the seismic amplitude can be correlated to log lithologies. The interpretation of sandstone can be improved by 90°-phase seismic data, and the distribution of channel sand with a thickness greater than 5 m can be directly predicted. The identification and prediction of the boundaries of channel-sand bodies are thus improved. The results have proved useful in new infill drilling and reperforations.