Yang Qi, Li Bin, Shao Mingren, Zhang Hongjie
China United Coalbed Methane Corporation Limited, Beijing 100011, China.
ACS Omega. 2021 Oct 4;6(40):26231-26238. doi: 10.1021/acsomega.1c03233. eCollection 2021 Oct 12.
Gas production from each perforation cluster has an obvious difference along with the horizontal wellbore in shale gas reservoirs. Some special perforation clusters evenly do not produce any gas, which means that those perforation clusters are not fractured. In shale gas reservoirs, only when the shale gas section was fractured with equal volumes of fracturing fluids, gas can be produced evenly. In this study, a stress theory around the perforation tunnel considering the stress around the wellbore and an induced stress by leaking of the fluid and the tunnel is presented. The results show that (1) fractures will quickly be created at two of the three perforation clusters and then the fracture of the cluster initiates. (2) The rate through each cluster is different, and the fracture volume created will have a big difference. (3) The fracture distribution between three perforation clusters are different, thus shale gas production also will be different. The theory and the method presented in this paper, can be used for different reservoirs besides shale gas reservoirs, thus it can be applied and referred widely.
在页岩气藏中，沿水平井筒各射孔簇的产气情况存在明显差异。一些特殊的射孔簇甚至完全不产气，这意味着这些射孔簇未被压裂。在页岩气藏中，只有当页岩气层段用等量压裂液压裂时，气体才能均匀产出。本研究提出了一种考虑井筒周围应力以及流体和射孔隧道泄漏引起的诱导应力的射孔隧道周围应力理论。结果表明：（1）三个射孔簇中的两个将迅速产生裂缝，然后簇间裂缝开始形成。（2）通过每个簇的速率不同，产生的裂缝体积也会有很大差异。（3）三个射孔簇之间的裂缝分布不同，因此页岩气产量也会不同。本文提出的理论和方法，除页岩气藏外还可用于不同的油藏，因此具有广泛的应用和参考价值。
