页岩油气水平井压裂裂缝复杂性指数研究及应用展望

The Fracture Complexity Index of Horizontal Wells in Shale Oil and Gas Reservoirs

为了评价页岩水平井压裂效果,将适用于直井的裂缝复杂性指数概念拓展到页岩水平井分段压裂中,考虑缝宽的非平面扩展、缝高的垂向延伸、主缝长的充分扩展和分段压裂的缝间应力干扰因子等因素,研究了不同裂缝类型对应的裂缝复杂性指数范围。对如何提高裂缝复杂性指数,进行了实施控制方法上的系统探索。结果表明,要增加裂缝的复杂性指数,一是要有一定的有利地质条件,二是需要优化压裂施工参数及现场实施控制技术。研究结果在四川盆地周缘4口水平井进行了应用和验证,每口井分段压裂10～22段,共实施65段140簇压裂,单段最大加砂量126m3,最大用液量达4.6×104 m3。压裂后复杂裂缝出现的概率为40%左右,部分井增产效果明显。

Based on the concept of fracture complexity index for vertical wells, the new one has been put forward and utilized in horizontal welVs multi-stage fracturing. The reconstructed concept of fracture complexity index was stretched to consider such factors as non-plain propagation in width, vertical fracture growth, sufficient reach of fracture length, and interference factor caused by induced stress between multi- stage fractures. What＇s more, the range of the complexity index for different type of fractures was studied. Correspondingly,a systematic study was conducted focusing on how to maximize fracture complexity index in field multi-stage fracturing. The final result indicated that not only the favorable geology parameters but also optimized fracturing treatment parameters and filed control measures should be matched up maximize complexity index. Moreover, 4 horizontal wells located in Sichuan Basin were conducted pilot test and ob- tained successful result. There were totally 65 stages （2-3 cluster for each stage） were hydraulically frac- tured and 140 separate fractures were available. By post analysis, the complex fractures may account for a- bout 40~ around. And some of the post-fracturing result was as well as expected.