层状介质中水力裂缝的垂向扩展

VERTICAL GROWTH OF HYDRAULIC FRACTURE IN LAYERED FORMATIONS

应用岩石力学的理论与方法，建立了层状介质中水力裂缝垂向扩展的数值模型，分析了地应力剖面、地层断裂韧性、压裂液密度及作业参数对缝高剖面形态的影响．研究结果表明，地应力剖面是影响裂缝垂向扩展范围和扩展方向的主要因素，岩层断裂韧性对裂缝的垂向扩展有明显的止裂作用，压裂液沿缝高方向的流动压降对裂缝高度有较大影响．在一定地层条件下，裂缝是否向隔层扩展以及扩展范围的大小主要取决于作业压力的高低．

On the basis of rock mechanics theory, a numerical model is developed to simulate fracture vertical growth through layered formations. The parameters are studied with the model in order to evaluate the effects of in situ stress profile, rock fracture toughness, density of fracturing fluid and fracturing pressure on fracture height growth. It is demonstrated that the in situ stress profile is the most important factor affecting the fracture vertical growth dimenssion and direction. Rock fracture toughness has a distinct effect of containment on the fracture vertical growth, and the fracture fluid pressure drop in vertical direction has certain influences on fracture height. It is also shown that the fracturing operation pressure can be used to determine whether and how far the hydraulic fracture grows through upper and lower barriers under certain formation conditions. The model is useful to predict and monitor the fracture vertical extension and its geometry during field operations.