In unconventional reservoirs, the well life cycle includes drilling, completion, flowback, and production. The analysis of the fracturing pressure, flowback, and production data provides an early estimate of the stimulated rock volume (SRV) and reservoir flow capacity. In this paper, we present a methodology for using the average treatment pressure and hourly flowback data to characterize reservoir connectivity as an early indicator for long-term productivity. We will also show that performing flow regime analysis during the flowback period provides a greater understanding of the initial fracture conductivity (via bilinear flow) and reservoir connectivity (via linear flow). This early time analysis also sheds light on sweet spots (or geologically favorable areas) and effectiveness of the completion practices for business decisions. In this paper, we have modified the well-known single-phase diffusivity equation to include simultaneous flow of oil, water, and gas in the reservoir. Furthermore, we used fracture treatment pressure, flowback and production data from several Eagle Ford and Bakken wells to demonstrate the value of completion and flowback data and their relation to the long-term performance of wells.