Prediction of Casing Pressure for High-productivity Gas Wells with Sulfur

In production period,high-temperature formation fluid can raise wellbore temperature,further lead to an increase of casing pressure and an enlargement of tubing expansion effect. According to an analysis on the reason why annulus pressure of high-productivity gas wells changes during production,considering the effects of wellbore temperature variation,liquid volume change of enclosed space,and tubing expansion effect on casing pressure, we developed a model to predict coupling operation of casing pressure increment. It provides a theoretic basis for selecting completion-fluid density,optimizing downhole-tool parameter,assessing wellbore safety,and optimizing production system.