The explanation of low recovery of fracturing fluid in shale hydraulic fracturing by pore-scale simulation
The explanation of low recovery of fracturing fluid in shale hydraulic fracturing by pore-scale simulation
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DOI：
10.1360/n972014-00461
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发表时间：
2014-11
影响因子：
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通讯作者：
Z. Lei;Kang QinJun;Yao Jun;G. Ying;S. Hai
中科院分区：
文献类型：
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作者：
Z. Lei;Kang QinJun;Yao Jun;G. Ying;S. Hai
针对页岩水力压裂压裂液采收率低的特点，在孔隙尺度上模拟了水与气之间的驱替过程。模型采用高密度比格子Boltzmann模型，几何形状为三维页岩数字岩心，以高分辨率扫描电子显微镜图像为输入，用马尔科夫链蒙特卡罗方法重建。通过计算表面张力和相对渗透率对模型进行了验证。水(气)先饱和，然后在入口处注入气(水)。当出口处发生位移相突破时，模拟终止。气体和水的动粘比和密度比分别设定为10：1和1：1000。水驱气突破时含水饱和度为70%，气体推进相突破时含气饱和度仅为4.5%。在三维数字岩心中给出了位移相位的分布。当水被气体驱替时，大多数水被困在孔隙中。从而解释了压裂液在页岩中采收率低于10%的现象。
Within the low recovery of fracturing fluid during hydraulic fracturing in shale, the displacement between water and gas is simulated in pore-scale. The lattice Boltzmann model with high-density ratio is employed, and the geometry is three-dimensional shale digital core, which is reconstructed by Markov Chain Monte Carlo method with a high resolution SEM scanning image as input. The model is verified by calculating the surface tension and relative permeability. Water (gas) is saturated at first, and then, gas (water) is injected at inlet. The simulation is terminated when breakthrough of displacement phase occurs at outlet. The kinetic viscosity ratio and density ratio of gas and water are set to 10:1 and 1:1000, respectively. The water saturation is 70% at breakthrough when water displaces gas, while the gas saturation is only 4.5% at breakthrough when gas is advancing phase. The distribution of displacement phase is given in three-dimensional digital core. Most water is trapped in the pore at breakthrough, when water is displaced by gas. Hence, the phenomenon of recovery of fracturing fluid is less than 10% in shale is explained.