Research On Resistivity-Saturation Response Model Based On Pore Structure

Reservoirs with complex pore structures such as carbonate rocks,conglomerates and shale are currently the key exploration and development reservoirs in the oil and gas industry.Due to the many pore types and strong heterogeneity of pore distribution in this type of reservoir,there is still no effective method for pore structure description and water saturation estimation.It is of great theoretical and practical significance to establish the corresponding saturation inversion method based on the influence of formation resistivity.In this thesis,the spherical tube model is used to approximate the complex pore structure of the rock.Straight tubes of different sizes and shapes in three directions are used to approximate the resistivity anisotropy of the rock,and the series profiles within the response range of the logging tool are obtained by combining the renormalization method.For the equivalent resistivity of the block,two inversion methods,the half-division iteration and the Newton iteration,are used to predict the average saturation of the renormalized system with complex pore structure.As a focused resistivity logging method,trilateral logging has good stratification capability and radial detection depth,and is suitable for solving logging problems in high-resistivity thin layers.It is of great significance to the resistivity analysis of carbonate reservoirs with complex pore structure.In this thesis,the variational principle is used to form the final calculation format of the finite element method,and multiple observation data are obtained through effective forward modeling.This forward modeling process has good adaptability to both deep and shallow lateral logging.In this thesis,the Gauss-Newton constrained inversion method is combined with the tube model to obtain the saturation of the formation composed of different spherical tube models.The numerical simulation results show that the saturation inversion method in this thesis can divide the formation into finer elements,and the inversion accuracy is high,which provides method support for solving the pore structure parameters and saturation of complex pore structure reservoirs in lateral logging.