节理页岩水力压裂的数值仿真及试验研究-力学专业论文.docx

摘要页岩气开发的关键过程是页岩层的水力压裂，页岩气储层富含有机质，具 有较低的孔隙度和极低的基质渗透率。节理页岩微观结构的差异在宏观上表现 为力学性质的不均匀，对实际工程中节理页岩的水力压裂过程具有重要影响。 基于此，本文通过“RFPA-2D”以及“RFPA-3D”有限元软件，开展了节理页岩及石 膏模型的有限元数值仿真，选择石膏试样进行了相似性的试验研究，探讨了节 理页岩相关模型参数对其水力压裂过程的影响。本文在对现有岩石强度理论进行综述的基础上、以横观各向同性页岩为分 析模型，探讨了节理页岩的强度理论。利用“RFPA”二维、三维有限元分析软件 对节理页岩的水力压裂过程进行数值仿真，分析研究不同的页岩模型参数对节 理页岩水力压裂破坏过程的影响；进行了节理页岩的单轴压缩试验得出不同岩 样的弹性参数及力学性质曲线；并通过相似材料模型法，对石膏模型进行了水 力压裂过程的试验，研究发现试验结果与有限元数值仿真结果吻合较好。本文的有限元数值仿真结果表明，破裂压力随着节理倾角的提高而呈现出 先增后减的趋势，随着单轴抗压强度的提高而线性增大，而随着均质度的增大， 破裂压力前期提升较快，最终趋于平缓。有限元结果与试验结果均表明，孔隙 水压力场分布由孔洞形成环状向外径向扩散，微裂纹产生后逐渐开展并到达节 理面层，最终沿着节理面贯穿于整个岩体形成破坏面，说明了裂纹方向及破坏 面主要由节理面控制。关键词：节理页岩；水力压裂；数值仿真；破裂压力ABSTRACTThe hydraulic fracturing is the key process in the shale gas exploration. The shale gas reservoirs with low porosity and permeability is rich in organic matter. The difference of the Jointed shale micro-structure lead to its heterogeneous macroscopic properties which has great influence on engineering jointed shale hydraulic fracturing process. Based on it, this paper is desire to use RFPA-2D and RFPA-3D finite element software to carry out the finite element analysis of Joint shale and plaster samples, and has an analogous experimental research on the plaster samples for the sake of the exploration about the influence of the parameters of jointed shale samples in the hydraulic fracturing process.This paper discusses the existing theory of rock strength in a systematic way and has an analysis in the jointed shale samples which conclude the property of transversely isotropic. Based on it, the theory of jointed shale strength has been explored. With the help of the RFPA two-dimensional and three-dimensional finite element software, simulating the hydraulic fracturing process of jointed shale to research the influence in the hydraulic fracturing process with different parameters of jointed shale samples. The uniaxial compressive test of jointed shale gets a different kind of elastic parameters and the curve about mechanical properties. The similar mater