摘要
非常规储层水力压裂过程中套管剪切变形问题突出，现场缺乏合适的套管变形防控措施。基于对套管剪切变形特征的分析，提出了通过合理设置避射距离防止套管变形的思路，并建立了套管剪切变形防控模型，对最优避射距离进行了优化，分析了射孔参数、泵注参数、地层参数等对最优避射距离的影响。结果表明：1）对于较小尺度的天然断裂，可以通过降低储层改造强度，减小其滑移量；对于较大尺度的天然断裂，需要避免其在水力压裂过程中被激活，活化风险可以利用避射距离进行表征。2）通过压裂参数优化，能够提高储层改造效果并控制套管剪切变形，随簇数及簇间距增加，最优避射距离总体减小；天然裂缝间距越小、长度越大，与井筒夹角越小，最优避射距离越大。3）昭通YS区块长度大于50 m的天然断裂为高风险断裂，建议设置41～82 m的安全避射距离。
Abstract
The casing shear deformation problem is serious in the process of hydraulic fracturing in unconventional reservoirs, and appropriate casing deformation prevention and control measures are lacking. Based on the analysis of the characteristics of casing shear deformation, the view of preventing casing deformation by setting the avoidance perforation distance reasonably is put forward. The casing shear deformation prevention and control model was established to optimize the avoidance perforation distance, and the influence of perforating parameters, pumping parameters and formation parameters on the optimal avoidance perforation distance was investigated. The results show that: (1) as for small-scale natural fault-fractures, the formation slip distance can be reduced by decreasing the reservoir reconstruction strength, and as for large-scale natural fault-fractures, the activation risk of natural fault-fracture can be characterized by the avoidance perforation distance to avoid activated in the process of hydraulic fracturing; (2) the fracturing parameters can be optimized to improve the reservoir stimulation effect and control the casing shear deformation. With the increase of cluster number and cluster spacing, the optimal avoidance perforation distance integrally decreases. The smaller the spacing of natural fractures, the longer the length, and the smaller the angle between the wellbore, the greater the optimal avoidance perforation distance; (3) the natural fault-fracture larger than 50 m in YS block of Zhaotong is easy to shear casing, and a safe avoidance distance of 41￣82 m is recommended.
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