缝洞型碳酸盐岩近井筒裂缝转向模拟研究

缝洞型碳酸盐岩油气储层在非主应力方向上存在许多储集体，水力压裂开采技术产生的压裂缝传统的扩展模式为对称双翼扩展线性裂缝，此方式很难沟通大量存在于非最大主应力方向上的储集体。定向射孔并控制水力裂缝扩展路径是解决此问题的关键。本文通过定向射孔压裂起裂模型判断水力裂缝起裂，最大周向应力准则作为判断裂缝转向扩展的依据，结合顺北某油气田实测参数，利用Abaqus扩展有限元法对射孔方位角、水平地应力差、射孔深度、压裂液排量等影响水力裂缝近井筒转向扩展的因素进行数值模拟。结果表明：射孔方位角、水平地应力差是水力裂缝转向扩展的主要控制因素；射孔深度的影响受水平地应力差的控制；压裂液排量的大小对于水力裂缝转向扩展几乎没有影响。

Simulation Study on Crack steering of Near-wellbore in Crack-hole Type Carbonate Rock

There are many reservoirs in the non-principal stress direction of crack-hole type carbonate rock reservoirs.The traditional hydraulic fracturing cracks are symmetric double-wing extended linear cracks, which is difficult for the reservoirs in the direction of non-maximal principal stress. Directional perforation and control of the hydraulic fracture propagation path are key to solving this problem. In this paper, the hydraulic fracture initiation is judged by the directional perforation fracturing and cracking model. The maximum circumferential stress criterion as a criterion for judging the turning of cracks. Combined with the measured parameters of a certain oil and gas field in the north of Shun Bei. The orientation angle, difference of horizontal geostress , perforation depth and displacement of fracturing fluid are used by Abaqus extended finite element method(XFEM). The fracturing fluid displacement and other factors affecting the hydraulic crack steering of near-wellbore expansion are numerically simulated. The results show that the orientation angle and difference of horizontal geostress are the main controlling factors for the hydraulic crack propagation. The effect of the perforation depth is controlled by the difference of horizontal geostress. The level of fracturing fluid displacement has little effect on the hydraulic fracture steering expansion.