Study On The Fracture Initiation And Propagation Model For Shaly Loose Sandstone

This study exploring the role played by the different clay content in unconsolidated sandstone rock formations, and thinks that exceed certain levels of shale have an important impact to rock strength, above a certain percentage of clay component in loose sandstone played a role in the body of the natural structure of micro-cracks and weak cemented surface, combined with their high porosity unconsolidated sandstone features, making the rock mass strength weakened further,and shearing fracture is more complicated.To further study,through the shaly loose sandstone hydraulic fracturing analyze physical phenomena described experiments to investigate the cracks in the crack propagation characteristics and the impact of the expansion of its main features that occur during a variety of complex fractures. Analysis that appears of natural micro-cracks and muddy weak structural plane played a role of interference in the crack propagation.This article based on the physical experimental results of rock samples, using the discrete element software UDEC to simulate the crack phenomenon, pre-slit interference by network to inversion crack propagation conditions. And the foundation, through the mutual comparison of physical model and numerical model, the force field characteristics, pumping pressure parameters described in further analysis. The findings appear under tension and shear plastic zones are the main features caused by loose sandstone crack propagation. The results through research and analysis the models of shaly loose sandstone reservoir under different conditions from the hydraulic fracture crack extension, and make an explained to microscopic features. This research provides the basis for optimization shaly loose sandstone reservoir of hydraulic fracturing design, thereby improving the fracturing stimulation effect.