The optimal design of hydraulic fracturing parameters is the key to commercial exploitation of unconventional reservoirs. Hydraulic fracturing test is one of the main methods for optimizing fracturing parameters. It is known that scale effect exists between laboratory experiments and field treatments of hydraulic fracturing. However, studies on how to eliminate the scale effect are rarely reported. In this work, we conduct sensitivity analysis on rock mechanical parameters and fracturing parameters at different scales by using the dimensionless analysis method. The initiation and propagation process of field hydraulic fracturing is reproduced through laboratory tests, and fracturing parameters are analyzed by using numerical simulation. Our results show that the fracture propagation in the laboratory is inconsistent with that in the field fracturing. The fracture initiation and propagation in the field can be reproduced in experiments by using samples with high modulus and low toughness as well as high-viscosity fracturing fluid. Microcracks are created before the breakdown pressure is reached, and hydraulic fractures extend perpendicular to the direction of the minimum principal stress. The Carter’s leak-off coefficient has little effect on breakdown pressure and propagation pressure, but the injection rate and the horizontal principal stress have significant effects on breakdown pressure. This study provides a theoretical basis and guidance for the design of fracturing parameters both in the laboratory and in the field.

Because of the special geographical location adjacent to the Tibetan Plateau, the geological setting of the Sichuan Basin is very complex, which brings a great challenge to shale gas development. In this study, we conducted an integrated microseismic and geomechanical analysis on a refracturing well in the Sichuan Basin. We observed that casing deformation occurred in the area of fault reactivation. However, the reactivation of pre-existing faults does not always cause casing deformation. In addition, a cluster of high-magnitude microseismic events will be triggered during the fault reactivation, which is also helpful to recognize the reactivated faults. Furthermore, according to the definition of b-value in the Gutenberg–Richter law, a group of high-magnitude microseismic events usually shows a low b-value and vice versa. Based on the analysis of treatment data and microseismicity, we found that there is a positive relationship between b-value and instantaneous shut-in pressure (ISIP): lower b-value represents lower ISIP. The investigation of the stress shadow effect based on the theoretical solution of a plane strain fracture is also convincing to prove the relationship between b-value and ISIP. Therefore, a significant relationship between hydraulic fracturing, microseismicity, and fault reactivation is established. Importantly, some useful implications of this relationship could be utilized for early warning of fault reactivation (probably casing deformation) and optimization of refracturing design for unconventional shale plays.