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根据我国油气储库多为层状盐岩的实际情况,基于流-固耦合分析理论,利用快速拉格朗日有限差分法对层状盐岩储库的渗流特性进行分析。研究了含夹层盐岩天然气储库流-固耦合效应,不同内压下的体积应变与围岩渗透率变化,围岩塑性区分布以及渗流量与渗透压力的变化规律。结果表明:渗透率与体积应变的关系可近似采用线性函数描述,体积应变增大时,盐岩内部空洞和裂隙扩大,使盐岩渗透率增大;在某个渗流压力(洞室内压)条件下,随着盐岩的流变变形,渗流量会趋于某一定值,渗流达到稳定状态。在天然气内压与围岩应力共同作用下,储库围岩塑性区扩展深度随着内压的增大而减小,研究结果对盐岩储气库的安全运行具有一定的指导作用。
According to the fact that most oil and gas reservoirs are stratiform salt rocks, the seepage characteristics of layered salt rock reservoirs are analyzed by fast Lagrange finite difference method based on the theory of fluid-solid coupling analysis. The fluid-solid coupling effect of gas reservoirs with intercalated salt rocks, the volume strain and wall rock permeability under different internal pressures, the plastic zone distribution of surrounding rock, and the variation of seepage and infiltration pressure are studied. The results show that the relationship between permeability and volumetric strain can be approximated by the linear function. When the volumetric strain increases, the cavities and fissures in the salt rock expand and the permeability of salt rock increases. Under a certain seepage pressure With the rheological deformation of salt rock, seepage flow will tend to a certain value, seepage to reach a steady state. Under the joint action of internal pressure of natural gas and surrounding rock stress, the expansion depth of plastic zone around reservoir decreases with the increase of internal pressure, and the result of the study can guide the safe operation of salt rock gas storage.