Chang8Reservoir Charateristics Study Of Triassic Yanchang Formation In West Ordos Basin

In this paper, the study has been carried on for about one and a half year since May2012.To achieve research purposes, a large number of test methods and much advanced analysis areused, such as ordinary slice analysis, cast thin sections analysis, scanning electron microscopy,energy spectrum analysis, X-ray fluorescence analysis, organic fluorescence analysis,cathodoluminescence analysis, mercury penetration analysis and oxygen carbon isotope, etc..These firsthand test data lay a solid foundation for completing this paper.Through systematic study, based on sedimentary types analysis of distributary channel,mouth bar and beach bar sand, sand body genetic model of Chang8reseroir in research area isestablished. Chang81resevoir sand body forms in depostional environment of relatively deepwater and abrupt slope, near to rich source, with sand body accumulation of continuousthick-layer retrogradation and continuous thick-layer aggradation. Chang82resevoir sand bodyforms in depostional environment of shore meare with insufficient source and repeatedlyelutriation by waves. From analysis of reservoir petrologic characteristics, lithology belongs tolithic feldspar sandstone and feldspar lithic sandstone, and grade is fine sandstone withrelatively fine-medium gradation. Diagenesis mechanism of different types is deeply explored,typical diagenetic evolution sequences of different areas are eatablished, and research area isascertained to be in A1~A2stage of mesozone rock as a whole. Lithogenous phase profile andplanar distribution diagram are drawn from point-line-face aspect, and single factorlithogenous phase planar distribution diagram of key diagenesis is simultaneously drawn. Sandbody physical characteristics of research areas are compared from the aspect of reservoir sandbody types. Physical characteristics of Chang81reseroir has the general tendency of overwaterdistributary channel> under water distributary channel> mouth bar> distal bar. Physicalcharacteristics of Chang82reseroir has the general tendency of overwater distributarychannel> beach bar. But physical property and general tendency of different reservoir sandbody in different systems have certain differences. Objective evaluation standar of Chang8reservoir of Yanchang formation in Ordos basin is established. By multi-map overlappingmethod, favorable reservoir distribution areas of Chang81and Chang82of the mainaccumulative sections in research area are predicted.