An in-depth analysis of reservoir architecture of underwater distributary channel sand bodies in a river dominated delta: A case study of T51 Block, Fuyu Oilfield, Jilin

Abstract

Guided by the concept of “model fitting, dynamic validation”, and based on the data of 10 coring wells, 257 logging wells, and the production performance in the dense spacing area during the past ten years, the underwater distributary channel sand reservoir in K1q4 of T51 Block, Fuyu Oilfield, Songliao Basin, was analyzed to examine the spatial distribution and identification marks of the architectures within the reservoir. Results indicated that the single channel sand body is 300–500 m wide and can be identified by such marks as inter-channel sediments, sand elevation difference between wells, difference of channel sand thickness, and “thick-thin-thick” sands association; the dip angle of the fourth-order interface is 0°–2°. Besides, the logging response characteristics and identification method of single channel sand bodies and their interior accreted bodies were defined for the reservoir. A 3D architecture model is established for the underwater distributary channel reservoir in the study area, providing a quantitative and reliable geological model for analysis of underwater distributary channel sands in the whole area. Key words: river dominated delta, Fuyu Oilfield, reservoir architecture, underwater distributary channel sand, barrier, interlayer