关键词: 水流优势通道, 储层非均质性, 剩余油, 点砂坝, 扶余油层

Abstract:

A point-bar reservoir readily forms dominant flow channels after long-term waterflooding development, resulting in a decrease of the waterflooding sweep efficiency and substantially affecting the distribution of remaining oils. Taking the S17-19 Block of the Fuyu Oilfield as an example, we studied the distributional pattern of dominant flow channels within point bars and its control on the distribution of remaining oils. Data of core analyses indicate that the water cut of dominant flow channels within point bars is greater than 95% and the corresponding oil displacement efficiency is greater than 35%. Reservoirs with either high heterogeneity or homogeneity and permeability greater than 80 mD are more easily to form dominant flow channels. Under the current well-pattern condition, dominant flow channels, with an average thickness of 2.2 m and width between 2 m and 4 m, commonly occur in the middle and lower parts of point bars. Controlled by main flow lines between injection and production wells, relatively high-permeability zones and high-permeability intervals in the lower part of point bars, dominant flow channels have built a complex network in space. Waterflooding is more serious in dominant flow channels than in non-dominant flow channels, but the latter is rich in remaining oils. Therefore, measures, such as rebuilding well-patterns, drilling horizontal wells, carrying out profile control and water plugging, adjusting development ways and implementing cyclic waterflooding, can break the current network of dominant flow channels and expand volumes of the waterflooding sweep efficiency to improve the displacement efficiency of point-bar reservoirs.

Key words: dominant flow channel; , reservoir heterogeneity; , remaining oil; , point bar; , Fuyu oil layer