A new three dimensional approach to numerically model hydraulic fracturing process

In this paper, a Three-dimensional Distinct Element Code (3DEC) was used and developed for simulating the initiation and propagation of hydraulically induced fractures in a typical reservoir hosted by a rock mass. Due to the fact that the modeling of the initiation of fracturing through intact rock within the Discrete Element Method (DEM) is not possible, a fictitious joint technique was introduced in order to simulate the process. The analysis results substantiate the previous understanding that the success of the hydraulic fracturing process not only depends on controllable parameters such as fracture fluid properties and injection rate, but also relies on the uncontrollable parameters such as ground in-situ stress regime, orientation of principal stresses, and in-situ rock mass properties. Moreover, a sensitivity study of input variables was carried out to examine the effect of different field conditions which involved the orientation and magnitude of principal stress components, fracture fluid properties, injection rate and rock parameters. Comparing the results with analytical solution indicated that the model provides a reasonable approximation for computing fluid injection pressure. Thus, the proposed modeling procedure can be employed in more complicated cases for further studies, such as interaction between induced hydraulic fractures and natural fractures.