泥页岩水化膨胀的非线性蠕变模型

Nonlinear creep model of mud shale hydration expansion

泥页岩井壁岩石受到地下流体与入井流体的影响,具有明显的流变效应。根据泥页岩水化膨胀的流变力学行为,借鉴经典元件组合模型的建模思路,提出一种新的膨胀模型,将泥页岩水化膨胀蠕变过程的膨胀元件与黏性元件并联,结合非线性黏塑性体,能有效地模拟泥页岩水化膨胀的蠕变过程。该模型既能反映岩石水化膨胀后的衰减蠕变阶段和稳定蠕变阶段,又能反映岩石在高应力下的加速蠕变阶段的水化膨胀非线性蠕变过程。文中取长7泥页岩进行了蠕变试验,通过实验数据拟合发现,该模型可以很好地描述泥页岩水化膨胀后岩石的蠕变特性。

Mud shale sidewall rock under the influence of underground fluid and the fluid into the well has obvious rheological effect. Reference to classic element modeling ideas of combination model, according to the water absorption expansion of rheological mechanics behavior of the shale, this paper proposes a nonlinear hydration expansion rheological model, it has the expansion element with the viscous element in parallel, com- bined with nonlinear sticky plastic body, and can effectively simulate the swell of the shale creep process. This model can describe the rock after water absorption expansion of decay creep and steady creep, and to describe the accelerating creep of＇ rock under high stress. Based on model of long 7 mud shale creep test, data fitting results show that the model can well describe the mud shale hydration expansion after the creep properties of rock.