深部三场环境下页岩蠕变模型的建立与试验

 针对深部环境的复杂性，建立了温度-应力-化学三场共同作用下页岩试样蠕变模型，并探讨了其作用机制。研究表明：页岩在复杂环境下蠕变特性的温度效应和pH 值化学效应明显，同一级应力水平下温度越高或者化学酸碱性越强，页岩的瞬时应变、蠕变应变及蠕变速率越大，达到稳态蠕变阶段的时间也明显延长。pH 值对蠕变特性影响程度比温度的影响更明显。采用非线性元件代替常规线性元件，得到了页岩在深部环境下非线性黏弹塑性蠕变模型，该模型符合深部实际情况，能较好地模拟页岩在深部复杂环境下蠕变，从而求出模型参数。通过试验数据和拟合曲线吻合情况，验证了本模型的正确性。

Creep Model Establishment and Experimental Study of Shale Under Three Field Deep Environment

Due to the complexity of the deep environment, a creep model is built and the experimental study is conducted of the shale under the thermal-mechanical-chemical joint actions, and the corresponding mechanisms are investigated. The experimental study reveals that both the temperature and the chemical pH value play a promoting role in the process of creep under this complex environment, and the higher the temperature or the chemical pH value, the larger the instantaneous strain, the creep strain and the creep rate will be, and the longer it will take to reach the steady-state creep stage; the impact of the chemistry pH value on the creep properties of the shale is more significant than that of the temperature. With the method of replacing the conventional linear component with a nonlinear one to describe the nonlinear rheological part, a nonlinear viscoelasto-plastic creep model of the shale under the deep complex environment is built, which agrees well with the actual deep situation and can better simulate the creep properties under the deep complex environment. The model parameters are obtained, and the correctness of the model is verified by comparing the experimental curves with the theoretical ones. This model can be used for the shale creep behavior prediction at various temperatures and pH values within the range discussed in this paper.