| In this paper,168 blocks of natural core in late stage of super high water cut in almond oil field are selected.Through conventional mercury pressure test,scanning electron microscope experiment,casting thin film experiment and X diffraction experiment,the difference of pore structure between high permeability layer and oil thin oil layer is given,and three intervals of thin oil layer are divided,further through fractal theory and CT scanning experiment A deep study of thin and poor oil layers.The results show that with the increase of permeability,pore radius increases,the displacement pressure is low,and pore throat separation is good.The thin difference oil layer is divided into three intervals through the pore distribution peak parameters: the interval I is a thin difference layer with the permeability at 131×10-3?m2-270 ×10-3?m2,the pore distribution peak is 6.3?m,the positive correlation of the pore distribution peak and permeability is similar to the high permeability layer,and the pore distribution peak value is not superimposed,and the interval II is permeation.The rate is in the thin difference layer of 71.4×10-3?m2-131×10-3?m2.The range of permeability contains two pore distribution peaks,which are 6.3?m and 4?m respectively,and the interval III is the superposition of three pore distribution peaks in the permeability range of 53×10-3?m2-71.4×10-3?m2,respectively,including three pore distribution peaks,respectively,and 4?m,respectively.2.5?m.Through the analysis of the three intervals of the thin oil layer by the mercury pressure test,the pore separation from the interval I to the interval III gradually becomes worse,the pore radius gradually becomes smaller and the reservoir property becomes worse.The pore throat distribution is uneven,the percolation capacity decreases,and the pore structure becomes more complex.The X ray diffraction technique is used to analyze the average pore radius and porosity from the clay content angle of the rock.From the interval I to the interval III of the thin oil layer,with the increase of clay content,the porosity and the average pore radius decrease,the permeability of the rock decreases and the reservoir physical property will become worse,which is the interval of the thin oil layer.The main reason for the superposition of pore distribution peaks is in II and interval III.With the gradual increase of fractal dimension,the corresponding relative separation coefficient and distortion also increase.The seepage channel of the interval I to the interval III in the thin oil layer is smaller,and the more rough the pore roar channel is.The pore throat ratio of high permeability core is small,and the distribution frequency is dispersed.The pore throat ratio of thin and poor reservoir is large and its distribution is concentrated.It can be seen that the pore throat ratio of thin and poor oil reservoir interval III is more obvious than that of permeability.When the permeability decreases,the ratio of pore throat ratio increases considerably. |
PDF Full Text Request