应力敏感对致密气藏压裂水平井产量的影响

Influences of Stress Sensitivity on the Productivity of Fractured Horizontal Well in Tight Gas Reservoirs

为研究致密砂岩气藏储层应力敏感现象对不同井控面积下压裂水平井产量的影响,利用数值模拟软件建立单井机理模型,引入孔隙压缩系数以及孔渗幂指数分别研究在不同井控面积情况下孔隙体积变化以及孔隙裂缝特征对压裂水平井产量的影响。研究结果表明:孔渗幂指数越大,在相同的孔隙压缩系数的前提下渗透率应力敏感性越强,对产量影响越大。对于井控面积大的压裂水平井,裂缝系统渗透率为影响产量主要因素,孔隙压缩系数大导致裂缝导流能力下降快,影响产量;对井控面积小的压裂水平井,生产初期渗透率为影响产量主要因素,孔隙压缩系数大对产量影响大;生产后期,地层压力为影响产量主要因素,由于压实作用气井可保持较高的生产能力。

In order to precisely predict the productivity of fractured horizontal well in tight gas reservoir,the consideration of the strong stress-dependent permeability in the fracture system is very important.The different pore compressibility and porosity permeability power exponent were applied in the numerical model of multi-stage fractured horizontal single well,and the effects on the productivity of single well based on different well space were analyzed.The results indicate that with the porosity permeability power exponent increase,the stress sensitivity of permeability is increase and the impact on production is stronger.The daily production of larger area model is lower than basecase with higher pore compressibility.The permeability is the main factor influencing production.With the pore compressibility increase,the daily production of smaller area model is lower than basecase at the first half development stage and higher than basecase at the second half stage.Because of the reservoir pressure of small area model is widely spread,the well has maintained relatively high productivity due to the compaction effect,the formation pressure is the main factor influencing production at this production stage.