A Saturation Interpretation Model for Low Porosity and Permeability Reservoirs Based on the Pore Geometric Conduction Theory

Due to the effect of complex pore structures in low porosity and permeability reservoirs,it is necessary to build a saturation model that can give a better description of effects of the pore structures on conductance characteristics of the rocks in low porosity and permeability reservoirs.Pore geometric conduction theory,proposed by Herrick and Kennedy,is suitable for interpreting effects of the pore structures on the conductance rules of the rocks.In the theory,several variables are introduced to reflect influence of pore geometry and geometrical distribution of formation water on conductivity of the rocks.Based on pore geometric conduction theory and characteristics of pore structures in low porosity and permeability reservoirs,a general saturation interpretation model for low porosity and permeability reservoirs is established in this paper.In the model,conductivity of the rocks is considered to be the sum of equivalent conductivity of clay bound water,microscopic capillary pore water and free water,and the effects of clay bound water pore geometry,microscopic capillary pore geometry,free fluid pore geometry and geometrical distribution of free water on rock conductivity are also considered.The precision of the model is verified,and the determination of the parameters in the model is also given with core experimental data in F formation of Daqing C area.Then,some log data are processed with the model and parameters,and the results are compared with core analysis water saturation in sealed coring well and well test results.The results show that the new saturation equation can be applied in saturation evaluation of low porosity and permeability reservoirs.