水平井体积压裂套管失效机制研究现状及趋势初探

Research status and development trend of mechanisms of casing failure caused by volume fracturing in horizontal wells

体积压裂过程中套管变形失效成为影响低渗透油田高效开发的难题。通过对体积压裂区实现全局嵌入Cohesive单元和渗流节点,并在体积压裂区预制天然裂缝,运用应力-渗流耦合的方法,完成体积压裂过程中套管两侧复杂裂缝网络非均匀扩展过程的刻画并进行仿真初探。初探结果表明,裂缝的非均匀扩展改变了套管内壁应力周期性变化的规律,使套管的最大应力区域发生偏移,破坏了套管的内壁应力周期对称性分布。综述其研究进展和发展趋势,总结出可通过刻画出的复杂裂缝网络群体非均匀扩展过程对水平井套管的影响规律,从体积压裂下非均匀载荷对套管强度影响这一视角修正水平井大规模体积压裂用套管强度设计方法,为保障压裂工况下套管使用寿命提供理论支持。

Casing failure during volume fracturing in horizontal wells has become an important issue affecting the effective development of low-permeability oil reservoirs.By embedding Cohesive units and seepage nodes globally in the volume fracturing zone,and prefabricating natural fractures in the volume fracturing zone,using the stress-seepage coupling method,finished the non-uniform propagation process of complex fracture network on both sides of casing during volume fracturing describing and simulating.The preliminary results show that the non-uniform expansion of cracks changes the regularity of the periodic changes of the inner wall stress of the casing,shifts the maximum stress area of the casing,and destroys the periodic symmetry distribution of the inner wall stress of the casing.Reviews its research progress and development trend,summarizes portrays the complex fracture network group by non-uniform extension process on the influence law of horizontal well casing,from volume fracturing under influence of non-uniform loading on casing strength in this angle correction mass volume of horizontal wells fracturing with casing strength design method,to ensure the service life of the fracturing conditions casing to provide theoretical support.