Seismic Description Of The Permian Upper Wuerhe Formation Oil Reservoir In Block 581, Junggar Basin

Large oil and gas reservoirs have been found in Upper Wuerhe Formation of Zhongguai area in Junggar Basin and commercial hydrocarbon flow has been obtained in most drilling wells,but the controlling factors and distribution of the reservoirs need further analysis and implementation.Based on 3D seismic data of 581 well region,the main research object in this thesis is the first stage of Upper Wuerhe Formation.The structural feature of Upper Wuerhe Formation has been cleared by fine structure interpretation and Variable Velocity Mapping.It's a monoclinic uplifting from southeast to northwest.The characteristic of faults has been confirmed by coherence technique.In northwest area,faults are well-developed and the stata has certain deformation.But in southeast area,formation is flat and level.The tectonic evolution of connecting well section which connect major structural zones has been analyzed by layer flattening technique.The ancient landform characteristics of the main oil generation period and the period before the deposition of first stage in Upper Wuerhe Formation have been analyzed by impression method.Sensitive parameters of logging response analysis shows that the impedance value of sandstone is higher than mudstone.The statistical relationship of seismic amplitude and sandstone's thickness shows that the seismic amplitude value of thick sand layer is smaller than thin sand-shale interbed.Combining the results of impedance inversion and seismic amplitude attribute analysis,the sand body distribution of first stage in Upper Wuerhe Formation has been predicted.Using frequency attributes and fusion attributes,the oil and gas distribution has been studied.And the result is identical with most oil and gas wells.Comprehensive analysis shows that the main controlling factor to sand body distribution is the ancient landform characteristics before deposition,and sand body developes in its valleys,gentle slopes and plain areas.If faults developed and reservoirs were excellent in those arears,oil and gas would be abundant.Finally,the optimum and suboptimum regions have been predicted.And these regions provide a reliable foundation for well deployment at the reservoir evaluation and development stages.