Reservoir architecture and remaining oil distribution in mouth bar-A case study on the braided delta of long-axis gentle slope in Zaonan fault block of Dagang Oilfield

Abstract

Cores, well logging and seismic and laboratory analysis data as well as hierarchical analysis, model fitting and numerical simulation methods, were used in the study of internal configuration and distribution of remaining oil controlled by intercalations in the mouth bar of Dagang Oilfield. Result shows that there are two intercalation distribution patterns in the mouth bar as the result of different unloading patterns of sediments in distributed channels, namely the lateral overlapping pattern and the upwarping pattern. The former presents itself as a lateral stack of intercalations with certain dips crossing source direction and the latter shows a parallel uplifting pattern of multiple intercalations crossing source direction. The scales and directions of different patterns vary greatly. Remaining oil distributions in intercalations of different patterns are different. Along the provenance direction, the oil gathered inside and at the front of prograding accretion formed within intercalations. When crossing the provenance direction, the oil accumulated in the lateral accretion bodies blocked by internal interlayers in the bar for the lateral overlapping pattern and in higher places for the upwarping pattern.