通过大量文献调研指出,由于气体产出、低渗气藏孔隙压力降低、地应力增大、基岩和孔隙受到压缩,导致渗透率大幅降低和气藏产能降低。基于岩石渗透率随有效应力变化呈指数关系的普遍认识,在达西渗流理论的基础上,推导出了一个考虑渗透率应力敏感的气井稳态产能公式,并对其进行了实例计算分析,认为低渗气藏在产能预测时有必要考虑渗透率应力敏感伤害,特别是针对那些应力敏感伤害严重的低渗气藏;所推导的公式可为确定合理的生产压差和开采速度提供必要的理论基础。

Pore pressure decreases, effective stress increases, and permeability declines due to matrix and pore compression as gas produces in low-permeability gas reservoirs. This affects the deliverability of low-permeability gas reservoirs. Based on Darcy flow law and the universal cognition that the rock permeability varies with the effective stress exponentially, this paper presents a new equation considering rock permeability stress-sensitivity for estimating the productivity in low-permeability gas reservoirs. A case calculation with this new equation shows that considering permeability stress-sensitivity in the prediction is necessary, especially for the high stress-sensitive low-permeability gas reservoirs,and this will provide necessary reference to determining reasonable producing pressure drop and producing rate.