Fluid pressurisation at depth can reactivate pre-existing fractures and faults by triggering frictional slip that ranges from slow (aseismic) slip to dynamic rupture. These can occur in response to either anthropogenic fluid injection (e.g. hydraulic stimulation) or via natural occurrences (e.g. serpentine dehydration). Hydraulic stimulation, widely used in geo-energy applications, enhances rock permeability by reactivating fractures using pressurized fluid injection. Recent studies have made significant strides in quantifying the mechanics of fluid-induced frictional slip in single-plane systems. For instance, Sáez and Lecampion (2024) identified four distinct slip regimes for a fluid-induced slip-weakening fault in 3D, progressing from quasi-static slip to nucleation, arrest, and ultimately a runaway dynamic rupture based on three dimensionless numbers linking in-situ stress state, injection strength and peak and residual friction coefficients. However, the response of interconnected fracture networks, which is more representative of real-world subsurface conditions, to fluid injection, remains poorly understood. Although some numerical studies (e.g. Ciardo & Lecampion (2023)) have qualitatively explored the behavior of fracture networks subjected to fluid injection, detailed quantification of energy distribution and slip mechanics within these interconnected systems have not been investigated in detail. In this study, we present a comprehensive energy balance for a hydro-mechanical system comprising an elastic host rock, an interconnected poroelastic fracture network, and injected fluid. Our primary goal is to understand the overall energy budget, and notably quantify the partitioning of the energy dissipated in plastic slip along major and the surrounding minor fractures. The derived energy balance is validated using a hydro-mechanical numerical solver. Simulation results reveal that fluid viscous dissipation accounts for the dominant share of the injected energy, followed by dissipation due to plastic slip. Leveraging this energy balance, we examine whether the presence of smaller surrounding fractures around a main fault leads to a shielding effect that limits rupture propagation, or a promoting effect that facilitates rupture growth and enhances energy transfer.