Experimental and numerical study on fracture propagation near open-hole horizontal well under hydraulic pressure

Using a true triaxial compression test apparatus, physical model tests are carried out to investigate the fracture propagation in open-hole horizontal wells under hydraulic pressure. The test results indicate that hydraulic fracture propagation is closely related to the direction of the minimum principal stress. When the difference between the maximum and minimum horizontal stresses is maintained at 10.0MPa and the angle between the horizontal well and the minimum horizontal stress varies from 0 degrees to 90 degrees, the fracturing pattern changes from transversal to longitudinal fractures. To capture the complex hydraulic fractures in heterogeneous rock materials, a three-dimensional numerical code incorporating the seepage-stress-damage coupled model is then employed to study the hydraulic fracture propagation near open-hole horizontal wells. The fracture propagation in horizontal wells under hydraulic fracturing is simulated and the numerical results are in good agreement with the experimental results. The stress distribution, failure-induced stress redistribution and the energy distribution, which are impossible to be observed in field and are difficult to be considered with static stress analysis approaches, are illustrated and discussed in detail based on numerical results. The experimental and numerical results in this study are expected to provide a meaningful guidance for oil production by hydraulic fracturing in horizontal wells.