Abstract:

In order to recognize the internal structure of the alluvial fan reservoir and distribution of remaining oil and provide a more accurate geological basis for the well pattern adjustment and the remaining oil potentiality of production tail in oilfield, the Liuzhong area of Karamay  oilfield, as a case, is studied. Using the method of scale analysis and model fitting, the data of coring, outcrop, logging and performance, reservoir characteristics of alluvial fan in studied area is well researched. A comprehensive analysis method for reservoir architecture of alluvial fan is proposed. The result shows that the study area belongs to a part of the alluvial fan. The depositional model of alluvial fan was established. It can be divided into four zones, fanhead, intra middle fan, outer middle fan and fan margin-wetlands. The distribution of composite glutenite is divided into three patterns: a sheet distribution pattern in fanhead and intra middle fan, a broad ribbon distribution pattern in outer middle fan and a narrow ribbon distribution pattern in fan margin-wetlands. The overlying manners of a single conglomerate body are listed as five types, vertical-overlay, lateral-interleaving, lateral-overlying, lateral-separating, lateral-stitching.The quantitative scale of a single conglomerate body was established. The result of detailed architecture was verified by pressure coring well. Authors point out that the remaining oil is enriched near the sand body boundary.

Key words: Karamay oilfield, alluvial fan, reservoir architecture, depositional model, remaining oil distribution