Enhancement Evaluation of Vertical Reorientation Fractures

Vertical reorientation fracture is a new hydraulic fracturing technique, which has been proved very effective in oil recovery enhancement, particularly in anisotropic reservoirs. In this paper, an analytical model has been derived to evaluate the productivity of the refractured wells drilled in anisotropic reservoirs by using sink-superposition theory, and computing comparison has been presented for illustration. It is concluded that the angle between the orientation of the secondary fracture and that of the dominant permeability has a little effect on the productivity rate when wells are drilled in isotropic formation, but it does have a strong impact on the productivity enhancement when wells are drilled in anisotropic formation; fracture orientation angles can influence the inflow area of fluid from the formation into the fracture along the dominant permeability direction; and the bigger the inflow area, the larger the dimensionless productivity index. Therefore, it is suggested wells drilled in formation with strong anisotropic properties should be preferred candidates for refracture treatment in order to obtain better economic benefits.