油层套管射孔开裂的断裂力学模型

A Fracture Mechanics Model for Perforation Cracking of Oil Layer Casing

对油层套管在射孔作业时的受力状态进行了分析,用简化的断裂力学模型来描述复杂的射孔开裂问题,即:射孔开裂是由于射孔局部冲击力产生的孔眼尺寸的穿透裂纹在内压力产生的应力作用下沿轴向产生脆性扩展。可以通过测量射孔后管壁的横向流变应力和孔眼的实际最大尺寸来计算套管在射孔过程中不开裂的断裂韧性指标K_(Ic)。理论分析表明,应力强度因子作为射孔开裂判据,具有明确的物理意义和严密的理论依据,更能揭示射孔开裂的物理本质。

The load applied on oil layer casing during the perforation operation has been analyzed. The complex mechanism of perforation cracking can be simplified as a fracture mechanics model: the local impact force of perforation caused through - out tube wall cracks, i.e., holes, these cracks may brittle growth along the axial direction on the rule of stress. The fracture toughness Klc will be calculated by the transverse flow stress of tube wall and the actual maximum diameter of the aperture. Analysis results show that the fracture toughness can be used as criteria of perforation performance.