Application Of CEMP In Oil And Gas Exploration In Altay Area

Junggar Basin is a large petroliferous basin.Large oil and gas fields have been found in the northwest margin,southern margin and central part of the basin,while the degree of oil and gas exploration and development in Wulungu Depression in Altay area in the northeast margin of the basin is still low.The available data show that the Carboniferous strata in the Wulungu depression in Altay area have oil and gas exploration prospects,but due to the development of Carboniferous igneous rocks,the depth of burial,the complex tectonic-sedimentary background,and the shielding effect of the top igneous rocks,the Carboniferous seismic reflection signal-to-noise ratio is low,so the continuous electromagnetic profile(CEMP)exploration with Carboniferous as the main target layer is carried out in Wulungu Depression in Altay area.Through the analysis and interpretation of the data,the structures and structural traps in the study area are inferred,and the main stratigraphic interfaces and facies zones are divided,which provides an important basis for the evaluation of favorable areas for oil and gas exploration.On the basis of in-depth analysis of regional geological conditions and geophysical characteristics,the research work summarizes the characteristics of structural units,strata and faults in the area.Based on the basic principle of magnetotelluric sounding method,this paper uses numerical simulation method to forward deduce fault structural oil and gas model and basin type oil and gas reservoir model in order to understand the electromagnetic response characteristics of these two models.In the aspect of numerical inversion,the numerical simulation is used to analyze the difference between the inversion results of two typical magnetotelluric sounding data inversion algorithms of OCCAM and NLCG.The one-dimensional inversion results of OCCAM are used as the initial model of two-dimensional NLCG inversion and the inversion results are evaluated.It is found that the two inversion algorithms have complementary advantages,which provides a basis for the processing and interpretation of the measured data.This paper focuses on the field work layout and data collection of CEMP.Through polarization pattern recognition,denoising processing and static correction,the data are preprocessed,and the curve type analysis,total longitudinal conductivity analysis,apparent resistivity and impedance phase section analysis are completed,and the quantitative inversion calculation of the data is completed on the basis of qualitative analysis,and the resistivity profile of two-dimensional inversion is obtained.Comprehensive geological-geophysical data of the survey area for geological interpretation.The structural characteristics of the study area are clarified,the distribution characteristics of faults are further confirmed,the distribution characteristics of Carboniferous strata are identified,and the distribution characteristics of Carboniferous volcanic rocks in the deep prospect strata of the study area are identified.Combined with the borehole data in the adjacent area,it is inferred that the whole source-reservoir-cap assemblage and oil and gas-bearing conditions of the lower Carboniferous source reservoir,Upper Carboniferous and Mesozoic reservoir and Mesozoic caprock of the two structural units in Fuhai depression and Zhaheba depression are better.The trap structure has good oil and gas accumulation conditions and has a good prospect for oil and gas exploration.Through this work,the continuous electromagnetic profile method has achieved good results in oil and gas exploration in Wulungu depression,which has a certain reference value for the next step of oil and gas exploration and evaluation in this area.