确定致密气藏压裂井动态导流能力新方法

Determination of dynamic conductivity for fractured well in tight gas reservoir

致密气藏压裂井生产过程中,随着时间及有效应力的变化,裂缝导流能力会不断下降,呈现出动态导流能力特征。传统研究主要局限于室内实验,实验条件过于理想化,忽略了高速非达西流影响,而且只能分别确定裂缝导流能力的时效性和应力敏感性,无法确定两者对裂缝导流的共同影响。针对以上问题,文中运用分段历史拟合方法,采用数值模拟与压力恢复试井相结合的手段,提出了一套确定裂缝动态导流能力的方法,并分析了苏里格气田气井导流能力变化规律。结果表明,气井井底流压的压降速率越快,导流能力损失速度越大。因此,在压裂井生产过程中,要注意控制压降速率,以延长裂缝寿命。该方法对掌握压裂井裂缝导流能力变化特征、制定合理工作制度具有重要指导意义。

For fractured well in tight gas reservoir, the fracture conductivity will change with time and effective stress, which is called dynamic conductivity phenomenon. Traditionally, this phenomenon is mainly investigated by laboratory experiments, which is always idealistic and ignores high-velocity non-Darcy flow. In addition, laboratory experiments can only determine the timesensitivity and stress-sensitivity of conductivity respectively, but cannot reveal their combining effects on conductivity. Multi-stage history match method is used to solve these problems. By combining numerical simulation and well test interpretation, a new method is proposed to determine dynamic conductivity and to analyze wells in Sulige Gas Field. The results show that conductivity loss increases with the increasing of pressure drop speed. Therefore, pressure drop should be controlled to prolong the life of fracture. This method can contribute to dynamic conductivity as well as development.