This paper focusses on the use of Newton Raphson iteration in determining gas compressibility factor (z) while performing tubing system performance for dry gas wells through the development of a computer model (TBG_SPARK). However, tubing performance analysis performed on the case study (Well-A and Well-B) revealed that the production system of Well-B performed better – since its tubing size and wellhead pressure was lower than that of Well-A. Also, investigations made using modified data revealed that, lower tubing sizes and higher wellhead pressures yield higher gas rates. Conversely, reverse was the case when wellhead pressures were not varied.