Sedimentary Characteristics And Favorable Facies Prediction Of The First Member Of The Jurassic Toutunhe Formation In The Fudong Slope Area Of The Junggar Basin

Through continuous drilling and research,it is found that the Toutunhe Formation in the Fudong slope belt is the main occurrence area of oil and gas reservoirs.Due to the huge amount of resources in the study area,the sedimentary characteristics of different regions are quite different,and the overall understanding is not carried out.The sedimentary causes of Fudong slope area are quite different,the scale and distribution of sand bodies are not clear,and the dominant facies are unknown,which restricts the subsequent rolling exploration process.Therefore,through the core,logging data and seismic data of the first member of Fudong slope area,the sedimentary characteristics analysis,particle size curve analysis,seismic attribute analysis,pore structure analysis,clay minerals and other conventional physical property analysis data are studied,which lays the foundation for clarifying the sedimentary favorable facies belt and predicting the favorable reservoir distribution in the study area,and provides geological basis.The research results and understandings obtained in this paper are as follows :(1)Based on the comprehensive study of the particle composition of rock clastic rock skeleton,the characteristics of heavy mineral assemblage,the contour map of heavy mineral,the contour map of heavy mineral peak shape and the ZTR contour map of heavy mineral in the target layer of the study area,combined with the previous structural research,combined with the regional structure,sedimentary background and outcrop investigation,it is finally determined that the provenance direction of the study area is from the northeast direction,mainly Qitai uplift and Beisantai uplift after denudation.(2)On the basis of fine description of the core of the first member of Toutunhe Formation in Jurassic of 13 coring wells in Fudong slope area,the color characteristics,rock characteristics and sedimentary structure of the core of the coring wells are identified and analyzed in detail.Through the statistics and analysis of the data of the analysis test,the probability cumulative curve is compiled,and the logging facies template,core facies template and seismic facies template in line with the first section of the study area are formulated.Finally,combined with the information of rock,electricity and earthquake,it is determined that the study area mainly develops shallow meandering river delta sedimentary facies,and its subfacies mainly develops meandering river delta front.The main channel,underwater distributary channel,mouth bar and sheet sand sedimentary microfacies are identified and subdivided in the first section of Toutunhe Formation in the study area.(3)Through the analysis of the sedimentary microfacies evolution of the vertical section of the core single well comprehensive histogram and single well microfacies comprehensive histogram in the study area,and then the analysis of the well-connected section in the study area combined with the analysis of the seismic geological interpretation section,the evolution process of the horizontal development and vertical development is accurately understood,and the sedimentary microfacies are finely characterized.The multi-parameter sedimentary facies map is used as the main line to clarify the sedimentary system and sedimentary facies distribution characteristics of the block,and the evolution law of the sedimentary distribution and the characteristics of the spatial distribution of the sand body.On this basis,the Jurassic sand bodies in the study area are accurately characterized by the maximum amplitude attribute of the target and the integrated interpretation technology of wave impedance inversion.Further,the plane facies distribution of the first member of the study area is determined by combining with the plane distribution map of sand content,and the plane facies maps of two stages of transition from meandering river delta to meandering river are depicted.Finally,the three-dimensional evolution and deposition model of the study area is established.(4)Through the comprehensive analysis of pore types,physical properties and occurrence state and characteristics under Yi / Meng mirror in the study area,it is shown that there are six types of reservoir space in the first member of Toutunhe Formation of Jurassic in Fudong Slope,including primary intergranular pore,microfracture(true fracture),dissolved intergranular pore,dissolved intergranular pore,residual intergranular pore and intragranular dissolved pore.Combined with the classification standard of CNPC reservoir,it is determined that the main reservoir of the target layer is medium porosity-medium low permeability reservoir.The grey theory is established based on the grey correlation method,and the porosity model is further established and verified.Finally,the favorable facies zone of the first member of Toutunhe Formation in the study area is delineated.According to the advantages and disadvantages,four grades are divided and scored,and the oil test suggestions of key wells in the well area are restored.Finally,a strong geological basis and technical support are provided for the rolling exploration and development of oil and gas and the recovery of oil test of old wells in the study area.