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众多已有盐穴地下储库群地面沉降监测数据和灾变实例表明盐穴储库群地面变形预测与控制是保证储库长期安全稳性运营的关键问题之一。中国盐岩地层盐层薄、成层分布的特点加剧了库区地表发生沉陷的灾变程度,直接影响到中国盐穴地下能源储备的安全。采用Gaussian曲线表示沉降分布,结合腔体收敛函数,建立了一套有别于概率积分法的地表变形预测理论—传递函数法。在此基础上,结合中国盐岩地层特点,对比计算了相同体积下椭球形、梨形与圆柱形溶腔在发生腔体完全收敛时所导致的地表最大变形量,并利用迭加原理对不同腔群分布形式、不同腔体间距下库区地表最大沉降进行了比较。研究认为,当单腔发生完全收敛时椭圆形腔体造成的地面沉降量最小,圆柱形最大;而库群对比计算结果表明腔体中心间距的增加将导致最优腔形的变化,并非椭圆形腔体始终最优。研究成果为中国油气储库建设中库区地表变形预测、腔体形状和布局优化以及相关规范的制定等方面提供了理论依据。
Many existing ground subsidence monitoring data and catastrophic examples of underground caverns show that the prediction and control of ground deformation of cavern reservoirs is one of the key issues to ensure the long-term safety and stability of the cavern. The salt strata in China’s salt strata are characterized by thin layers and stratification, which exacerbate the degree of catastrophic subsidence in the surface of the reservoir area and directly affect the safety of underground energy reserves in China’s salt caverns. The Gaussian curve is used to represent the settlement distribution. Combined with the cavity convergence function, a set of surface deformation prediction theory - transfer function method is established, which is different from the probability integral method. On this basis, combined with the characteristics of rock salt strata in China, the maximum deformation of the ellipsoidal, pear-shaped and cylindrical cavities under the same volume in the complete convergence of the cavity is calculated and compared with the principle of superposition The distribution of cavity groups and the maximum settlement of the surface of the reservoir under different cavity spacings are compared. The results show that when the single cavity is completely converged, the elliptical cavity causes the smallest amount of surface subsidence and the largest cylindrical shape. Comparing the results of the reservoir group shows that the increase of the cavity center spacing will lead to the change of the optimal cavity shape, The cavity is always optimal. The research results provide a theoretical basis for prediction of surface deformation, optimization of cavity shape and layout, and formulation of relevant norms in the construction of oil and gas reservoirs in China.