Research On Microscopic Characteristics And The Relationship Between Microscopic Characteristics And Macro Indicators Of Low Permeability Reservoir

China has abundant resources of low permeability, which accounts for 54% of the total remaining resource.Therefore, how developing it efficiently has important strategical significance. But because the micro-pore structure of low permeability reservoir is complex, In the development process it shows the characteristic of low permeability, low pressure and low-abundance, which essentially affect the increasing of recovery. There is essential relationship between the macro development features and pore structure, so studying the pore structure is an effective method to explain the macroscopic development laws of low permeability.In this paper, by the combination of metallurgical microscope and depth of field expansion software, we developed a method of core micro-anatomy experiment which suited to observing the micro-pore structure of low permeability reservoir. This method enabled the observation of the core of natural cross-section, we used this method comparative studied the distribution of micro-parameters of Changqing oilfield and Daqing oilfield low permeability core, catched the main micro differences between low permeability core of these two fields. Comparing the cores in Daqing oilfield with that in Changqing oilfield, the tortuosity was lager and the shape-dependent constant was smaller and the pore shape was more complex. Taking of natural cores with different permeability levels from Daqing Oilfield, we processed them with scanning electron microscope, at last we obtained the characteristics of pore throat pictures which can be observed clearly under different magnifications. Through statistical analysis of particles, pores, throat and other parameters, we can analyze their distribution and relationship between permeability. We got that throat radius is the main decisive parameters of permeability. We in-depth studied the the relationship between micro-pore characteristics and the water flooding recovery in the way of combining indoor flooding experiments. The experimental results show that the pore throat ratio, shape factor have the greatest impaction on water flooding recovery,they are the main micro elements of low water flooding recovery.This paper studied the relationship between micro pore characteristics and macro development indicators of the low permeability reservoir. It has academic value and theoretical significance for correct, reasonable and efficient developing and transforming low-permeability reservoir.