Genesis Mechanism of Low Resistance Oil Formation and New Method of Fluid Property Identification in the Guantao Formation,Bohai A Oilfield
As an unconventional,hidden and special oil formation,the low-resistance oil layer has great exploration potential.The formation of low-resistance oil formation in the study area is influenced by multiple factors,and the contrast of logging response characteristics in the oil-water layer becomes low,which makes logging interpretation difficult.Firstly,the formation mechanism of low-resistance oil formations was analyzed from both macroscopic and microscopic aspects.Secondly,by combining logging,gas logging hydrocarbon components and production and development data,and considering the characteristics of gas logging data in the study area,an improved method for calculating oil and hydrocarbon abundance was proposed to quantitatively identify low-resistance oil formations.The results show that the weak hydrodynamic environment and compaction are the macroscopic causes of the low-resistance reservoir,the high saturation of bound water due to the complex pore structure is one of the microscopic causes,and the difference of formation water mineralization due to the natural freshwater flooding formation mode is another microscopic cause.The improved hydrocarbon-bearing abundance can effectively and quantitatively identify the low resistance oil reservoirs in the study area,and can provide a quantitative basis for the tapping of low resistance oil reservoirs in the Bohai A oil field.