Numerical Simulation of the Characteristics of Mud Invasion and Residual Oil Distribution in Low Permeability Reservoir

The original distribution of formation fluid around the well will be changed while mud filtrate invades permeability formations. Based on the water-oil phase flow theory and convective diffusion theory, the method ofnumerical simulation is applied to build the formation model for the study of the characteristics of mud invasion in low permeability reservoir, researching the distribution characteristics of salinity, water saturation, resistivity and remaining oil around the well during mud invasion. The numerical simulation results of mud invasion in different permeability formation show that mud invasion depth increases as permeability increases in the same invasion time in low permeability reservoir, and the invasion profile of salinity , water saturation ,resistivity and remaining oil change obviously as invasion time increases. Combined with practical well numerical simulation analysis found that the characteristics and resistivity separation of array induction logging response influenced by mud invasion depth and invasion time.The simulated results show that the distribution of remaining oil have obvious relationship with reservoir fluid property. Correctly understanding the characteristics of mud invasion and the distribution of remaining oil around the well can improve the accuracy in electric logging reservoir evaluation.