Experimental study on re-fracturing in defective reservoirs

The distributions of fractures after re-fracturing in defective reservoirs are studied by using a series of large size true tri-axial test systems for the first time. The experimental results show that the stress redirection has a great impact on the distribution of new cracks. When the load reaches a certain critical value, defects will be activated during hydraulic fracturing, and more complex fractures will be formed. Whether new fractures propagate along the preset fracture or not largely depends on the stress state, geological conditions, and so on. Especially under the higher uniform stress, the direction of new fractures has nothing to do with the preset ones.