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为准确量化正负效应对相渗曲线的影响,采用欠饱和物质平衡方程,将改进的PMG绝对渗透率模型与CPL相对渗透率模型在相同储层压力与含水饱和度下耦合,建立了考虑水侵的欠饱和煤储层有效渗透率动态预测模型,并分析了气水有效渗透率动态变化规律.研究表明:模型将有效渗透率统一为储层压力的函数,能很好反映煤储层正负效应,特别是基质收缩对于气相有效渗透率的改善作用;水侵引起净产水减少,导致含水饱和度降低变缓,抑制气相有效渗透率的升高与水相有效渗透率的下降,但对曲线形态影响微弱;若水侵量不再变化,定速水侵就转化为定量水侵.适当提高排水速度有助于降低水侵的影响.
In order to accurately quantify the effect of the positive and negative effects on the phase-infiltration curve, the unsaturated PMB equation was used to couple the improved PMG absolute permeability model with the CPL relative permeability model under the same reservoir pressure and water saturation. The dynamic prediction model of effective permeability of under-saturated coal reservoirs invaded and analyzed the dynamic change law of effective permeability of gas and water.The results show that the model unifies the effective permeability as a function of reservoir pressure, Negative effects, especially matrix shrinkage, have an effect on improving the effective permeability of gas phase. Water intrusion causes a decrease in net production water, resulting in a slowing down of water saturation, inhibiting the increase of effective gas permeability and the decrease of effective permeability of water phase. However, The influence on the shape of the curve is weak; if the water influx does not change any more, the constant speed water intrusion transforms into the quantitative water intrusion. Appropriately increasing the drainage speed helps to reduce the impact of water intrusion.