13th International Conference on Fracture June 16–21, 2013, Beijing, China -6- Direction of artificial fracture x y z Figure 4 Experimental image of 4# sample after hydraulic fracturing From the above experiments, we can conclude that the defect is one of the most important factors for the fracture morphology after re-fracturing in heterogeneous reservoir. However, whether the direction of the fracture propagation will be changed by the defect is finally directed by the stress distribution state in the reservoir, which meets the maximum tensile stress criterion. At the same time, we found that, under the higher uniform pressure stress, the direction of the new fracture may have no relation with the preset fracture in the defect reservoirs. Conclusion Theoretical research and indoor experiments have shown that the defect is one of the most important factors affecting the fracture distribution state after re-fracturing in the reservoir. From this paper, we can conclude as follows. (1) Theory research shows that, in a certain stress condition, a new fracture may produce along the tip of the inclusion. (2) The strength of the rock is dispersed for defects of various scales in the rock. (3) Whether the presence of defects will cause the new fracture, to a great extent, is controlled by the far field stress. (4) From the experiments, under some higher confining pressure, the defect may be the dominant factor of fracture propagation in the reservoirs. References [1] Beugelsdijk L J L, Pater C J, Sato K. Experimental hydraulic fracture propagation in a multi-fractured medium. SPE 59419, 2000. [2] Peacock D C P, Mann A. Controls on fracturing in carbonate rocks. SPE 92980, 2005. [3] Warpinski N R, Lorenz J C, Branagan P T, Myal F R and Gall B L. Examination of a cored hydraulic fracture in a deep gas well. SPE 22876, 1993.
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