Analysis of reservoir main controlling factors in the eastern margin of Ordos Basin:Taking Shihezi Formation reservoir as an example
To clarify the sedimentary facies characteristics and main controlling factors of reservoirs in the Shanxi Formation and Lower Shihezi Formation reservoirs in the Daning and Jixian areas of the eastern margin of the Ordos Basin,the delta front sedimentary facies type in the study area was defined based on logging data and seismic facies,and three kinds of sedimentary microfacies were subdivided into underwater distributary channel,estuary bar and underwater distributary channel.On the basis of clarifying the sedimentary facies characteristics of reservoir,the rock types were analyzed.Through the whole-rock diffraction data,it was found that the cementation of authigenic clay minerals or complex bases has a filling effect on the pores,which is the main reason affecting the reduction of pores in the study area.When the content of interstitial material is small,the corresponding reservoir permeability is good.The grain size of rock is obviously controlled by regional sedimentary evolution,and the quartz content of mineral composition is proportional to the physical property of reservoir,which is also one of the main controlling factors of reservoir.Through the observation of the core and the micro-scopic slice,it was found that the intergranular and intragranular dissolved pores in the pore type correspond to high quality reservoirs with high maturity.The maximum likelihood method was used to predict the plane development area of microfractures,which was con-sistent with the geological sweet spot area,revealing that microfracture development is one of the main controlling factors for the forma-tion of geological sweet spots and the accumulation of reserves.
eastern margin of Ordos Basinsedimentary faciesrock typespore typesmicrofracturescontrolling factors
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