Since their inception in late 90's, the phase-field models of fracture simulation have steadily gained popularity. One of the appeals is its ability to handle complex topologies with unknown crack paths in relatively coarse meshes as well as multiple-crack interaction, which is a fundamental requirement for the numerical simulation of hydraulic fracturing in complex situations and is technically more difficult to achieve with many other methods. In this talk, we will first describe the construction of a phase-field based coupled hydromechanical reservoir simulator. We will then revisit the problem of a single hydraulic fracture propagating in an infinite impermeable medium in order to validate the computation of fracture width and frac pressure from the phase-field model. Finally we will show how a phase-field description of a system of cracks can be leveraged to model flow in a fractured porous medium and describe the coupling of the flow and mechanics problems, and illustrate the properties of this model through various numerical simulations.