Assessing the effect of gas temperature on gas well performance

Gas temperature is an essential parameter in estimating production rate and pressure model inside the production tubing. Three heat transfer mechanisms named as conduction, convection and radiation have been applied to identify the gas temperature declination. Gas wells with bottom hole temperature greater than 160oC and gas rates reaching 55 million standard ft3 per day (MMscf/d) indicate a higher heat loss due to convection than the other two mechanisms. Conduction is the main factor in explaining heat diffusion to the surrounding at the top of the well. The study presents a strong similarity in value compared to the field data by combining Gray correlation and heat transfer model to predict the bottom hole pressure with an error of approximately 3%. Additionally, the gas temperature affects gas rate prediction through gas viscosity and Z factor. With the gas composition mostly containing C1 (70.5%), gas viscosity and Z coefficient at the wellhead are not as high as 0.017 cp and 0.92 respectively. It is possible to have a two-phase flow, then a temperature model along the production tubing is necessary to ensure the gas production rate.