Reservoir Structure and Remaining Oil Distribution of Meandering River Channels: A Case Study of the Y92-1 Layer in the Jingbian Oilfield, Ordos Basin

Abstract

The majority of the Jurassic Yan’an Formation reservoirs in the Jingbian Oilfield of the Ordos Basin have entered the middle and late stages of development, and fine characterization of reservoir heterogeneity and recognition of the remaining oil distribution are the keys to formulating comprehensive adjustment for production. The Y92-1 layer of the Yan’an Formation Y9 reservoir in the LZ area of Jingbian Oilfield is taken as the research object in this paper. Based on logging data, core, and other basic data, the reservoir morphology in the study area is finely characterized. Single-channel units are subdivided, and the reservoir configurations of different hierarchical levels are analyzed qualitatively and quantitatively. Finally, combined with the plane profile consistency analysis of the morphological characteristics of the sand body in layer Y92-1 and the injection production mode, it is concluded that there may be four distribution patterns of the remaining oil in the study area, and the composite river channel sand body dominated by the lateral superimposed mode under the inverse lateral accretion shale bed tendency injection condition is a favorable enrichment area for the remaining oil. This mode is mainly distributed in the boundary part of the different periods of single sand body superposition. These understandings not only deepen the significance of tapping the potential of the remaining oil in frequently rerouted meandering rivers but also could provide effective guidance for the further remaining oil tapping.

The pre-Jurassic Meng-Shaan paleochannel and its control on the accumulation model of Yan 10 reservoir in Central Ordos Basin

“…The sedimentary discontinuity surface of fine-grained sedimentation is the main marker of the vertical division of the thick channel sand bodies, and its electrical logging curves such as SP, RT mutation change, or return characteristics are more obvious and easier to identify as the thickness of fine-grained sedimentation becomes larger. Accordingly, by analyzing the characteristics of single-well logging curves and the longitudinal deposition pattern of the river 31 , through the cross-well profiles comparison method, the Meng-Shaan paleochannel overlay deposition was vertically divided into three periods of single-channel sand bodies, namely the Fuxian, Yan 10 2 and Yan 10 1 period (Fig. 7 ).…”