Lithofacies Palaeogeography Of Badaowan Formation (Jurassic), Zhong2Block, Junggar Basin

Junggar Basin is a large oil and gas superimposed inland basin of China. Thestudy area, Zhong2block, is located in the northeastern part of the central JunggarBasin. Through the integrated analysis of the core, seismic and well log data, itshowed that tectonic and climatic conditions in the study area of the basin is mainlydue to the impact of sequence stratigraphy development. Based on identification ofseismic, well logs, core cross section as well as other coal strata signs, classificationof sequence boundaries, and the application of the theory of multi-level sub-stratacycles, We have establish an effective isochronous sequence stratigraphic framework.Sedimentary rocks in the study area are mainly fine sandstone, coarse sandstone,conglomerate and mudstone, showing lower physical structure maturity. Combinedwith coring wells lithology, provenance, sedimentary structures, and paleontologicalfeatures, it is feasible to determine the type of sedimentary facies corresponding tobraided fluvial fan deposits, including micro-facies types of bar, braided chanenl, andoverflow. Thin section, scanning electron microscopy and X-ray diffraction analysisshowed that the studied sandstones are extremely low porosity and ultra-lowpermeability reservoirs. Cementation and dissolution are the main diagenetic features.In addition, the diagenetic stage corresponds to early B diagenetic stage to meso Adiagenetic stage. Besides, reservoir pore type is of secondary origin. Thus, lithofaciespalaeogeography study can be realized in the Zhong2block of central Junggar Basinfrom multiple perspectives.