复杂应力环境下纤维水泥阻裂机理实验研究  

Crack resistance mechanism of fiber cement under the action of complex stress

作　　者：步玉环[1] 穆海朋[1] 王瑞和[1] 沈忠厚[1] 

机构地区：[1]中国石油大学石油工程学院,山东东营257061

出　　处：《石油学报》2008年第6期922-926,共5页Acta Petrolei Sinica

基　　金：国家高技术研究发展计划(863)项目(2006AA09Z340)资助

摘　　要：水泥环在井下复杂应力环境下易发生脆裂而引起"二次窜流"。在水泥中加入纤维可以改善水泥环的韧性。利用电镜扫描的手段对纤维水泥石受拉、受压以及受射孔冲击破坏产生的裂纹进行的镜像分析实验表明:纤维的存在会使水泥石微裂纹处局部强度增加,从而增加了水泥石抗压强度。同时,纤维的加入使得水泥石的断裂应力强度因子降低,从而增强了水泥石的抗断裂能力。不论裂纹发展方向与纤维长度方向垂直还是一致,纤维—基体界面对裂纹的发展都有一定的阻挠作用。在纤维水泥石受压、受拉以及射孔的破坏过程中,纤维对裂纹的发展都起到了阻裂作用。这种阻裂作用增加了水泥石的韧性,一方面有助于射孔完井作业的顺利完成;另一方面有助于水泥承受复杂的井下应力,进而减少"二次窜流"现象的发生。根据纤维水泥阻裂的机理,建立了纤维水泥阻裂的力学模型。The surface of cement sheath in well bore is easy to be fractured. The fiber was used to improve the toughness of cement. When suffered from stretching, compression and perforation, the cement surface produced some cracks. Based on scanning electronic microscope, the analysis on fractured surface of fiber cement indicates that the intension of micro crack in cement can partly be increased because the existence of fiber leads to the enhancement of compressive strength of cement. The stress intensity factor of cement can also be reduced because the existence of fiber can improve the ability of resistance to rupture of cement and make the toughness of cement strengthen. The fiber-matrix interface can prevent the crack from propagating in cement whether the propagation trend of crack is vertical or congruent to the stretch direction of fiber. Fiber can prevent the fracture from seriously extending during the fiber cement being exerted compression, stretching and perforation. Thus the toughness of cement can be strengthened, which is helpful to ensure the success of perforating completion operations. Based on the analysis of experiments phenomena, the crack resistance mechanism of fiber cement was analyzed and its mechanical model was built up.

关 键 词：水泥环 纤维水泥 阻裂作用 镜像分析 微裂纹 力学模型 实验研究 

分 类 号：TE256.7[石油与天然气工程—油气井工程]