Abstract: Existing researches of anisotropic oil reservoir mainly focus on two special types of well patterns in which the injectorto-producer or producer-to-producer direction is parallel to the principal permeability direction, and the studies concentrating on other types of well patterns are rare. The primary reason is that other types of well patterns might increase the uncertainty of development effect. Based on coordinate transformation method, the real anisotropic oil reservoir can be converted into a equivalent isotropic oil reservoir, and the flow field and development indexes of well pattern can be also calculated, and on this basis, the impact of the degree and direction of anisotropy on the development effect can be analyzed. Research results indicate that the existence of directional permeability can lead to deformation, even destruction and reconstruction, of original well pattern flooding units, when the principal permeability direction is neither parallel nor perpendicular to the injector-producer direction and injector-injector direction. The destruction and reconstruction of well patterns is a consequence of the anisotropic degree and the relative angel between anisotropic direction and well line direction, thereby resulting in the uncertainty of well patterns development effect. In anisotropic reservoir, the degree of anisotropy is greater, the deformation effect of well patterns is severer, and the development effect of well pattern is more sensitive to the change of angle between maximum principal permeability direction and well line direction. To avoid the occurrence of destruction and reconstruction effectively, the best choice for pattern configuration is making sure that the injector-to-producer or producer-to-producer direction is parallel to the principal permeability direction.

Key words: permeability, anisotropy, five-spot well network, destruction and reconstruction, streamline