Abstract: The study and practice show that permeability as a kind of vector is closely related to orientations for its scale. The origin of perme-ability vector is presented. Some confusable understandings that occur for application of the vector feature are analyzed. It is pointed out that the permeability means one within flow path, hence it couldn't exist independently without the flow path. Also, it has distinct physical meaning, the. artificial addition and decomposition of it like free vectors in mathematics can not made. Study indicates that two different directions of perme-abilty vectors could not serve as the permeability of corresponding direction for its resulting vector,nor the projection of a permeability vector on a direction as the permeability value on the projected direction. Also, a quantitative calculation model is deduced for anisotropic permeabili-ty, by which the horizontal permeability in any direction could be estimated. The model can be used for the conductivity estimation in different directions in reservoir simulation and for the well space design in different orientat ions in anisotropic reservoirs.

Key words: permeability, vector property, anisotropy, percolation