储集层变形对低渗透凝析气藏衰竭相平衡的影响

在低渗透凝析气藏衰竭开采中 ,随着地层压力降低,储集层孔隙体积会随有效应力的增大而减小,针对此问题,在应力敏感实验的基础上,建立了考虑孔隙体积减小的凝析油气体系衰竭相平衡数学模型。实例分析发现,相对于定容衰竭过程,储集层变形使得其孔隙空间减小,孔隙中“较轻”的气体更多地被排出,地层流体相对“变重”,地层中的反凝析液饱和度增大。对应力敏感较强的储集层,应当考虑孔隙体积减小对凝析油气衰竭相平衡过程的影响。.

Impact of Reservoir Deformation on Phase Equilibrium in Depletion of Low Permeability Condensate Gas Pool

In the process of natural depletion of condensate gas reservoir, with decline of formation pressure and increase of effective stress, the pore volume of reservoir will decrease, allowing such a process to assume a declining process of the pore volume in physics rather than a process of constant volume depletion. For this reason, the mathematic model for phase equilibrium of condensate oil-gas system depletion, considering the pore volume decreasing is proposed on the basis of stress sensitivity test. The case study indicates that with respect to constant volume depletion process, the reservoir deformation will result in decrease of the pore space in it, and the lighter gas in the pore will be more discharged, forming "heavier fluid" and bigger retrograde condensed liquid saturation. So, for a reservoir with more intensive stress sensitivity, the influence of such a decline of pore volume on phase equilibrium process of condensate oil-gas depletion should be considered.