Drilling Fluid Leakage Model Based on the Dual-Medium Theory

In view of the lost circulation in carbonate formation, based on the dual-medium model, a two-dimensional transient model for fracture-porous formation is established. All the factors that influence the leakoff rate in the fracture-porous formation are analyzed. The result shows that the leakoff rate increases as the normal stiffness of the crack decreases; the leakoff rate increases as the initial fracture aperture increases; The larger the pressure difference is, the larger the drilling fluid leakage is; The larger the porosity is, the more drilling fluid flows from fracture to matrix, the slower the leakoff descent is; The larger the permeability of matrix is, the larger of leakoff rate is at the initial stage of leakage.