盐岩非线性流变性态及地下复杂溶腔变形数值分析

发布时间：2018-08-05 17:44

【摘要】：针对平顶山盐田盐岩层数多、单层厚度薄、泥岩夹层多的特点,建立等效复合单元代替互层状盐岩体,利用ABAQUS软件对马庄井田的地下溶腔进行三维数值模拟研究,探讨不同内压下,腔周塑性区围岩的非线性流变性态以及溶腔体积缩减规律。结果表明:(1)等效复合单元在稳态蠕变阶段具有较好的数值稳定性,泥岩能有效地限制黏塑性区范围以及围岩向洞内位移的发展;(2)在围压(8 MPa)作用下,互层状盐岩单元体基本呈现线性小变形特征,溶腔体积收缩率与蠕变持续时间均呈现最低值,分别为3%与2.5 a,随着内压增大(8~12 MPa),互层状盐岩单元体开始呈现非线性蠕变,但经过较短时间后(2.5 a)体积收缩率逐渐稳定至一较小值,约为3.5%,随着内压的迅速减小(≤4 MPa),腔周盐岩逐渐呈现非线性大变形特征,表现为稳态蠕变时间增长,蠕变速率增加,5 a后围岩蠕变仍在稳定增加;(3)塑性区围岩内的黏滞系数随时间普遍加大,体现了互层状盐岩在储气运行过程中越来越稳定的变形趋势,因此,实际运行时储气压力应控制在合理范围(4~12 MPa),尤其要减少在较小内压下的蓄气运行时间。
[Abstract]:In view of the large number of salt rock layers in Pingdingshan salt field, the single layer thickness is thin and the mudstone interlayer is many, the equivalent composite element is established to replace the interbedded salt rock. The three-dimensional numerical simulation of the underground cavity in the Ma Zhuang coalfield is studied by ABAQUS software. The nonlinear rheological behavior of surrounding rock in the surrounding plastic zone and the volume reduction of the cavity are discussed under different internal pressure. The results show that: (1) the equivalent composite element has good numerical stability in the steady state of creep, and the mudstone can effectively limit the scope of the viscoplastic zone and the development of the displacement of the surrounding rock to the cave. (2) under the confining pressure (8 MPa), the interbedded salt rock unit has the characteristics of the linear small deformation, the volume contraction rate of the cavity and the duration of the creep. The minimum values are 3% and 2.5 A, respectively. With the increase of internal pressure (8~12 MPa), the interbedded salt rock unit begins to show nonlinear creep, but after a short time (2.5 A), the volume contraction rate is gradually stable to a small value, about 3.5%. With the rapid decrease of the internal pressure (less than 4 MPa), the surrounding rock salt rock gradually presents nonlinear large deformation characteristics. The steady creep time increases, the creep rate increases, and the creep of the surrounding rock increases steadily after 5 a. (3) the viscosity coefficient in the surrounding rock of the plastic zone increases with time, reflecting the more stable deformation trend of the interbedded salt rock in the process of gas storage operation. Therefore, the gas storage pressure should be controlled in a reasonable range (4~12 MPa), especially in the actual operation. It is necessary to reduce the operating time of the storage under the smaller internal pressure.
【作者单位】：郑州大学水利与环境学院;河南省煤田地质局资源环境调查中心;
【基金】：国家自然科学基金资助项目(41272339)
【分类号】：TE972.2

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