Research Of Sedimentary Facies Evolution Of Jurassic In Wuerhe-xiazijie Area In The Northwestern Edge Of Junggar Basin

Jurassic is one of the main oil and gas exploration strata in the Junggar Basin, the exploration acreage of Wuerhe-Xiazijie is 2000 km2. Predecessors have carried out some research including geological, stratigraphic and sedimentary facies, but the studies in reservoir rock characteristics and sedimentary characteristics are not systematic, detailed study of sedimentary microfacies dabble less. Based on previous studies, this article integrated using seismic, drilling, logging and laboratory analysis to research the stratigraphic division, source direction, sedimentary characteristics, vertical and horizontal distribution of sedimentary facies,and achieved results and understanding as below:①Comprehensive studied the sandstone composition, compositional maturity,heavy minerals,formation thickness,percentage of glutenite other characteristies, the target formation’s provenance in the study area was analyzed, the results show the provenance has a good inheritance in each group, there are two main directions of provenance: one is Zaire Hill in the south-west, the other is the Interchange of Zaire Hill and Sahara Alat Hill in the north-west.②Though analyzing the lithology, sedimentary structure, particle size characteristics and electrical characteristics in the study area, this article has Identified the sedimentary facies marks and made a single well sedimentary facies.③Combined with analysis of single well faeiesand profile correlation,depositional system of the target formation was shock fan- braided river- braided river delta. Badaowan, Xishanyao, Toutunhe have mainly developed braided channel facies, floodplain facies and braided river delta plain. Sangonghe and Qigu have mainly developed braided channel facies, floodplain facies.④In the background of the basin evolution, sedimentary Jurassic study area longitudinal plane profileand sedimentary layers of the phase diagram, analysis of Jurassic sedimentary facies evolution: Badaowan formation sedimentary period, the basin of braided river and braided river delta sedimentarycharacteristics, humid climate, the formation of coarse clastic sedimentary coal bearing. Sangonghe formation sedimentary period, due to the northwestern margin of the Zaire mountain uplift effectlayer, the study area mainly developed braided river facies, sedimentary period, the basin experienced large-scale invasion of lake, the center of the sag delta facies, Zaire mountain sourceformation of braided river delta sedimentary enormous. Xishanyao formation sedimentary period, the western basin uplift resulted in deposition ofdeletion, near the Zaire mountain side of braided river is widely distributed, the lake area only distributed in the depression center; research areas of the Piedmont depression center transition tostill rely on Zaire mountain source formation of braided river delta sedimentary huge, the climate was warm and wet the formation of flooding, large-area marsh, swamp, Binhu river swamp environment, become the heyday of coal seam. Toutunhe formation sedimentary period, piedmont is characterized by the deposition of braided river, the center of the sag basingradually narrowed, research on large area deposition of delta plain. Qigu formation sedimentary period, the tectonic activity is more active, fast denudation,rapid deposition formation, lithology with red(dark red) deposition, dry climate; the braided riverfacies feature, formation were denuded, seismic profile display for the truncated contact relationship.