This particular application of the ODSI Well Analyzer employed a direct numerical integration to the Mechanical Energy Balance equation for real-time surveillance of a subsea gas condensate well in the North Sea. Well Analyzer validated the metered gas rate, calculated bottom hole pressure (BHP) at mid-perforation depth, and evaluated the well as a potential candidate for stimulation. The study found that all downhole pressure gauges (DHPGs) had failed, and the analysis was based on historical data. The results demonstrated less than 1% error between measured and calculated gas rates and less than 2 psi error in BHP calculations, using wellhead pressure (WHP) and the calculated gas rate. It also highlights ODSI’s solution for accounting for phase-thermal changes in the wellbore. Ultimately, ODSI found that the well was not a stimulation candidate, emphasizing the importance of valid mid-perf BHP in pressure transient analysis (PTA) to avoid misinterpretation of well conditions, such as overestimation of permeability and skin, or underestimation of reservoir pressure.