转向压裂增产评价方法

转向压裂是一项新兴的水力压裂技术，在平面渗透率各向异性储层中转向垂直裂缝具有更好的增产效果.基于渗流力学之汇源叠加理论，建立了平面渗透率各向异性储层中转向垂直裂缝的增产评价解析模型，并给出了计算对比和应用算例.分析结果表明:裂缝与渗透率主轴间的夹角（裂缝斜角）微弱影响均匀各向同性储层中井的产能，但明显影响均匀各向异性储层中井的产能；裂缝斜角变化导致沿优势渗透率方向有效流入面积变化，有效流入面积越大，无量纲生产指数越大，产能亦高.因此建议选择平面方向渗透率差异较大的储层进行转向压裂，以期获得更好的经济效益. 

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.