Application Of Time-frequency Electromagnetic Method In Shazhang Fault Fold Belt Of Junggar Basin

Junggar Basin in Xinjiang is the second largest basin in China.Its well-developed reservoir and caprock make the area rich in oil and gas resources.In recent years,Carboniferous source rocks have been drilled in Jimusar depression and Gucheng depression respectively,which confirms the great potential of Carboniferous as effective source rocks in Zhundong area.The shazhang fault fold belt in the study area is the second-class structural unit in the karamaili Piedmont depression in the northeast margin of Junggar basin.The existing data have basically defined the fault distribution characteristics and basic structural units in the eastern uplift area.However,due to the complex petroleum geological characteristics of the shazhang fault fold belt,the Carboniferous system is deeply buried,especially the understanding of lithology,reservoir development and reservoir forming law still exists insufficient,It is difficult to describe the residual sedimentary structure of Carboniferous,which seriously restricts the exploration process in this area.Therefore,it is great significance to change the previous exploration mode and use the new method for oil and gas exploration in shazhang fault fold belt.Time-frequency electromagnetic method is a new geophysical exploration technology developed in recent years for the exploration of oil and gas reservoirs.Its exploration efficiency,detection depth and resolution are significantly improved compared with the previous electromagnetic method.This technology can obtain the electric and magnetic field responses in time domain and frequency domain,and then extract the resistivity and induced polarization information from them,which can further divide the stratum structure and predict the favorable area of oil and gas.In this paper,the time-frequency electromagnetic method is used as the exploration method.Five survey lines with a total length of 195 km and a total of 980 physical points are deployed in the study area.Through time-frequency electromagnetic data acquisition,processing and interpretation,the limitations of previous seismic data imaging are overcome.The forward simulation is used to determine the most reasonable construction parameters of time-frequency electromagnetic,so as to ensure that the interference of time-frequency electromagnetic signal strength,resolution and exploration depth is small.The data collected in the field is processed and calculated,the physical parameters are qualitatively analyzed,and then the resistivity and polarizability are quantitatively constrained and inversed to solve the distribution of resistivity and polarizability at different depths,forming corresponding depth profile,through the IPR comprehensive abnormal analysis,combined with the previous geological and geophysical results obtained by seismic and drilling methods in this area,the favorable area for oil and gas in shazhang fault fold belt area are comprehensively evaluated,implement the distribution law of oil and gas reservoirs in this area,the favorable exploration direction of Carboniferous system is determined,and the favorable area for oil and gas are proposed for the next oil and gas exploration decision and objective evaluation and optimization provide the basis.