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盐穴地下油气储库在长期运行过程中的地表沉降预测是储库安全评价的重要内容,目前尚无成熟的基于力学理论的解析模型。将盐穴储库地表沉降问题近似为半无限空间内球型空洞受力收缩导致的边界位移问题,利用弹性无限域内球型空洞受力收缩的球对称位移解,运用叠加原理,推导得到半无限空间球型空洞在一定内压作用下引起的地表沉降的弹性积分形式解析解。然后运用对应原理,将体积变形视为弹性,畸变视为Maxwell黏弹性,对地表沉降弹性解析解进行拉普拉斯变换,得到时空域上的地表沉降的黏弹性积分形式解析解。通过与数值模拟结果的比对,验证了文中弹性模型的准确性。最后将沉降预测黏弹模型运用于某盐穴储库地表沉降的预测分析,并与该储库现场沉降观测数据进行对比,分析表明,新模型能够很好地预测盐穴储库地表沉降及发展趋势,该模型为储库地表沉降预测提供了一套新的基于力学理论的方法。
Surface subsidence prediction of salina reservoir in long-term operation is an important part of reservoir safety evaluation. There is no mature analytical model based on mechanics theory. The problem of surface subsidence of salt cavern reservoir is approximated as the boundary displacement problem caused by the contraction of spherical cavity in semi-infinite space. By using the superposition principle, the semi-infinite Analytical Solution of Elastic Integral Form of Ground Subsidence Caused by a Certain Internal Pressure in Spatial Cavity. Then, using corresponding principle, volume deformation is considered as elasticity and distortion as Maxwell viscoelasticity. The Laplace transform is applied to the analytical solution of surface subsidence, and the viscoelastic integral form analytic solution of surface settlement in time-space is obtained. By comparing with the numerical simulation results, the accuracy of the elastic model is verified. Finally, the prediction and analysis of the surface subsidence of a salt cavern reservoir by using the predictive viscoelastic model is compared with that of the reservoir subsidence. The analysis shows that the new model can well predict the surface subsidence and development of salt cavern reservoirs This model provides a new set of mechanics-based methods for reservoir surface subsidence prediction.