A Study on Coupling Relationship Between Artificial and Natural Fractures

Abstract

The coupling relationship between natural and artificial fracture was analysed by structural physical simulation experiments. Based on the similarity principle, to build the model by a certain percentage, natural fractures were designed in artificial ways. Change angle between direction of natural fracture extension and rock stress, several models were builded respectively. Then horizontal stress were applied on the models, through observing different angle between current geo-stress and natural fractures directions, and the change regularities of the starting position, extension direction and distribution of the artificial fractures can be got. The results show that, when the angle is less than 15°, artificial fractures extend mainly along natural fracture. When the angle is 30°, artificial fracture is perpendicular to the natural one, and extends along the natural one. When the angle is 45°, artificial fracture is firstly formed and perpendicular to the direction of natural fracture then extends along natural crack or current maximum pressure in the direction of the main stress. When the angle is greater than 45°, artificial fracture extends along the direction of the present maximum compressive stress. If natural fracture is encountered, the artificial fracture propagation terminated. Only to increase the stress intensity, it can pass through the natural fracture. This article research the relationship between artificial fracture and natural fracture, and the research result can effectively guide the fracturing design and the development well pattern.KeywordsNatural fractureArtificial fracturePhysical simulationStressFracturing