Real-Time Estimation and Management of Hydrate Plugging Risk During Deep-Water Gas Well Testing

Abstract

Hydrate formation and deposition usually exist during deep-water gas well testing, which easily cause plugging accident in the testing tubing if it was not found and handled in time. A method to estimate and manage hydrate plugging risk in real-time during deep-water gas well testing is developed in this work. This method mainly includes the following steps: predicting hydrate stability region, calculating hydrate behaviors, analyzing the effect of hydrate behaviors on the variation of wellhead pressure, monitoring the variation of wellhead pressure and estimating hydrate plugging risk in real-time, and managing hydrate plugging risk in real-time. As hydrates continue to form and deposit, the effective inner diameter of the tubing decreases, and the wellhead pressure also decreases accordingly. The risk of hydrate plugging can be estimated by monitoring the variation of wellhead pressure. When the wellhead pressure decreases to the critical value for safety at a given gas production rate, it is indicated that hydrate plugging is likely to occur. Under this condition, hydrate inhibitor is needed to inject into the tubing to reduce the severity of hydrate plugging, and real-time monitoring of wellhead pressure variation is also needed to guarantee the risk of hydrate plugging in the testing tube is within safe range. By using this method, the real-time estimation and management of hydrate plugging during the testing process can be achieved, which can provide basis for the safe and efficient testing of deep-water gas wells.