考虑裂缝变形的地下储气库数值模拟研究

NUMERICAL SIMULATION RESEARCH ON UNDERGROUND GAS STORAGE CONSIDERING FRACTURE DEFORMATION

在Warren-Root双孔模型的基础上,考虑了枯竭裂缝性油藏型储气库运行过程中,压力反复升降使介质发生不完全可逆变形对储气库孔隙度和渗透率的影响,建立考虑介质变形的枯竭裂缝性油藏型地下储气库的数学模型,应用该模型进行了实例计算。算例分析表明:随储气库运行时间的增加,考虑变形的储气库压力和注气井井底流压逐渐升高、孔隙度和渗透率逐渐降低;而未考虑变形的储气库压力在一定范围内波动,注气末井底流压基本保持不变;在模拟储气库运行4年后,考虑变形计算的储气库压力比未考虑变形储气库压力高1.2MPa,注气井井底流压高2.96MPa,孔隙度是原始孔隙度的0.96,渗透率是原始渗透率的0.87,由此可见裂缝性油气藏型地下储气库的地层变形不能忽略,建议在天然气地下储气库矿场应用和理论研究时考虑裂缝变形对储气库的影响。

The influence of rock deformation on reservoir porosity and permeability is taken into consideration in this paper.Based on Warren-Root dual-porosity model,the mathematical model of gas storage that accountes for fracture deformation's influence is developed.A real case is calculated with the model.The result analysis shows that with the increase of the total operation time,gas storage pressure and gas injection well bottom hole pressure increases,porosity and permeability decrease.The gas storage pressure without deformation effect fluctuates in a certain range,and the bottomhole pressure of gas injection well without deformation effect basically remains the same.At the end of the 4th year within simulating time,gas storage pressure with deformation effect is 1.2 MPa higher than that without deformation effect,gas injection well bottomhole pressure is 2.96 MPa higher.While the porosity is 0.96 times of original value,and permeability is 0.87 times of original permeability,which indicates that the fracture deformation effect cannot be neglected in the study of depleted fractured reservoir underground gas storage.It is suggested that deformation effect should be take into account in field application and theoretical investigation of underground natural gas storage.