A Novel Method for Stress Calculation Considering the Creep Behaviour of Shale Gas Reservoir
A Novel Method for Stress Calculation Considering the Creep Behaviour of Shale Gas Reservoir
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DOI：
10.25103/jestr.094.19
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发表时间：
2016-08
影响因子：
--
通讯作者：
Chongjia Yu;Haibo Li;Renjie Wu;Yuqi Sun
中科院分区：
文献类型：
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作者：
Chongjia Yu;Haibo Li;Renjie Wu;Yuqi Sun
为了研究气固热耦合条件下蠕变对应力场的影响，基于最小能耗原理，提出了一种考虑页岩气藏蠕变行为的应力计算方法。然后，采用室内试验和数学拟合的方法，分析了页岩的蠕变本构模型、页岩气的赋存状态、应力和温度。此外，还从理论上推导了渗透系数、孔隙度和体积应变之间的非线性关系。结果表明，所建立的蠕变损伤模型不仅可以描述蠕变的衰变阶段和稳定阶段，而且可以描述加速蠕变阶段。温度对岩体力学性质的影响符合多项式特征。随着温度的升高，弹性模数缓慢下降，粘滞系数迅速下降。温度对页岩气吸附的影响符合线性特征。朗缪尔体积和朗缪尔压力与温度成反比，前者减速快于后者。该方法可用于评价页岩气井的应力场。该研究为页岩气井的重复压裂和气体流动分析提供了新的途径。
To study the creep effect on the stress field under gas–solid thermal coupling, a novel method for stress calculation considering the creep behaviour of shale gas reservoir was proposed based on the principle of least energy consumption. Then, laboratory tests and mathematical fitting methods were adopted to analyze the creep constitutive model for shale, existence states of shale gas, stress, and temperature. In addition, the nonlinear relationship among permeability coefficient, porosity, and volumetric strain was theoretically derived. Results indicated that the established creep damage model can describe not only the decay and steady creep stages, but also the accelerating creep stage. The temperature effect on the mechanical properties of the rock mass conformed to polynomial characteristics. The elastic modulus slowly decreased and the viscosity coefficient rapidly decreased with increasing temperature. The temperature effect on shale gas adsorption conformed to linear characteristics. The Langmuir volume and Langmuir pressure were inversely proportional to temperature; the deceleration of the former was faster than that of the latter. The proposed method can be used to evaluate the stress field of shale gas wells. This research provides a novel approach for refracturing and analysis of gas flow in shale gas wells.