Sedimentary Characteristics And Sand Body Istribution Of Chang8Oil-bearing Layer Of Yanchang Formation In Zhenyuan Area, Ordos Basin

Based on sedimentology and sequence stratigraphy and Petroleum Geology theoryas the Guide, and Chang8oil-bearing layer of Yanchang formation in Ordos basin inzhenyuan area studies, systematic study on the sedimentary facies and sequencestratigraphy and analysis of distribution characteristics of sandbodies and make afavorable prediction and evaluation of sand, for Chang8reservoir in Zhenyuan areaset further oil and gas exploration and development provide important geologicalrealizations.According to detailed observation of the drill cores and the Petrology, sedimentarytectonics, paleontology, logging sedimentary facies identification to an in-depth studyequal, deepened the understanding of the Triassic Chang8oil-bearing layer ofYanchang formation in Zhenyuan area is shallow braided River Delta sedimentarysystem and distributary channel of Delta plain and leading-edge understanding ofunderwater distributary channel micro-facies. Sedimentary micro-contrast betweenthe wells and the wells based on the detailed study of Chang81reservoir smallsedimentary facies and sandbody surface distribution of the characteristics, whichreveals different patterns of sedimentary facies and paleogeography in the study arealandscape.1. Chang81reservoir in Zhenyuan area main for a big of Lake invasion Lake backdeposition sequence, since South West to North East to can divided out shallow-waterDelta plain, and shallow-water Delta front and shallow-water Fore-delta3subfacieswith, further subdivision for main river channel (central bar), and distributary channel,and depressions between distributary, and Crevasse fan, and underwater distributarychannel, and bay between distributary, and underwater Crevasse fan, and estuary dam,and far sand dam and the Fore-delta mud, deposition microfacies.2. By layer sequence structure type and overlay style, can will Zhenyuan areaChang8reservoir divided for1a long-term, and2a medium-term (including4a Lakeinvasion or Lake back sequence, respectively corresponds to Chang81and the Chang82of2a reservoir), and6a short-term benchmark surface cycles layer sequence (corresponds to Chang811, and Chang812, and Chang813, and Chang821, and Chang822, and Chang823). Stratigraphic classification and correlation on the basis ofStratigraphic thickness of vertical variations in the study area, a flat distribution werestudied, for, lithofacies and palaeogeography evolution of sedimentary facies andreservoir characteristic study laid the Foundation.3. High resolution sequence analysis and isochronous correlation based on thecombination of sedimentary facies and sequence analysis, developedsequence-lithofacies and paleogeography map depicts a distributary channel sandbodyand in-plane distribution characteristics and spatio-temporal evolution, for Chang8reservoir in Zhenyuan area team provides an important basis for exploration anddevelopment of oil and gas.4. Beneficial primarily for shallow-water sedimentary microfacies of reservoirdevelopment of deltaic distributary channel of Delta plain submarine distributarychannels and shallow, and shallow-water Delta plain of the river improvementactivities, sand has a considerable thickness, relatively good physical properties alongthe River towards the characteristics of good continuity and connectivity.