非均匀孔隙压力场导向水压裂纹扩展机制

为揭示非均匀孔隙压力场对水压裂纹扩展的影响,采用多孔弹性力学、断裂力学、渗流力学和热弹性力学理论,建立了考虑孔隙压力的水压裂纹尖端应力强度因子计算模型,并采用室内实验和RFPA2DFlow数值模拟软件进一步分析了非均匀孔隙压力场对水压裂缝扩展的导向机制.研究结果表明:孔隙压力场的存在可以增大水压裂纹尖端的应力强度因子,从而诱导水压裂缝沿高孔隙压力方向扩展;同时,水压裂纹尖端的应力强度因子会随着孔隙压力增大而增大,孔隙压力越大,裂纹的偏转幅度也会越大.

Mechanism of Hydrofracture Propagation Control by Non-uniform Pore Pressure Field

To reveal the effect of non-uniform pressure on hydraulic fractures propagation， the porous elasticity mechanics， fracture mechanics， seepage mechanics and thermal elasticity mechanics were used to build a hydrofracture crack tip stress intensity factor calculation model considering the pore pressure. Then， through laboratory experiments and numerical simulation， the guiding mechanism of pore pressure on hydrofracture was verified. The research results showed that pore pressure can increase the crack tip stress intensity factor of hydrofracture， which causes the fractures extend to the high pore pressure region; at the same time， stress intensity factor of hydrofracture will be enlarged with the increase of pore pressure. A larger pore pressure will lead to larger deflection amplitude of fractures.